MECHANICALCOMPONENTSAND MAINTENANCEfor malaysian polytechnic handbook

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Preface

MECHANICALCOMPONENTSAND MAINTENANCEcoversbasicmechanical

componentsneedsinIndustry.Thetopicincludesmaintenanceprinciples,procedures,

lubrication,powertransmission,bearing,clutches and brakes and pumps,valves and

compressor.Thiscoursealsogivesknowledgeandskillsregardingmaintenanceof mechanical

componentsand assemblies.

EditorArman Bin Md Said

Table of Contents

1.0 MAINTENANCEPRINCIPLESANDPROCEDURES1.1 Understandingof maintenance.

1.1.1 Definethemeaningofmaintenance.1.1.2 Describe theobjectiveandadvantagesofimplement

maintenance. 1.2 Explain various types of cost maintenance related.

1.3 Describeworkplacesafety.1.3.1 Identifythebenefitcleanandsafeworkingenvironment.1.3.2 Explaintheimportantof personal protectionequipments.1.3.3 Uselockoutandtag-outwhenneeded.1.3.4 Identifyalltheorganizationthatgovernsthesafetyof

hazardousmaterial.

1.4 Identifytypesofhand tools,powertoolsandmaintenanceequipments.1.4.1 Listthe mostcommon typesofhand tool andpowertools.1.4.2 Demonstratetheproperuseofvarious typesofhandtooland powertools.1.4.3 Determine theimportanceofinspectingahand toolandpower

tools

2.0 LUBRICATION

2.1 Understandlubrication principle.2.1.1 Describelubricationsystemandbenefitimplement

lubricationsystem.

2.1.2 Stateseveralterm andprincipletounderstandandselect properlubrication.

2.2 Understandfluidmanagement.2.2.1 Applyfouressentialcomponentsina fluid management

program.a. Selectionandpurchaseoflubricationb. Lubricationmonitoringduringusec. Lubricantmaintenanceusingprocessing d.

Refortificationtechniquese. Disposalofthespentlubricant.

2.3 Identifylubricatingdevicesandsystem.2.4.1 Evaluateeffectivenesslubricatesuchasselectrightlubricant

type,place, amountandtimeto use.2.4.2 Choosesuitable lubricatingdevices systembased onequipment

ormechanical components.

3.0 POWERTRANSMISSION

3.1 Describethedrivemechanismintheprocessoftransformingpower fromone pointtotheother.3.1.1 Classifytypesof drivemechanismsbeltdrive, chaindrive and gear

drive

3.2 Describegear in powertransmissionsystem.3.2.1 Listapplicationofgear.3.2.2 Classifytypes ofgearsandtheir characteristics basedonit’s

function.3.2.3 Identify gearmeshingandbacklash.3.2.4 Explain coupling concept into gear system.3.2.5 Identifygearmaintenancepracticesuchasdailyroutine

inspection.3.2.6 Developgearchecklistforpreventivemaintenance,symptoms

andrecord observationforpreventive maintenance ,etc.3.2.7 Assembleanddisassembleafewtypesofgearsa practical.As an examples

componentscanbeuseisassemblyspurgearexercise or assemblyspur wheel /wormgear station.

3.2.8 Developmaintenanceprocedure.a. Geartooth-wearandfailure.b. Lubrication contaminationandincorrectlubrication. c. Overheating.d. Lowoillevel,etc

3.3 Definebeltdrives inpower transmissionsystem.3.3.1 Listapplicationofbeltdrives.3.3.2 Classify FIVE typesofbelt drivesandtheircharacteristicsbasedonit’sfunction.3.3.3 Identifybelttensionand misalignmentofbeltdrives.3.3.4 Developedchecklistdrives belt maintenance, symptoms and

recordobservationsforpreventive maintenance.a. Prematurebeltfailure.b. Severeorabnormalbeltwear. c.

Banded(joined)beltproblems.d. Beltnoiseandunusualvibration.e. Problemswithsheaves,beltstretchesbeyondtakeup. f. V-beltturnoverorjumpoffsheave,etc

3.3.5 Producebeltdrivemaintenanceprocedure.

3.4 Understandchain drive.3.4.1 List applicationof chaindrive.3.4.2 Classify FIVEtypesofchaindrive and theircharacteristicsbasedonit’sfunction.3.4.3 Developchecklistchaindrivemaintenance,symptomsand

recordobservationforpreventive maintenance.3.4.4 Producechaindrivemaintenanceprocedure.

3.5 Implementcoupledshaftalignment orvariable-speed drives.

3.5.1 Describethefundamentalsofshaftalignment.3.5.2 Demonstratetheuseof thereversedialindicatormethodsto correct

shaft misalignment.3.5.3 Assembleanddisassembleofmechanicaldrivesystemasa

practical.Asanexamples components canbeusearegear assemblyforcombined drivesandalignment of drives, shaftsandgear.

4.0 BEARING

4.1 Understandbearingconcepts.4.1.1 Listapplicationof bearing.

4.1.2 Classify FIVE types of bearing based on its application.4.1.3 Identify bearing numenclature and code base on ISO

4.1.4 Explain Bearing Service Life, in hour or rotation

4.1.5 Explain the concept ofseals,gasketsandpackingintobearing system.

4.2 Understandfriction, temperature andlubrication.4.2.1 Identifyfrictioninbearingsystem.4.2.2 Relateoperatingtemperaturewithbearingfriction.4.2.3 Identify principleofbearinglubrication.

4.3 Describe mountinganddismountingofbearing.4.3.1 Applymountinganddismountingequipment andtools.4.3.2 Usemeasuringequipmentforbearinginstallation.4.3.3 Applyconcepttoadjusting theclearanceduringinstallation.4.3.4 Classifymountingmethods likes cold mounting,temperature

mounting,mounting tapered-borebearing,dismountingofbearing,hydraulic method.

4.3.5 Assembleanddissembleofbearingasapractical.As anexamples componentscanbeuseare assemblyshaftwith journal bearingsandassemblyhydrodynamic journal bearing.

4.4 Understandbearingdamage.4.4.1 Developedbearing maintenance check list,symptoms forpreventive maintenance.

a. Fatigue,vibrationandwearb. Corrosiondamage.c. Scuffingandslidingmarks.d. Localindentationsintheraceway.e. Faultymountinganddefectiveinstallationmethods.f. Poorlubricationand faultindesign.

5.0 CLUTCHES ANDBRAKES

5.1 Describe clutchesandbrakesprinciple.5.1.1 Identifyfunctionofa clutch and brakes.5.1.2 Classify various typesof clutches based on:i- Mechanicalii- Electric andiii- Hydraulic5.1.3 Assembleanddissembleclutch and brake as a practical

.Componen t s canbeuseare multiple plate clutch and drum brakes

5.2 Develop clutchesand brakes maintenance procedure5.2.1 Developedchecklist clutchesand brakesmaintenance

,symptomsandrecordobservationsforpreventive maintenance.

6.0 PUMPS,VALVESANDCOMPRESSOR

6.1 Understandpumpsconcepts.6.1.1 Listapplicationofpumps.6.1.2 Classifytypes ofpumpsbasedonit’s

principle.i. Positive displacementii. Rotor dynamic

6.1.3 Assembleanddisassemblepumpasapractical.Asaexamples componentscanbeuseiscentrifugal pump.

6.1.4 Developedcheck list pumpsmaintenance,symptomsandrecord observationsforpreventive maintenance.

6.2 Understand valve concepts.6.2.1 Listapplicationofvalve.6.2.2 Classify FOURtypes of valveandtheir characteristics basedonit’s

function.i. Butterflyii. Gateiii. Balliv. Globe

6.2.3 Assembleanddisassemblea fewtypesofvalveasapractical.Asanexamplesapparatuscanbeuseareassemblygate valve andangleseat valve,assemblybutterflyvalve and non-return valve,assemblyball valve andglobe valve.

6.2.4 Developedchecklistvalvemaintenance,symptomsand recordobservationsforpreventive maintenance.

6.3 Understandcompressor concepts.6.3.1 Listapplicationofcompressor.6.3.2 Classifytypesofcompressor based on it’sfunction.

i. Positive displacement

iii. Rotor dynamic

6.3.3 Identifyprinciple andcharacteristicofcompressor.6.3.4 Determinecompressormaintenanceconcept.

Assembleanddisassembleafewtypesofacompressorasapractical.Asanexamplescomponentcanbeuse ispistoncompressor.

6.3.5 Developedchecklistcompressormaintenance,symptoms andrecordobservations forpreventivemaintenance.

2.4 Determinelubricatingprogram.a. Theplantlubricationsurvey.b. Establishmentoflubricationschedulesand improvementsin

selection and applicationoflubrication.c. Lubricationanalysis

INDEX

REFERENCES

1Hashimi Bin Lazim (PTSS)Zulkifli Bin Sulaiman (POLIMAS)

1.0 MAINTENANCEPRINCIPLESANDPROCEDURES

Introduction

Maintenance, repair, and operations (MRO) or maintenance , repair, and overhaul involve fixing any sort of mechanical, plumbing or electrical device should it become out of order or broken (known as repair, unscheduled or casualty maintenance). It also includes performing routine actions which keep the device in working order (known as scheduled maintenance) or prevents trouble from arising (preventive maintenance). MRO may be defined as, "All actions which have the objective of retaining or restoring an item in or to a state in which it can perform its required function. The actions include the combination of all technical and corresponding administrative, managerial, and supervision actions.

1.1 Understandingof maintenance.

1.1.1 Definethemeaningofmaintenance.

I. Based on language maintenance is activities required or undertaken to conserve as nearly, and as long, as possible the original condition of an asset or resource while compensating for normal wear and tear.

II. The definition of maintenance often stated maintenance as an activity carried out for any equipment to ensure its reliability to perform its functions.

MAINTENANCEPRINCIPLESANDPROCEDUR

Learning Outcomes

III. In engineering maintenance are actions necessary for retaining or restoring a piece of equipment, machine, or system to the specified operable condition to achieve its maximum useful life. It includes corrective maintenance and preventive maintenance.

IV. Maintenance is work that is carried out to preserve an asset (such as a roof or a heating boiler), in order to enable its continued use and function, above a minimum acceptable level of performance, over its design service life, without unforeseen renewal or major repair activities.

1.1.2 Types of Maintenance

I. Breakdown maintenance

It means that people waits until equipment fails and repair it. Such a thing could be used when the equipment failure does not significantly affect the operation or production or generate any significant loss other than repair cost

II. Preventive maintenance ( 1951 )

It is a daily maintenance (cleaning, inspection, oiling and re-tightening), design to retain the healthy condition of equipment and prevent failure through the prevention of deterioration, periodic inspection or equipment condition diagnosis, to measure deterioration. It is further divided into periodic maintenance and predictive maintenance. Just like human life is extended by preventive medicine, the equipment service life can be prolonged by doing preventive maintenance

a) Periodic maintenance (Time based maintenance - TBM)

Time based maintenance consists of periodically inspecting, servicing and cleaning equipment and replacing parts to prevent sudden failure and process problems.

b) Predictive maintenance

This is a method in which the service life of important part is predicted based on inspection or diagnosis, in order to use the parts to the limit of their service life. Compared to periodic maintenance, predictive maintenance is condition based maintenance. It manages trend values, by measuring and analyzing data about deterioration and employs a surveillance system, designed to monitor conditions through an on-line system.

III. Corrective maintenance ( 1957 )

It improves equipment and its components so that preventive maintenance can be carried out reliably. Equipment with design weakness must be redesigned to improve reliability or improving maintainability

IV. Maintenance prevention ( 1960 )

It indicates the design of a new equipment. Weakness of current machines are sufficiently studied ( on site information leading to failure prevention, easier maintenance and prevents of defects, safety and ease of manufacturing ) and are incorporated before commissioning a new equipment

1.1.3 Describe theobjectiveandadvantagesofimplement maintenance.

The purpose of maintenance is to attempt to maximize the performance of equipment by ensuring that such equipment performs regularly and efficiently, by attempting to prevent breakdowns or failures, and by minimizing the losses resulting from breakdowns or failures. In fact it is the objective of the maintenance function to maintain or increase the reliability of the operating system as a whole.

The maintenance function has not, during the past years, been seen as a condition for production. Instead the previous action approach was that the maintenance was the necessary evil which only consumed a lot of money. Very often the maintenance cost was seen too high.

This way of seeing maintenance was a sign of that the only objective of maintenance was to repair and mend broken equipment. This is the old fashioned way of maintenance management.

In modern maintenance management, it is not recommendable to concentrate 100% on breakdown jobs and repairing. Modern maintenance management is to keep the equipment into operation and produce quality products meaning that every time we need to do a unplanned repair work, we have not succeeded with the maintenance strategy.

In fact the objective of the maintenance activity is a priority one to work for a planned availability performance and priority two is to do this at the lowest cost possible. Obviously the safety aspects must also be taken into consideration.

The objective of maintenance in the industry is: - To achieve the correct level of operational reliability and best possible personal safety at minimum cost. Or in another words the objective of maintenance can be mentioned as follows: - To keep up the planned availability performance at the lowest cost and within the safety prescriptions.

Planned availability performance means that the production manager and maintenance manager have agreed on the availability performance for a certain period of time in the future.

It is essential to mention that the target of availability performance is decided first, secondly the cost factors are taken into consideration.

This objective can also be described as an attempt to achieve the optimum or best possible operational reliability i.e. the most economical operational reliability at as low a cost as possible.

In order to achieve this, a number of measures are employed, some of which are described below.

I. Planning of work improves the likehood of ensuring that the correct work is carried out at the right time. Planning also provides information for purchasing spare parts and materials and for determining personal requirements.

II. Various means of learning from experience can also be employed. One way is tokeeprecord every operational problem. This data can be used as a basis forplanning.

III. Maintenance can also be facilitated through design changes, improved lubricants, improved suspension system etc., all of which can reduce the need for maintenance.

IV. It is important to reduce maintenance requirements when maintenance work is to be rationalized.

V. Within the majority of areas, the amount of maintenance work necessary can bereduced through improved application of experience, improved planning andbetter design, coupled with application of suitable methods of investigating thecondition of plant and machinery (condition monitoring).

VI. Maintenance contributes to reduced consumption of capital by helping tomaintain the value of materials and equipment.

VII. Correct maintenance also extends the life of the equipment. This means that fund that would otherwise have been required to invest in (i.e. purchase) newequipment, can be used for other purposes within the company.

VIII. The way in which maintenance is carried out in a company is of considerable economic importance. Proper maintenance increases reliability and, therefore,productivity, resulting in increased revenue.

Most of the measures described above result in less time and material being required for maintenance, leading to reduced costs for the company. In general, it can be said that preventive maintenance increases the profitability of the company.

Properly carried out maintenance results not only in economic gains, but also in an improved working environment, improved human safety and reduced stress. Energy consumption and capital costs can also be reduced through proper maintenance.

1.1.3.1 Objective of Implement Maintenance

I. To achieve product quality and customer satisfaction through adjusted and serviced equipment

II. Maximize useful life of equipmentIII. Keep equipment safe and prevent safety hazardsIV. Minimize frequency and severity of interruptionsV. Maximize production capacity – through high utilization of facilityVI. Must be consistent with the goals of production (cost, quality, delivery, safety)VII. Must be comprehensive and include specific responsibilities

1.1.3.2 Advantages of Implementing Maintenance

I. Lower operating costsII. Faster, more dependable throughputIII. Higher productivityIV. Improved qualityV. Continuous improvementVI. Improved capacityVII. Reduced inventory

a. Advantages of Corrective Maintenance

I. Lower short-term costs.II. Requires less staff since less work is being done.

b. Advantages of Preventive Maintenance

I. Increased component lifecycle.II. Reduced asset failure.III. Some potential energy savings.IV. Estimated 12-18% cost savings over Corrective Maintenance (CM).

c. Advantages of Predictive Maintenance

I. Increased component lifecycle.II. Decrease in equipment downtime.III. Estimated 6% to 15% cost savings over Preventive Maintenance (PM) program

1.2 Explain various types of cost maintenance related.

1.2.1 Introduction

All enterprises and organisations are of course interested in lowering the maintenance costs. The maintenance cost must be controlled by the people with a knowledge in the field of maintenance.Many enterprises are operating a cost controlled maintenance management meaning that the maintenance section is just controlled by the money which is available in the budget. In this case the consequences for production and other functions will not be taken into consideration due to the maintenance work.

Comparison of actual maintenance costs against the maintenance budget will be an inherent part of the cost control system. Should adverse variances occur due, for example, to severe damage to an item of plant caused by an inefficient operator, the best course of action is for the maintenance engineer to apply for a supplementary addition to his budget. This approach is to be preferred to the alternative of `delay tactics', where it is hope that savings will be created in other areas, with the results that at the end of the year total actual costs compare favourably with the budget costs. This could mean that the required level of maintenance on other machines has not been completed, to the possible detriment of the machinery's effectiveness in the future.In these circumstances, it is important that all interested parties appreciate the difficulties associated with the maintenance function and as a result the engineer/manager and the management accountant co-operate in developing a system which helps maintenance management to be more efficient. This principle must apply both at the budget preparation stage as well as the implementation stage, i.e. in the analysis of variances and consideration of the various alternative courses of action.

When excessive maintenance occurs due to bad machinery design, it is equally important that there should be effective feedback of the appropriate information to the manufacturer and/or designer.

1.2.2 Cost or Result Controlled Maintenance

The cost controlled maintenance is not connected to modern maintenance. According to one of the maintenance objective is to "keep up planned availability performance to the lowest cost possible" which means that it is the long term results which must be taken into consideration. The maintenance cost must be put in relationship with the planned availability performance.The reason for why maintenance has been treated as a cost controlled activity is often that technicians have had some difficulties to measure the investments in maintenance in total economic terms. It is very easy to find the cost of maintenance but it is difficult to see the results.

The maintenance costs can be varying from organisation to organisation and divided into two categories:-

I. Direct maintenance costs.

a) Personnel cost for those carrying out the maintenance work.b) Costs for lubricants, paint, gaskets, and other materials which are consumed in

connection with maintenance. c) Cost of administrative systems connected with maintenance.d) Costs for premises, equipment and other services used by the maintenance

department.e) Cost of work carried out by third parties and companies.f) Costs for rebuilding etc., intended to reduce, simplify or eleminate maintenance.

II. Indirect maintenance cost

Indirect maintenance cost is loss of revenue as a result of interruptions to production due to inadequate maintenance. For example a shut down in a large process industry can cost tens of thousands of dollars per hour, twenty-four hours loss of service of a large ship can lead to losses of hundreds of thousands of dollars.In results controlled maintenance management it is always the direct maintenance costs put into relationship to the indirect costs.

Maintenance and its results can be like an iceberg was the biggest part is invisible under the water level and only a small part is visible above the surface. The visible part is representing the maintenance costs as the invisible part is representing the costs for different factors influenced by maintenance.

1.2.3 Four Types of Cost in Maintenance

I. Cost to replace or repairII. Losses of outputIII. Delayed shipmentIV. Scrap and rework

1.3 Describeworkplacesafety.

Defnition

Workplace is the location at or from which an employee ordinarily performs the duties of his or her position and, in the case of an employee whose duties are of an itinerant nature, the actual building to which the employee returns to prepare and/or submit reports, etc., and where other administrative matters pertaining to the employee's employment are conducted.

Workplace safety is essential for providing a safe environment in which employees can work with minimal risk to their health. On-the-job accidents can cause injuries and death. Preventing these accidents requires the effort of all employees in the organization. Numerous workplace of risks exist, including dangers resulting from human errors and mechanical malfunctions. An organization must use a combination of safety training and safety protocols to prevent as many employee injuries as possible.

Safe and healthy environment in the workplace benefits everybody.  When people feel safe and are healthy their productivity at work increases.  This in turn benefits the company.  The number of work hours lost due to illness and injuries is also decreased in a safe and healthy workplace. Everyone will be more productive.

Safe and healthy work atmosphere assist in reducing the risk of avoidable problems.  It is in the interest of the company to provide safe and healthy workplace if it needs to avoid dealing with complaints or lawsuits from its workers arising from injuries while at job.

Companies emphasizing on tidy, organized and safe work environment help boost the individual and the company’s morale as a whole. This encourages everyone working there to do their best and feel good about getting the job done.

Ensuring the safety at workplace does not require huge investment of time or money or other resources. All you need is to establish the basic framework and pathways to achieve the desired targets. Everyone working in the company should be made aware of their responsibility to follow the local policies, provided training with regular updates then the whole environment will become safe and healthy. When individuals practice the safety at workplace on daily basis it becomes a second nature. Workers should be encouraged to report near misses which are critical in developing new strategies and safeguards against possible mishaps. Safe and healthy workplace leads to confident and productive workers.

Prosperous companies make efforts to ensure their workers safety as these companies have realized the importance of healthy and happy workers.

Working in a clean, healthy environment can have a major effect on your employees. They may love their job, but on those bad days, a bright and clean workspace can help them through it and keep them productive. In a dingy or cluttered workspace, bad days and problems seem to fester a lot longer. A clean workspace can have a major impact on how people feel and behave in the workplace

1.3.1 Identifythebenefitcleanandsafeworkingenvironment.

A clean workplace improves air quality, and that keeps everyone cutting down on sick days and absenteeism. Your workers will have more energy and feel more creative. Just the simple task of cleaning can improve performance and boost business.

When people feel better about their environment, they get along better. If you are having issues with communication in the workplace and people seem to be bickering with co-workers, try making the space cleaner. The fresh change may be just what everyone needs to feel better and try harder to get along with one another in the workplace

Benefits

healthy workers are productive and raise healthy families; thus healthy workers are a key strategy in overcoming poverty.workplace health risks are higher in the informal sector and small industries which are key arenas of action on poverty alleviation, where people can work their way out of poverty.safe workplaces contribute to sustainable development, which is the key to poverty reduction.the processes of protecting workers, surrounding communities and the environment for future generations have important common elements, such as pollution control and exposure reduction.much pollution and many environmental exposures that are hazardous to health arise from industrial processes, that can be beneficially influenced by occupational health and safety programmes.occupational safety and health can contribute to improving the employability of workers, through workplace (re)design, maintenance of a healthy and safe work environment, training and retraining, assessment of work demands, medical diagnosis, health screening and assessment of functional capacities.occupational health is fundamental to public health, for it is increasingly clear that major diseases (e.g. AIDS, heart disease, cancer) need workplace wellness programmes.

Benefits of promoting a healthy workplace

To the organisation

a well-managed health and safety programmea positive and caring imageimproved staff moralereduced staff turnoverreduced absenteeismincreased productivityreduced health care/insurance costsreduced risk of fines and litigation

To the employee

a safe and healthy work environmentenhanced self-esteemreduced stressimproved moraleincreased job satisfactionincreased skills for health protectionimproved healthimproved sense of well-being

1.3.2 Explaintheimportantof personal protectionequipments.Introduction

Hazards exist in every workplace in many different forms: sharp edges, falling objects, flying sparks, chemicals, noise and a myriad of other potentially dangerous situations. The Occupational Safety and Health Administration (OSHA) requires that employers protect their employees from workplace hazards that can cause injury.

Controlling a hazard at its source is the best way to protect employees. Depending on the hazard or workplace conditions, OSHA recommends the use of engineering or work practice controls to manage or eliminate hazards to the greatest extent possible. For example, building a barrier between the hazard and the employees is an engineering control; changing the way in which employees perform their work is a work practice control.

When engineering, work practice and administrative controls are not feasible or do not provide sufficient protection, employers must provide personal protective equipment (PPE) to their employees and ensure its use. Personal protective equipment, commonly referred to as "PPE", is equipment worn to minimize exposure to a variety of hazards. Examples of PPE include such items as gloves, foot and eye protection, protective hearing devices (earplugs, muffs) hard hats, respirators and full body suits.

This guide will help both employers and employees do the following:

Understand the types of PPE.

Know the basics of conducting a "hazard assessment" of the workplace. Select appropriate PPE for a variety of circumstances. Understand what kind of training is needed in the proper use and care of PPE.

The Requirement for PPE

To ensure the greatest possible protection for employees in the workplace, the cooperative efforts of both employers and employees will help in establishing and maintaining a safe and healthful work environment.

In general, employers are responsible for:

Performing a "hazard assessment" of the workplace to identify and control physical and health hazards.

Identifying and providing appropriate PPE for employees. Training employees in the use and care of the PPE. Maintaining PPE, including replacing worn or damaged PPE. Periodically reviewing, updating and evaluating the effectiveness of the PPE program.

In general, employees should:

Properly wear PPE, Attend training sessions on PPE, Care for, clean and maintain PPE, and Inform a supervisor of the need to repair or replace PPE.

Specific requirements for PPE are presented in many different OSHA standards, published in 29 CFR. Some standards require that employers provide PPE at no cost to the employee while others simply state that the employer must provide PPE. Appendix A at page 40 lists those standards that require the employer to provide PPE and those that require the employer to provide PPE at no cost to the employee.

The Hazard Assessment

A first critical step in developing a comprehensive safety and health program is to identify physical and health hazards in the workplace. This process is known as a "hazard assessment." Potential hazards may be physical or health-related and a comprehensive hazard assessment should identify hazards in both categories. Examples of physical hazards include moving objects, fluctuating temperatures, high intensity lighting, rolling or pinching objects, electrical connections and sharp edges. Examples of health hazards include overexposure to harmful dusts, chemicals or radiation.

The hazard assessment should begin with a walk-through survey of the facility to develop a list of potential hazards in the following basic hazard categories:

Impact, Penetration, Compression (roll-over), Chemical, Heat/cold, Harmful dust, Light (optical) radiation, and Biologic.

In addition to noting the basic layout of the facility and reviewing any history of occupational illnesses or injuries, things to look for during the walk-through survey include:

Sources of electricity. Sources of motion such as machines or processes where movement may exist that could

result in an impact between personnel and equipment. Sources of high temperatures that could result in burns, eye injuries or fire. Types of chemicals used in the workplace. Sources of harmful dusts. Sources of light radiation, such as welding, brazing, cutting, furnaces, heat treating, high

intensity lights, etc. The potential for falling or dropping objects. Sharp objects that could poke, cut, stab or puncture. Biologic hazards such as blood or other potentially infected material.

When the walk-through is complete, the employer should organize and analyze the data so that it may be efficiently used in determining the proper types of PPE required at the worksite. The employer should become aware of the different types of PPE available and the levels of protection offered. It is definitely a good idea to select PPE that will provide a level of protection greater than the minimum required to protect employees from hazards.

The workplace should be periodically reassessed for any changes in conditions, equipment or operating procedures that could affect occupational hazards. This periodic reassessment should also include a review of injury and illness records to spot any trends or areas of concern and taking appropriate corrective action. The suitability of existing PPE, including an evaluation of its condition and age, should be included in the reassessment.

Documentation of the hazard assessment is required through a written certification that includes the following information:

Identification of the workplace evaluated; Name of the person conducting the assessment; Date of the assessment; and Identification of the document certifying completion of the hazard assessment.

Selecting PPE

All PPE clothing and equipment should be of safe design and construction, and should be maintained in a clean and reliable fashion. Employers should take the fit and comfort of PPE into consideration when selecting appropriate items for their workplace. PPE that fits well and is comfortable to wear will encourage employee use of PPE. Most protective devices are available in multiple sizes and care should be taken to select the proper size for each employee. If several different types of PPE are worn together, make sure they are compatible. If PPE does not fit properly, it can make the difference between being safely covered or dangerously exposed. It may not provide the level of protection desired and may discourage employee use.

OSHA requires that many categories of PPE meet or be equivalent to standards developed by the American National Standards Institute (ANSI). ANSI has been preparing safety standards since the 1920s, when the first safety standard was approved to protect the heads and eyes of industrial workers. Employers who need to provide PPE in the categories listed below must make certain that any new equipment procured meets the cited ANSI standard. Existing PPE stocks must meet the ANSI standard in effect at the time of its manufacture or provide protection equivalent to PPE manufactured to the ANSI criteria. Employers should inform employees who provide their own PPE of the employer's selection decisions and ensure that any employee-owned PPE used in the workplace conforms to the employer's criteria, based on the hazard assessment, OSHA requirements and ANSI standards. OSHA requires PPE to meet the following ANSI standards:

Eye and Face Protection: ANSI Z87.1-1989 (USA Standard for Occupational and Educational Eye and Face Protection).

Head Protection: ANSI Z89.1-1986. Foot Protection: ANSI Z41.1-1991.

For hand protection, there is no ANSI standard for gloves but OSHA recommends that selection be based upon the tasks to be performed and the performance and construction characteristics of the glove material. For protection against chemicals, glove selection must be based on the chemicals encountered, the chemical resistance and the physical properties of the glove material.

Training Employees in the Proper Use of PPE

Employers are required to train each employee who must use PPE. Employees must be trained to know at least the following:

When PPE is necessary. What PPE is necessary. How to properly put on, take off, adjust and wear the PPE. The limitations of the PPE. Proper care, maintenance, useful life and disposal of PPE.

Employers should make sure that each employee demonstrates an understanding of the PPE training as well as the ability to properly wear and use PPE before they are allowed to perform work requiring the use of the PPE. If an employer believes that a previously trained employee is not demonstrating the proper understanding and skill level in the use of PPE, that employee should receive retraining. Other situations that require additional or retraining of employees

include the following circumstances: changes in the workplace or in the type of required PPE that make prior training obsolete.

The employer must document the training of each employee required to wear or use PPE by preparing a certification containing the name of each employee trained, the date of training and a clear identification of the subject of the certification.

Eye and Face Protection

Employees can be exposed to a large number of hazards that pose danger to their eyes and face. OSHA requires employers to ensure that employees have appropriate eye or face protection if they are exposed to eye or face hazards from flying particles, molten metal, liquid chemicals, acids or caustic liquids, chemical gases or vapors, potentially infected material or potentially harmful light radiation.

Many occupational eye injuries occur because workers are not wearing any eye protection while others result from wearing improper or poorly fitting eye protection. Employers must be sure that their employees wear appropriate eye and face protection and that the selected form of protection is appropriate to the work being performed and properly fits each worker exposed to the hazard.

Prescription LensesEveryday use of prescription corrective lenses will not provide adequate protection against most occupational eye and face hazards, so employers must make sure that employees with corrective lenses either wear eye protection that incorporates the prescription into the design or wear additional eye protection over their prescription lenses. It is important to ensure that the protective eyewear does not disturb the proper positioning of the prescription lenses so that the employee's vision will not be inhibited or limited. Also, employees who wear contact lenses must wear eye or face PPE when working in hazardous conditions.

Eye Protection for Exposed WorkersOSHA suggests that eye protection be routinely considered for use by carpenters, electricians, machinists, mechanics, millwrights, plumbers and pipefitters, sheetmetal workers and tinsmiths, assemblers, sanders, grinding machine operators, sawyers, welders, laborers, chemical process operators and handlers, and timber cutting and logging workers. Employers of workers in other job categories should decide whether there is a need for eye and face PPE through a hazard assessment.

Examples of potential eye or face injuries include:

Dust, dirt, metal or wood chips entering the eye from activities such as chipping, grinding, sawing, hammering, the use of power tools or even strong wind forces.

Chemical splashes from corrosive substances, hot liquids, solvents or other hazardous solutions.

Objects swinging into the eye or face, such as tree limbs, chains, tools or ropes. Radiant energy from welding, harmful rays from the use of lasers or other radiant light

(as well as heat, glare, sparks, splash and flying particles).

Types of Eye Protection

Selecting the most suitable eye and face protection for employees should take into consideration the following elements:

Ability to protect against specific workplace hazards. Should fit properly and be reasonably comfortable to wear. Should provide unrestricted vision and movement. Should be durable and cleanable. Should allow unrestricted functioning of any other required PPE.

The eye and face protection selected for employee use must clearly identify the manufacturer. Any new eye and face protective devices must comply with ANSI Z87.1-1989 or be at least as effective as this standard requires. Any equipment purchased before this requirement took effect on July 5, 1994, must comply with the earlier ANSI Standard (ANSI Z87.1-1968) or be shown to be equally effective.

An employer may choose to provide one pair of protective eyewear for each position rather than individual eyewear for each employee. If this is done, the employer must make sure that employees disinfect shared protective eyewear after each use. Protective eyewear with corrective lenses may only be used by the employee for whom the corrective prescription was issued and may not be shared among employees.

Some of the most common types of eye and face protection include the following:

Safety spectacles. These protective eyeglasses have safety frames constructed of metal or plastic and impact-resistant lenses. Side shields are available on some models.

Goggles. These are tight-fitting eye protection that completely cover the eyes, eye sockets and the facial area immediately surrounding the eyes and provide protection from impact, dust and splashes. Some goggles will fit over corrective lenses.

Welding shields. Constructed of vulcanized fiber or fiberglass and fitted with a filtered lens, welding shields protect eyes from burns caused by infrared or intense radiant light; they also protect both the eyes and face from flying sparks, metal spatter and slag chips produced during welding, brazing, soldering and cutting operations. OSHA requires filter lenses to have a shade number appropriate to protect against the specific hazards of the work being performed in order to protect against harmful light radiation.

Laser safety goggles. These specialty goggles protect against intense concentrations of light produced by lasers. The type of laser safety goggles an employer chooses will depend upon the equipment and operating conditions in the workplace.

Face shields. These transparent sheets of plastic extend from the eyebrows to below the chin and across the entire width of the employee's head. Some are polarized for glare protection. Face shields protect against nuisance dusts and potential splashes or sprays of hazardous liquids but will not provide adequate protection against impact hazards. Face shields used in combination with goggles or safety spectacles will provide additional protection against impact hazards.

Each type of protective eyewear is designed to protect against specific hazards. Employers can identify the specific workplace hazards that threaten employees' eyes and faces by completing a hazard assessment as outlined in the earlier section.

Welding Operations

The intense light associated with welding operations can cause serious and sometimes permanent eye damage if operators do not wear proper eye protection. The intensity of light or radiant energy produced by welding, cutting or brazing operations varies according to a number of factors including the task producing the light, the electrode size and the arc current. The following table shows the minimum protective shades for a variety of welding, cutting and brazing operations in general industry and in the shipbuilding industry.

Table 1Filter Lenses for Protection Against Radiant Energy

Operations Electrode size in 1/32" (0.8mm) Arc current Minimum* protective shade

Shielded metal arc welding < 33 - 55 - 8> 8

< 6060 - 160160 - 250250 - 550

781011

Gas metal arc weldingand flux coredarc welding

< 6060 - 160160 - 250250 - 500

7101010

Gas tungstenarc welding

< 5050 - 150150 - 500

8810

Air carbon (light) < 500 10

Arc cutting (heavy) 500 - 1,000 11

Plasma arc welding < 2020 - 100100 - 400400 - 800

681011

Plasma arc cutting (light)**(medium)**(heavy)**

< 300300 - 400400 - 800

8910

Torch brazing 3

Torch soldering 2

Carbon arc welding 14

Table 2Filter Lenses for Protection Against Radiant Energy

Operations Plate thickness inches Plate thickness mm Minimum* protective shade

Gas welding:Light

< 1/8 < 3.2 4

Gas welding:Medium

1/8 - 1/2 3.2 - 12.7 5

Gas welding:Heavy

> 1/2 > 12.7 6

Oxygen cutting:Light

< 1 < 25 3

Oxygen cutting: Medium 1 - 6 25 - 150 4

Oxygen cutting:Heavy

> 6 > 150 5

Source: 29 CFR 1910.133(a)(5).

* As a rule of thumb, start with a shade that is too dark to see the weld zone. Then go to a lighter shade which gives sufficient view of the weld zone without going below the minimum. In oxyfuel gas welding or cutting where the torch produces a high yellow light, it is desirable to use a filter lens that absorbs the yellow or sodium line in the visible light of the (spectrum) operation.

** These values apply where the actual arc is clearly seen. Experience has shown that lighter filters may be used when the arc is hidden by the workpiece.

The construction industry has separate requirements for filter lens protective levels for specific types of welding operations, as indicated in the table below:

Laser Operations

Laser light radiation can be extremely dangerous to the unprotected eye and direct or reflected beams can cause permanent eye damage. Laser retinal burns can be painless, so it is essential that all personnel in or around laser operations wear appropriate eye protection.

Laser safety goggles should protect for the specific wavelength of the laser and must be of sufficient optical density for the energy involved. Safety goggles intended for use with laser beams must be labeled with the laser wavelengths for which they are intended to be used, the optical density of those wavelengths and the visible light transmission.

The table below lists maximum power or energy densities and appropriate protection levels for optical densities 5 through 8.

Table 3Selecting Laser Safety Glass

Intensity, CW maximum power density (watts/cm2)

Attenuation

Optical density (O.D.)

Attenuation factor

10-2 5 105

10-1 6 106

1.0 7 107

10.0 8 108

Source: 29 CFR 1926.102(b)(2).

Head Protection

Protecting employees from potential head injuries is a key element of any safety program. A head injury can impair an employee for life or it can be fatal. Wearing a safety helmet or hard hat is one of the easiest ways to protect an employee's head from injury. Hard hats can protect employees from impact and penetration hazards as well as from electrical shock and burn hazards.

Employers must ensure that their employees wear head protection if any of the following apply:

Objects might fall from above and strike them on the head; They might bump their heads against fixed objects, such as exposed pipes or beams; or There is a possibility of accidental head contact with electrical hazards.

Some examples of occupations in which employees should be required to wear head protection include construction workers, carpenters, electricians, linemen, plumbers and pipefitters, timber and log cutters, welders, among many others. Whenever there is a danger of objects falling from above, such as working below others who are using tools or working under a conveyor belt, head protection must be worn. Hard hats must be worn with the bill forward to protect employees properly.

In general, protective helmets or hard hats should do the following:

Resist penetration by objects. Absorb the shock of a blow. Be water-resistant and slow burning. Have clear instructions explaining proper adjustment and replacement of the suspension

and headband.

Hard hats must have a hard outer shell and a shock-absorbing lining that incorporates a headband and straps that suspend the shell from 1 to 1 1/4 inches (2.54 cm to 3.18 cm) away from the head. This type of design provides shock absorption during an impact and ventilation during normal wear.

Protective headgear must meet ANSI Standard Z89.1-1986 (Protective Headgear for Industrial Workers) or provide an equivalent level of protection. Helmets purchased before July 5, 1994 must comply with the earlier ANSI Standard (Z89.1-1969) or provide equivalent protection.

Types of Hard Hats

There are many types of hard hats available in the marketplace today. In addition to selecting protective headgear that meets ANSI standard requirements, employers should ensure that employees wear hard hats that provide appropriate protection against potential workplace hazards. It is important for employers to understand all potential hazards when making this selection, including electrical hazards. This can be done through a comprehensive hazard analysis and an awareness of the different types of protective headgear available.

Hard hats are divided into three industrial classes:

Class A hard hats provide impact and penetration resistance along with limited voltage protection (up to 2,200 volts).

Class B hard hats provide the highest level of protection against electrical hazards, with high-voltage shock and burn protection (up to 20,000 volts). They also provide protection from impact and penetration hazards by flying/falling objects.

Class C hard hats provide lightweight comfort and impact protection but offer no protection from electrical hazards.

Another class of protective headgear on the market is called a “bump hat," designed for use in areas with low head clearance. They are recommended for areas where protection is needed from head bumps and lacerations. These are not designed to protect against falling or flying objects and are not ANSI approved. It is essential to check the type of hard hat employees are using to ensure that the equipment provides appropriate protection. Each hat should bear a label inside the shell that lists the manufacturer, the ANSI designation and the class of the hat.

Size and Care Considerations

Head protection that is either too large or too small is inappropriate for use, even if it meets all other requirements. Protective headgear must fit appropriately on the body and for the head size of each individual. Most protective headgear comes in a variety of sizes with adjustable headbands to ensure a proper fit (many adjust in 1/8-inch increments). A proper fit should allow sufficient clearance between the shell and the suspension system for ventilation and distribution of an impact. The hat should not bind, slip, fall off or irritate the skin.

Some protective headgear allows for the use of various accessories to help employees deal with changing environmental conditions, such as slots for earmuffs, safety glasses, face shields and mounted lights. Optional brims may provide additional protection from the sun and some hats have channels that guide rainwater away from the face. Protective headgear accessories must not compromise the safety elements of the equipment.

Periodic cleaning and inspection will extend the useful life of protective headgear. A daily inspection of the hard hat shell, suspension system and other accessories for holes, cracks, tears or other damage that might compromise the protective value of the hat is essential. Paints, paint thinners and some cleaning agents can weaken the shells of hard hats and may eliminate electrical resistance. Consult the helmet manufacturer for information on the effects of paint and cleaning materials on their hard hats. Never drill holes, paint or apply labels to protective headgear as this may reduce the integrity of the protection. Do not store protective headgear in direct sunlight, such as on the rear window shelf of a car, since sunlight and extreme heat can

damage them.

Hard hats with any of the following defects should be removed from service and replaced:

Perforation, cracking, or deformity of the brim or shell; Indication of exposure of the brim or shell to heat, chemicals or ultraviolet light and other

radiation (in addition to a loss of surface gloss, such signs include chalking or flaking).

Always replace a hard hat if it sustains an impact, even if damage is not noticeable. Suspension systems are offered as replacement parts and should be replaced when damaged or when excessive wear is noticed. It is not necessary to replace the entire hard hat when deterioration or tears of the suspension systems are noticed.

Foot and Leg Protection

Employees who face possible foot or leg injuries from falling or rolling objects or from crushing or penetrating materials should

wear protective footwear. Also, employees whose work involves exposure to hot substances or corrosive or poisonous materials must have protective gear to cover exposed body parts, including legs and feet. If an employee's feet may be exposed to electrical hazards, non-conductive footwear should be worn. On the other hand, workplace exposure to static electricity may necessitate the use of conductive footwear.

Examples of situations in which an employee should wear foot and/or leg protection include:

When heavy objects such as barrels or tools might roll onto or fall on the employee's feet;Working with sharp objects such as nails or spikes that could pierce the soles or uppers of ordinary shoes;Exposure to molten metal that might splash on feet or legs;Working on or around hot, wet or slippery surfaces; and

Working when electrical hazards are present.

Safety footwear must meet ANSI minimum compression and impact performance standards in ANSI Z41-1991 (American National Standard for Personal Protection-Protective Footwear) or provide equivalent protection. Footwear purchased before July 5, 1994, must meet or provide equivalent protection to the earlier ANSI Standard (ANSI Z41.1-1967). All ANSI approved footwear has a protective toe and offers impact and compression protection. But the type and amount of protection is not always the same. Different footwear protects in different ways. Check the product's labeling or consult the manufacturer to make sure the footwear will protect the user from the hazards they face.

Foot and leg protection choices include the following:

Leggings protect the lower legs and feet from heat hazards such as molten metal or welding sparks. Safety snaps allow leggings to be removed quickly.

Metatarsal guards protect the instep area from impact and compression. Made of aluminum, steel, fiber or plastic, these guards may be strapped to the outside of shoes.

Toe guards fit over the toes of regular shoes to protect the toes from impact and compression hazards. They may be made of steel, aluminum or plastic.

Combination foot and shin guards protect the lower legs and feet, and may be used in combination with toe guards when greater protection is needed.

Safety shoes have impact-resistant toes and heat-resistant soles that protect the feet against hot work surfaces common in roofing, paving and hot metal industries. The metal insoles of some safety shoes protect against puncture wounds. Safety shoes may also be designed to be electrically conductive to prevent the buildup of static electricity in areas with the potential for explosive atmospheres or nonconductive to protect workers from workplace electrical hazards.

Special Purpose Shoes

Electrically conductive shoes provide protection against the buildup of static electricity. Employees working in explosive and hazardous locations such as explosives manufacturing facilities or grain elevators must wear conductive shoes to reduce the risk of static electricity buildup on the body that could produce a spark and cause an explosion or fire. Foot powder should not be used in conjunction with protective conductive footwear because it provides insulation, reducing the conductive ability of the shoes. Silk, wool and nylon socks can produce static electricity and should not be worn with conductive footwear. Conductive shoes must be removed when the task requiring their use is completed. Note: Employees exposed to electrical hazards must never wear conductive shoes.

Electrical hazard, safety-toe shoes are nonconductive and will prevent the wearers' feet from completing an electrical circuit to the ground. These shoes can protect against open circuits of up to 600 volts in dry conditions and should be used in conjunction with other insulating equipment and additional precautions to reduce the risk of a worker becoming a path for hazardous electrical energy. The insulating protection of electrical hazard, safety-toe shoes may be compromised if the shoes become wet, the soles are worn through, metal particles become embedded in the sole or heel, or workers touch conductive, grounded items. Note: Nonconductive footwear must not be used in explosive or hazardous locations.

Foundry ShoesIn addition to insulating the feet from the extreme heat of molten metal, foundry shoes keep hot metal from lodging in shoe eyelets, tongues or other shoe parts. These snug-fitting leather or leather-substitute shoes have leather or rubber soles and rubber heels. All foundry shoes must have built-in safety toes.

Care of Protective FootwearAs with all protective equipment, safety footwear should be inspected prior to each use. Shoes and leggings should be checked for wear and tear at reasonable intervals. This includes looking for cracks or holes, separation of materials, broken buckles or laces. The soles of shoes should be checked for pieces of metal or other embedded items that could present electrical or tripping

hazards. Employees should follow the manufacturers' recommendations for cleaning and maintenance of protective footwear.

Hand and Arm Protection

If a workplace hazard assessment reveals that employees face potential injury to hands and arms that cannot be eliminated through engineering and work practice controls, employers must ensure that employees wear appropriate protection. Potential hazards include skin absorption of harmful substances, chemical or thermal burns, electrical dangers, bruises, abrasions, cuts, punctures, fractures and amputations. Protective equipment includes gloves, finger guards and arm coverings or elbow-length gloves.

Employers should explore all possible engineering and work practice controls to eliminate hazards and use PPE to provide additional protection against hazards that cannot be completely eliminated through other means. For example, machine guards may eliminate a hazard. Installing a barrier to prevent workers from placing their hands at the point of contact between a table saw blade and the item being cut is another method.

Types of Protective Gloves

There are many types of gloves available today to protect against a wide variety of hazards. The nature of the hazard and the operation involved will affect the selection of gloves. The variety of potential occupational hand injuries makes selecting the right pair of gloves challenging. It is essential that employees use gloves specifically designed for the hazards and tasks found in their workplace because gloves designed for one function may not protect against a different function even though they may appear to be an appropriate protective device.

The following are examples of some factors that may influence the selection of protective gloves for a workplace.

Type of chemicals handled. Nature of contact (total immersion, splash, etc.). Duration of contact. Area requiring protection (hand only, forearm, arm). Grip requirements (dry, wet, oily). Thermal protection. Size and comfort. Abrasion/resistance requirements. Gloves made from a wide variety of materials are designed for many types of workplace

hazards. In general, gloves fall into four groups: Gloves made of leather, canvas or metal mesh; Fabric and coated fabric gloves; Chemical- and liquid-resistant gloves;

Insulating rubber gloves (See 29 CFR 1910.137 and the following section on electrical protective equipment for detailed requirements on the selection, use and care of insulating rubber gloves).

Leather, Canvas or Metal Mesh GlovesSturdy gloves made from metal mesh, leather or canvas provide protection against cuts and burns. Leather or canvass gloves also protect against sustained heat.

Leather gloves protect against sparks, moderate heat, blows, chips and rough objects. Aluminized gloves provide reflective and insulating protection against heat and require

an insert made of synthetic materials to protect against heat and cold. Aramid fiber gloves protect against heat and cold, are cut - and abrasive - resistant and

wear well. Synthetic gloves of various materials offer protection against heat and cold, are cut - and

abrasive - resistant and may withstand some diluted acids. These materials do not stand up against alkalis and solvents.

Fabric and Coated Fabric GlovesFabric and coated fabric gloves are made of cotton or other fabric to provide varying degrees of protection.

Fabric gloves protect against dirt, slivers, chafing and abrasions. They do not provide sufficient protection for use with rough, sharp or heavy materials. Adding a plastic coating will strengthen some fabric gloves.

Coated fabric gloves are normally made from cotton flannel with napping on one side. By coating the unnapped side with plastic, fabric gloves are transformed into general-purpose hand protection offering slip-resistant qualities. These gloves are used for tasks ranging from handling bricks and wire to chemical laboratory containers. When selecting gloves to protect against chemical exposure hazards, always check with the manufacturer or review the manufacturer's product literature to determine the gloves' effectiveness against specific workplace chemicals and conditions.

Chemical - and Liquid - Resistant GlovesChemical-resistant gloves are made with different kinds of rubber: natural, butyl, neoprene, nitrile and fluorocarbon (viton); or various kinds of plastic: polyvinyl chloride (PVC), polyvinyl alcohol and polyethylene. These materials can be blended or laminated for better performance. As a general rule, the thicker the glove material, the greater the chemical resistance but thick gloves may impair grip and dexterity, having a negative impact on safety.

Some examples of chemical-resistant gloves include:

Butyl gloves are made of a synthetic rubber and protect against a wide variety of chemicals, such as peroxide, rocket fuels, highly corrosive acids (nitric acid, sulfuric acid, hydrofluoric acid and red-fuming nitric acid), strong bases, alcohols, aldehydes, ketones, esters and nitrocompounds. Butyl gloves also resist oxidation, ozone corrosion and abrasion, and remain flexible at low temperatures. Butyl rubber does not perform well with aliphatic and aromatic hydrocarbons and halogenated solvents.

Natural (latex) rubber gloves are comfortable to wear, which makes them a popular general-purpose glove. They feature outstanding tensile strength, elasticity and temperature resistance. In addition to resisting abrasions caused by grinding and polishing, these gloves protect workers' hands from most water solutions of acids, alkalis, salts and ketones. Latex gloves have caused allergic reactions in some individuals and may not be appropriate for all employees. Hypoallergenic gloves, glove liners and powderless gloves are possible alternatives for workers who are allergic to latex gloves.

Neoprene gloves are made of synthetic rubber and offer good pliability, finger dexterity, high density and tear resistance. They protect against hydraulic fluids, gasoline, alcohols, organic acids and alkalis. They generally have chemical and wear resistance properties superior to those made of natural rubber.

Nitrile gloves are made of a copolymer and provide protection from chlorinated solvents such as trichloroethylene and perchloroethylene. Although intended for jobs requiring dexterity and sensitivity, nitrile gloves stand up to heavy use even after prolonged exposure to substances that cause other gloves to deteriorate. They offer protection when working with oils, greases, acids, caustics and alcohols but are generally not recommended for use with strong oxidizing agents, aromatic solvents, ketones and acetates.

Care of Protective Gloves

Protective gloves should be inspected before each use to ensure that they are not torn, punctured or made ineffective in any way. A visual inspection will help detect cuts or tears but a more thorough inspection by filling the gloves with water and tightly rolling the cuff towards the fingers will help reveal any pinhole leaks. Gloves that are discolored or stiff may also indicate deficiencies caused by excessive use or degradation from chemical exposure.

Any gloves with impaired protective ability should be discarded and replaced. Reuse of chemical-resistant gloves should be evaluated carefully, taking into consideration the absorptive qualities of the gloves. A decision to reuse chemically-exposed gloves should take into consideration the toxicity of the chemicals involved and factors such as duration of exposure, storage and temperature.

Body Protection

Employees who face possible bodily injury of any kind that cannot be eliminated through engineering, work practice or administrative controls, must wear appropriate body protection while performing their jobs. In addition to cuts and radiation, the following are examples of workplace hazards that could cause bodily injury:

Temperature extremes; Hot splashes from molten metals and other hot liquids; Potential impacts from tools, machinery and materials; Hazardous chemicals.

There are many varieties of protective clothing available for specific hazards. Employers are required to ensure that their employees wear personal protective equipment only for the parts of the body exposed to possible injury. Examples of body protection include laboratory coats, coveralls, vests, jackets, aprons, surgical gowns and full body suits.

If a hazard assessment indicates a need for full body protection against toxic substances or harmful physical agents, the clothing should be carefully inspected before each use, it must fit each worker properly and it must function properly and for the purpose for which it is intended.

Protective clothing comes in a variety of materials, each effective against particular hazards, such as:

Paper-like fiber used for disposable suits provide protection against dust and splashes. Treated wool and cotton adapts well to changing temperatures, is comfortable, and fire-

resistant and protects against dust, abrasions and rough and irritating surfaces. Duck is a closely woven cotton fabric that protects against cuts and bruises when

handling heavy, sharp or rough materials. Leather is often used to protect against dry heat and flames. Rubber, rubberized fabrics, neoprene and plastics protect against certain chemicals

and physical hazards. When chemical or physical hazards are present, check with the clothing manufacturer to ensure that the material selected will provide protection against the specific hazard.

Hearing Protection

Determining the need to provide hearing protection for employees can be challenging. Employee exposure to excessive noise depends upon a number of factors, including:

The loudness of the noise as measured in decibels (dB). The duration of each employee's exposure to the noise. Whether employees move between work areas with different noise levels. Whether noise is generated from one or multiple sources.

Generally, the louder the noise, the shorter the exposure time before hearing protection is required. For instance, employees may be exposed to a noise level of 90 dB for 8 hours per day (unless they experience a Standard Threshold Shift) before hearing protection is required. On the other hand, if the noise level reaches 115 dB hearing protection is required if the anticipated exposure exceeds 15 minutes.

For a more detailed discussion of the requirements for a comprehensive hearing conservation program, see OSHA Publication 3074 (2002), “Hearing Conservation" or refer to the OSHA standard at 29 CFR 1910.95, Occupational Noise Exposure, section (c).

Table 5, below, shows the permissible noise exposures that require hearing protection for employees exposed to occupational noise at specific decibel levels for specific time periods. Noises are considered continuous if the interval between occurrences of the maximum noise

level is one second or less. Noises not meeting this definition are considered impact or impulse noises (loud momentary explosions of sound) and exposures to this type of noise must not exceed 140 dB. Examples of situations or tools that may result in impact or impulse noises are powder-actuated nail guns, a punch press or drop hammers.

Table 3Permissible Noise Exposures 1/4 or less 115

Duration per day,in hours

Sound level in dB*

8 90

6 92

4 95

3 97

2 100

11/25

102

1 105

1/2 110

1/4 or less 11

*When measured on the A scale of a standard sound level meter at slow response.Source: 29 CFR 1910.95,Table G-16.

If engineering and work practice controls do not lower employee exposure to workplace noise to acceptable levels, employees must wear appropriate hearing protection. It is important to understand that hearing protectors reduce only the amount of noise that gets through to the ears. The amount of this reduction is referred to as attenuation, which differs according to the type of hearing protection used and how well it fits. Hearing protectors worn by employees must reduce an employee's noise exposure to within the acceptable limits noted in Table 5. Refer to Appendix B of 29 CFR 1910.95, Occupational Noise Exposure, for detailed information on methods to estimate the attenuation effectiveness of hearing protectors based on the device's noise reduction rating (NRR). Manufacturers of hearing protection devices must display the device's NRR on the product packaging. If employees are exposed to occupational noise at or above 85 dB averaged over an eight-hour period, the employer is required to institute a hearing conservation program that includes regular testing of employees' hearing by qualified professionals. Refer to 29 CFR 1910.95(c) for a description of the requirements for a hearing conservation program.

Some types of hearing protection include:

Single-use earplugs are made of waxed cotton, foam, silicone rubber or fiberglass wool. They are self-forming and, when properly inserted, they work as well as most molded earplugs.

Pre-formed or molded earplugs must be individually fitted by a professional and can be disposable or reusable. Reusable plugs should be cleaned after each use.

Earmuffs require a perfect seal around the ear. Glasses, facial hair, long hair or facial movements such as chewing may reduce the protective value of earmuffs.

1.3.3 Use lockout and tag-out when needed.

Definition of Lockout/Tagout

Lockout is a technique used to prevent equipment from being accidentally started and stored energy from being released while an associated machine or piece of equipment is being serviced. A padlock or any other appropriate mechanical device that physically prevents the transmission or release of energy is placed on the energy-isolating device that should be in the off or closed position.

Energy-isolating devices can be:

• Disconnect switches

• Circuit breakers

• Valve handles

• Blocks

• Blind flanges

A tag also will be placed together with the locking device, to explain why the equipment is locked, by whom and for how long. The use of only tags, without locks, is acceptable if additional measures to protect equipment are put in place. For example:

• Removal of the circuit-isolating element

• Removal the valve handle

• Blockage of a controlling device

The ultimate goal of lockout/tagout is to protect the safety and health of employees. Secondary is the protection of equipment from damage.

Types of Lockout Devices:

• Disconnect switches • Slide gates • Valves (ball, gate, etc.)

Colour Code for Locks and Tags:

Locks:

• Blue locks - equipment locks - used to protect equipment. • Red locks - used for Personal Protection. • Green locks - given to contractors to use on equipment.

• Orange Locks - control a group lockout. Locks out many pieces of equipment with only one locking device.

Tags:

• Red tags with Red locks - used for personal protection of employees. • Red tags with Green locks – used for contractor protection. • Yellow tags with Blue locks – used for protection of equipment. • Yellow tags without a lock – non-energized equipment out of service. The tag will tell what is wrong with the equipment.

The 5 Main Causes of Fatal Lockout/Tagout Injuries:

1. Failure to stop equipment

2. Failure to disconnect from power source

3. Failure to dissipate (bleed, neutralize) residual energy

4. Accidental restarting of equipment

5. Failure to clear work areas before restarting

Lockout Procedure:

1. Preparation for Shutdown – study the equipment and the source(s) of energy before tagging/locking it. Alert the operator (s) that power is going to be disconnected.

2. Equipment Shutdown

3. Equipment Isolation – find and isolate every form of energy that the machine uses.

4. Application of Lockout Devices – apply lock and/or tags to all energy isolating equipment. Anything that might restore the flow of energy to the work area must be locked out.

5. Control of Stored Energy – after locking out/tagging out the equipment, the stored energy must be controlled by:

i. Relieving any residual energy ii. Waiting until moving parts stop

iii. Relieving trapped pressure iv. Installing ground wires to discharge electrical capacitors v. Blocking or supporting elevated equipment

6. Verify Equipment Isolation – before starting the work, check once more if all the equipment is locked out/tagged out and free from stored energy.

Removal of Lockout

1. Restore Serviced Equipment:

• Remove all tools • Ensure all equipment components are securely in place • Re-attach all safety features (guards) • Close serviced equipment • Ensure equipment is safe to operate

2. Notify Personnel – that lockout/tagout devices are going to be removed

3. Remove lockout/tagout devices – only the person who placed each lockout/tagout device is authorized to remove them.

Reactivating Equipment

1. Wait until the last lockout/tagout device is removed

2. Gather all workers involved in the operation in a safe place, to ensure nobody is still working in the area

3. Tell workers the equipment is going to be re-energized

4. Re-energize the equipment

Follow Up:

1. Report any problems found with the lockout/tagout procedure to your supervisor

2. Share this information with workers who were involved in the operation

1.3.4 Identifyalltheorganizationthatgovernsthesafetyof hazardousmaterial.

A series of regulations have been introduced under OSHA 1994. The emphasis of these regulations has been on establishing mechanism to implement OSH in workplaces. Workplaces with five or more workers are required to formulate a Safety and Health Policy. The Safety and Health Committee Regulations 1996 requires establishments with 40 workers and above to establish a safety and health committee. The committee is required to meet at least once in every three months, with the functions to identify hazards at the workplace, institute control measures, investigate incident and conducting audit.

In terms of representation in the committee, workplace with less than 100 workers will need to have at least two representatives each for workers and management respectively. However, workplaces with more than 100 workers will need to have a minimum of four representatives each for workers and management.

The Safety and Health Officer Regulations provide for specific industries to have a Safety and Health Officer (SHO). A SHO is an individual who has attended training in National Institute of Occupational Safety and Health (NIOSH) or other accredited training bodies and has passed the examination conducted by NIOSH and registered with Department of Safety and Health (DOSH).

Accident Investigation

Purpose:

• To establish the causes of the accidents• To establish proper control measures so that future accident can be prevented• To records all facts about the accident for various reasons (compensation, claims etc.)• To analyse trend and cost for long term planning

Who Should Investigate (Under The Act)

• Supervisor • Safety and Health Officer • Safety and Health Committee Members • Special Team

Responsibilities for Safety and Health

The Occupational Safety and Health Act, 1994 (Malaysia) places a general duty of careupon managers to ensure, as far as is practicable, that their employees are not exposed tohazards. The same Act also places on employees the responsibility to ensure that they donot expose themselves or others to hazards. The University acknowledges that the ViceChancellor is ultimately accountable for the safety and health of its staff, students, visitors,contractors and persons under labour hire agreements, and is committed to providing andmaintaining a safe and healthy workplace.

Responsibilities of Managers and Supervisors

Managers and supervisors have an overall responsibility to ensure that employees are notexposed to hazards at work. The Act bestows a number of specific duties on managers.

1. Provide and maintain workplaces, equipment and systems of work that do not exposeemployees to hazards.

To achieve this, a manager needs to:• determine safe methods of work and ensure staff perform their work in a safe manner• develop and maintain safety policies and guidelines on safe work procedures• ensure that the existing working environment, equipment, processes and work practicesdo not expose staff to hazards• assess the risks associated with any intended changes to staff duties and work practicesand make practicable changes to improve safety and health in the workplace• assess items before purchase or lease to ensure staff will not be exposed to hazards• identify hazards in the work area, make assessments of risk and apply practicablecontrol measures• investigate incidents to find ways of preventing them recurring• budget for the provision and maintenance of the working environment and appropriateequipment to enable work to be carried out safely.

2. Provide information, instruction, training and supervision so employees can performtheir work safely.

To achieve this, a manager needs to:• establish and maintain information on managing the known hazards in the workarea, including:(i) policies and safe work procedures(ii) Malaysian Standards, Codes of Practice and Guidance Notes(iii) Material Safety Data Sheets (MSDS) on hazardous substances• make sure staff are familiar with appropriate safety policies, guidelines, standards,codes of practice and MSDSs that relate to their work• provide relevant training to staff on safety and health in the workplace• maintain records of what training has been provided, when and to whom• ensure staff are supported and supervised in performing their work safely• promote safe work practices and safety and health in the workplace.

3. Consult and cooperate with employees and Safety and Health Representatives(SHRs).

To achieve this, a manager needs to:• know and support the SHR for their work area• consult employees and SHRs about proposed changes to the working environment.• make decisions about how to resolve safety and health issues following consultation• inform the SHR of identified hazards and incidents in their work area

• work with the SHR to identify and investigate hazards and incidents and developappropriate control measures.

4. Provide adequate protective clothing and equipment where hazards cannot be avoided.

To achieve this, a manager needs to:• know what protective clothing and equipment is required for the hazards in theirwork area• make sure the appropriate protective clothing and equipment is available, and thereare facilities for cleaning, maintenance and storage• provide instruction and training on how to use and maintain the protective clothingand equipment correctly• ensure that employees, students and visitors under their control correctly use protectiveclothing and equipment provided.

Introduction

Hand Tools - Tools that are manually operated and powered by human force such as screw drivers, pliers, wrenches, and cutting shears, etc.

Portable Power Tools - Power tools that are hand held, manually operated, and powered by electricity, air, gasoline, diesel, or explosion, such as circular saws, sanders, drills, reciprocating saws, air wrenches, air grinders, air fasteners, chainsaws, “Ramset guns” etc.

Different types of power tools source:

Electric

Pneumatic

Liquid fuel

Hydraulic

Powder-actuated

Each employer shall be responsible for the safe condition of tools and equipment used by employees, including tools and equipment which may be furnished by employees. Employers shall not issue or permit the use of unsafe hand tools. Wrenches, including adjustable, pipe, end, and socket wrenches shall not be used when jaws are sprung to the point that slippage occurs. Impact tools, such as drift pins, wedges, and chisels, shall be kept free of mushroomed heads. The wooden handles of tools shall be kept free of splinters or cracks and shall be kept tight in the tool.

Employees who use hand and power tools and who are exposed to the hazards of falling, flying, abrasive and splashing objects, or exposed to harmful dusts, fumes, mists, vapors, or gases must

be provided with the particular personal equipment necessary to protect them from the hazard. Employees and employers have a responsibility to work together to establish safe working procedures. If a hazardous situation is encountered, it should be brought to the attention of the proper individual immediately.

Appropriate personal protective equipment should be worn due to hazards that may be encountered while using portable power tools and hand tools.

Floors should be kept as clean and dry as possible to prevent accidental slips with or around dangerous hand tools.

1.4 Identifytypesofhand tools,powertoolsandmaintenanceequipments.

General Hazards:

• The two most common hazards associated with the use of hand tools are misuse and improper maintenance. • Misuse occurs when a hand tool is used for something other than its intended purpose. (An example would be using a screwdriver as a chisel. This may cause the tip to break and strike someone). • Improper maintenance allows hand tools to deteriorate into an unsafe condition. (Examples would include cracked wooden handles that allow the tool head to fly off or mushroomed heads that can shatter upon impact).• Specially designed tools may be needed in hazardous environments. (Always use non-sparking tools in the presence of flammable vapors or dusts. Insulated tools with appropriate ratings must be used for electrical work).

Personal Protective Equipment:

• The type of personal protective equipment (PPE) needed when using hand tools depends on the nature of the task. At a minimum, eye protection should always be worn.• The use of hand protection may also be appropriate to provide protection against cuts, abrasion, and repeated impact.

1.4.1 Listthe mostcommon typesofhand tool andpowertools.Wrenches:

• Choose a wrench that properly fits the fastener that is to be turned. Using the correct size reduces the chances of wrench slippage. • Avoid using a length of pipe or other extension to improve the leverage of a wrench. Manufacturers design wrenches so that the amount of leverage obtained with the handle is the maximum safe application. • Use socket wrenches for hard-to-reach areas. • Always try to pull on a wrench (instead of pushing) in case the fastener suddenly loosens. • Inspect wrenches periodically for damage such as cracking, severe wear, or distortion.

Pliers:

• Do not increase the handle length of pliers to gain more leverage. Use a larger pair of pliers or bolt cutters.• Do not substitute pliers for a wrench when turning nuts and bolts. Pliers cannot grip these items properly and will slip.• Never use pliers as a hammer or hammer on the handles. Such abuse is likely to result in cracks or breaks.• Cut hardened wire only with pliers designed for that purpose.• Always cut at right angles. Never rock from side to side or bend the wire back and forth against the cutting edges.

Hammers:

• Do not use a hammer if the handle is damaged or loose.• Never weld, heat, or regrind a hammer head.• Remove from service any hammer exhibiting signs of excessive wear such as cracks, chips, or a mushroomed head.• Match the proper type of hammer to the job it is designed to perform.• Do not strike the surface at an angle. The hammer face should contact the striking surface squarely. Glancing blows made with a hammer often lead to injury.

Screwdrivers:

• Never use a screwdriver as a pry bar, chisel, punch, stirrer, or scraper. • Always use a screwdriver tip that properly fits the slot of the screw. • Throw away screwdrivers with broken or worn handles. • Use magnetic or screw-holding screwdrivers to start fasteners in tight areas. • Never use pliers on a screwdriver for extra leverage. Only use a wrench on screw drivers specifically designed to accept them.

Utility Knives/Blades:

• Always use a sharp blade. Dull blades require more force and thus are more likely to slip. Replace the blade when it starts to “tear” instead of cut.• Never leave a knife unattended with the blade exposed. Consider using a selfretracting knife with a spring-loaded blade. (The blade will retract when pressure on the knife is released).• Keep your free hand away from the line of the cut.• Don’t bend or apply side loads to blades by using them to open cans or pry loose objects. Blades are brittle and can snap easily.

1.4.2 Demonstratetheproperuseofvarious typesofhandtooland powertools.1.4.3 Determine theimportanceofinspectingahand toolandpower

tools

Today’s Power Tools

Offer more power, adaptability and dependability than ever before.With enhanced tool performance comes the responsibility to address power-tool safety issues. Maintenance management professionals and technicians responsible for specifying and using power tools have a responsibility to check out a tool's safety features, then ensure that manufacturer safety precautions and common sense are followed at all times.

Hazards of Power Tools

All hazards involved in the use of power tools can be prevented by following five basic safety rules:

i. Keep all tools in good condition with regular maintenance. ii. Use the right tool for the job.

iii. Examine each tool for damage before use. iv. Operate according to the manufacturer's instructions. v. Provide and use the proper protective equipment.

vi. General Safety Guidelines for Power Tools The following information offers general safety guidelines for power tools

Individual manufacturers' tool owner/operator manuals, shipped with tools and accessories, are recommended as a final source for proper procedures for specific tool use.

General Safety Guidelines for Power Tools

i. Know the power tool. ii. Operators must read and understand the owner's manual.

iii. Labels affixed or included in the shipping container must be read and understood. iv. Ground all tools unless double insulated. v. Avoid dangerous environments. Do not use power tools in a damp, wet and/or explosive

atmosphere -- fumes, dust or flammable materials. General Safety Guidelines for Power Tools

i. Be aware of all power lines and electrical circuits, water pipes, and other mechanical hazards in your work area, particularly those below the work surface, hidden from the operator's view, that may be contacted.

ii. Wear proper apparel. Do not wear loose clothing, dangling objects or jewelry. Long hair must be restrained. Gloves should not be worn when operating certain power tools. Check appropriate tool manuals.

General Safety Guidelines for Power Tools

i. Power tools can be hazardous when improperly used. ii. Employees should be trained in the use of all tools - not just power tools. They should

understand the potential hazards as well as the safety precautions to prevent those hazards from occurring.

General Safety Guidelines for Power Tools

i. The following general precautions should be observed by power tool users:ii. Never carry a tool by the cord or hose.

iii. Never yank the cord or the hose to disconnect it from the receptacle. iv. Keep cords and hoses away from heat, oil, and sharp edges. v. Disconnect tools when not in use, before servicing, and when changing accessories such

as blades, bits and cutters. General Safety Guidelines for Power Tools

i. All observers should be kept at a safe distance away from the work area. ii. Secure work with clamps or a vise, freeing both hands to operate the tool.

iii. Avoid accidental starting. Workers should not hold a finger on the switch button while carrying a plugged-in tool.

General Safety Guidelines for Power Tools

i. Tools should be maintained with care. They should be kept sharp and clean for the best performance. Follow instructions in the user's manual for lubricating and changing accessories.

ii. Be sure to keep good footing and maintain good balance. iii. The proper apparel should be worn. Loose clothing, ties, or jewelry can become caught in

moving parts. iv. All portable electric tools that are damaged shall be removed from use and tagged "Do

Not Use."

2IzharBin Ahmad (PTSB)FadzliHaizamBin Hamzah (PSP)

1 Explain lubrication principle.

GENERAL

This section provides an overview of the fundamentals of lubrication. Included are the basic properties and functions of a lubricant, and how a lubricant acts to reduce friction and wear, dissipate heat, and prevent corrosion.

INTRODUCTION

The three major types of lubricants in use in industrial are LUBRICATING OILS, GREASES, and SOLID LUBRICANTS. The selection of a lubricant type is dependent on the type of machinery to be lubricated, the complexity of the lubricating system allowed by machinery design, and the frequency of lubrication required.

Learning OutcomesUpon completion of this chapter, students should be able to:-

1. Understandlubrication principle.2. Understandfluidmanagement.3. Identifylubricatingdevicesandsystem.4. Determinelubricatingprogram

LUBRICATING OILS

Lubricating oils are used for the majority of applications. They may be classified according to their viscosities and any special properties imparted to them by additives. Oils whose base stocks are derived primarily from crude oil refining are called mineral or petroleum oils. Petroleum oils may be further classified as being paraffinic or naphthenic based on the types of hydrocarbons comprising the base stock. Oils that have been manufactured by chemical synthesis such as polymerization are called synthetic oils. Additives may be blended into the base stock to impart special properties to the finished product. A list of commonly used lubricant additives is provided in Table 2.1

GREASES

Greases are typically used in situations where sufficient lube oil cannot be effectively maintained on machinery surfaces, or when a simplistic lubricating system is desired or required. Greases essentially consist of a semisolid mixture of oil and thickening agent. The oil may be either petroleum or synthetic base. Thickening agents are typically alkali soaps or clay (bentonite) materials. Critical grease properties, such as hardness and water washout, are dependent on the selection of base oil and thickening agent. For example, sodium-soap greases exhibit poor water resistance; lithium-soap greases have good water resistance and are excellent general purpose lubricants.

Grease Application

Grease may be applied through grease cups or through hydraulic lubrication fittings. Hydraulic lubrication fittings form a readily installed and convenient means for lubricating numerous low-speeds, lightly loaded, or widely separated bearings. These fittings are not acceptable for use on electric motors or generators because of the danger of grease being forced out of the bearing and onto windings (refer to NSTM Chapter 310, Electric Power Generators and Conversion Equipment, for further discussion). A grease gun or other pressure device shall be used for applying grease through hydraulic type fittings. When grease is applied through hydraulic lubrication fittings, pressure should be applied until grease seeps out around the edges of the bearings. In bearings fitted with felt or other seals, care shall be exercised to avoid breaking the seals by the application of too much pressure. If not, the bearing will fail due to a lack of lubrication. The type of fitting should be identified and carbon steel fittings which are corroded should be replaced with Corrosion Resistant Steel (CRES) or Monel fittings.

SOLID LUBRICANTS

Solid lubricants are typically used in situations where unusual temperature or environmental conditions preclude the use of conventional fluid lubricants, or when the application of a fluid lubricant is difficult. Solid lubricants form an essentially dry lubricating film between adjacent surfaces. The lubricant may be applied directly in powdered form, or as a colloidal suspension in a vehicle such as isopropanol. Evaporation of the vehicle leaves a thin film of the lubricant on machinery surfaces. The two most commonly used solid lubricants are powdered graphite and molybdenum disulfide (MoS2). Other materials such as powdered zinc dust and red lead suspended in petrolatum or mineral oil may also be used. Specific solid lubricant applications are as follows:

Dry Graphite conforming to ss-G-659

May be used for the lubrication of such equipment as security locks. Powdered molybdenum disulfide conforming to MIL-L-7866 is used primarily as a thread anti seize compound. For the lubrication of threaded steel nuts and bolts, including superheated steam components up to 565°C (1050°F), high temperature antiseize compound conforming to MIL-A-907 is typically used. This lubricant consists of a mixture of graphite and molybdenum disulfide suspended in mineral oil. For threaded aluminum parts engaged with similar or dissimilar metals, zinc dust-petrolatum anti seize compound MIL-T-22361 shall be used. Additional lubricants for use on threaded fasteners include colloidal graphite in isopropanol (MIL-L- 24131) and molybdenum disulfide in isopropanol (MIL-L-24478).

FRICTION AND WEAR

The surfaces of machinery components appear well-finished to the naked eye. When magnified, however, surface imperfections become readily apparent. These microscopic hills and valleys are called asperities. When dry surfaces move relative to one another, asperities may rub, lock together, and break apart. The resistance generated when these adjacent surfaces come in contact is called friction. The welding together and breaking apart of asperities is a form of adhesive wear. Another form of wear may occur when a hard contaminant particle becomes trapped between two opposing surfaces. When this occurs, the contaminant acts as a miniature lathe, cutting into the softer machinery surface. This process is termed abrasive wear. Another consequence of friction is that the energy created by resistance is converted into heat. The primary functions of a lubricant, then, are the formation of a protective film between adjacent surfaces to reduce wear, and the dissipation of heat generated at these wear surfaces.

CORROSION PROTECTION

A second role provided by a lubricant is the prevention of system corrosion. In environments where contamination of the system with water is likely, protection of machinery components from corrosion is of the utmost importance. Salt water is considerably more corrosive than fresh water. Water molecules may also diffuse through the lubricant and enter surface micro cracks, causing hydrogen embrittlement and subsequent surface failure. It is thus imperative that water contamination of machinery systems be minimized. To achieve corrosion protection, lubricants must form a protective barrier on machinery surfaces. Modern day lubricants often contain corrosion inhibitors which chemically bond to the metallic surfaces of equipment components. Corrosion inhibitors are an example of a class of compounds called additives.

2.1.1 Describe lubrication system and benefit implement lubrication system. An organized lubrication program should be an important component of preventive maintenance. Machinery is costly, and newer models designed for greater precision and faster production certainly require proper lubrication. An organized lubrication program will reduce the possibility of breakdowns and save on repairs, downtime, and lost production. Successful lubrication programs involve both management and plant personnel.

2.1.2 State several term and principle to understand and select proper lubrication.

There are ten (10) terms and principals as stated below:

a) Viscosityb) Cloud point and pour pointc) Flash point and fire pointd) Neutralization numbere) Total base numberf) Water contentg) Demulsibilityh) Hardnessi) Water washoutj) Load carrying ability

a) Viscosity.The most important physical property of a lubricant is its viscosity. Viscosity, which may be defined as a fluid’s resistance to flow, is the characteristic most frequently stipulated by equipment manufacturers when making lubricant recommendations. The selection of proper lubricant viscosity is often a compromise between selecting one high enough to prevent metal to metal (wear) contact, and one low enough to allow sufficient heat dissipation. In the past, viscosity was measured in such units as Saybolt Universal Seconds (SUS),Redwood No. 1 Seconds, and Engler Degrees. The preferred unit of measurement for the U.S. Navy is the centistokes (cSt). Kinematic viscosity in centistokes is obtained by measuring the time required for a specified volume of fluid to flow through a calibrated capillary tube at a specified temperature. Various industry standards exist for the characterization of lubricant viscosity. The most familiar of these is the Society of Automotive Engineers (S.A.E.) classification of automotive engine and gear case oils. (Table 2.2) This system grades lubricants according to their viscosity characteristics at either -18°C (0°F) or 100°C (212°F). Oils meeting low temperature viscosity requirements are assigned a Wafter the grade number (for example, SAE grade 10W). Oils meeting high temperature requirements are assigned a grade number such as SAE grade 30. Multi grade oils may be formulated to meet both low and high temperature requirements (for example, SAE grade 10W-30). However, these viscosity designations are applicable primarily for the lubrication of internal combustion engines. By international agreement, all nations now recognize a universally applicable system of viscosity classification termed the International Standards Organization (ISO)/American Society of Testing and Materials (ASTM) Viscosity System for Industrial Lubricants. This system assigns viscosity grades from ISO VG2 through VG1500, where the number indicates the midpoint viscosity in centistokes of the lubricant at 40°C (104°F).

Table 2.1

b) Viscosity Index

The effect of temperature on a lubricant’s viscosity is a measurement of its Viscosity Index (VI). When the VI scale was introduced in 1929, a reference paraffinic base stock was assigned a VI of 100, and a naphthenic base stock a VI of 0. Most naval oils of paraffinic base stock have VI’s in the 95-100 range. Naval oils prepared from synthetic stock, and multi grade engine oils typically have VI’s in excess of 100. (Synthetic and paraffinic stocks are discussed further in detail in paragraph (Table 2.3). The higher the VI, the less a given lubricant’s viscosity will change with a subsequent change in temperature.

c) Cloud Point and Pour Point

Table 2.3

Since petroleum stock consists of a mixture of molecular components, lubricants do not exhibit sharp freezing points. Rather, as a lubricant is cooled, certain components such as waxes will begin to precipitate out and become evident in the liquid as a cloud. The temperature at which this occurs is called the cloud point of the lubricant. If the product is further cooled, a point will be reached at which the lubricant will no longer flow or be efficiently pumped. The temperature at which this occurs is termed the pour point of the lubricant. Both properties are related to the wax content of the base stock. The pour points of high-wax lubricants may be depressed by the addition of pour point depressant additives. Pour point behavior becomes important in applications such as refrigerant compressor lubrication where the oil is subjected to low temperatures.

d) Flash Point and Fire Point

As a lubricant is heated, lighter components begin to vaporize.The temperature at which sufficient vapor concentration exists above the surface of the lubricant so that ignition with a test flame is possible is called the flash point of the product. Flash point is useful for both product storage requirements and for the detection of contamination of one product with another. The fire point of a lubricant is that temperature at which sufficient vapors are present above the surface of the lubricant to sustain combustion upon ignition. This parameter is useful for storage and safety considerations.

e) Neutralization Number

As petroleum products are subjected to elevated temperatures, the process of oxidation occurs. Oxidation leads to the formation of organic acids in the lubricant. This increase in acidity reduces the water-separating ability of certain oils, and may also prove corrosive to certain alloys. The neutralization number measures the amount of acidity present in the lubricant. It is quantitatively defined as the amount of potassium hydroxide (KOH) required neutralizing the acid present in one gram of sample. This quantity is also referred to as the Total Acid Number (TAN).

f) Total Base Number

Internal combustion engine oils are formulated with a highly alkaline (base) additive package designed to neutralize the acidic byproducts of combustion. The Total Base Number (TBN) is a measure of this additive package, and it may be used as an indication of when diesel engine oil should be changed.

g) Water Content

The most common contaminant in Naval lubricating systems is water. Common sources of water include lube oil cooler leaks, condensation, steam turbine gland seal leaks, and diesel engine piston blow-by and jacket water leaks. The acceleration of system corrosion by water contamination cannot be overemphasized. In addition, excessive water contamination increases the viscosity and decreases the fluid film strength of oil. This may result in accelerated wear due to rupture of the oil film and resultant surface to surface contact. A qualitative assessment of the amount of water present in some lubricants may be made by inspecting the oils’ appearance. Another method for determining water contamination levels is the Bottom Sediment & Water (B.S.& W.) test.

h) Demulsibility

Demulsibility refers to a lubricant’s ability to readily separate from water. Oils used in force-feed lubrication systems should possess good water reparability to prevent emulsification.

i) Hardness

Greases are classified according to a hardness scale developed by the National Lubricating Grease Institute (NLGI). According to this system, softer greases are assigned a low NLGI number, and stiffer greases a high NLGI number (see Table 2.4). The penetration numbers refer to the depth, in tenths of millimeters, that a weighted cone penetrates the grease. Most Naval greases have NLGI numbers from 1 to 2, and are classified as medium consistency greases.

j) Dropping Point

Greases exist in an essentially semi-solid form. The temperature at which grease changes from a semi-solid to a liquid is termed its dropping point. Dropping point provides some indication of the high temperature characteristics of grease.

k) Water Washout

Greases subjected to splashing or impinging water must possess good water washout resistance. Greases with good resistance will maintain an adequate lubricating film under excessive water contamination conditions.

l) Load Carrying Ability

The ability of a lubricant to maintain an effective lubricating film under high loads or pressures is a measure of its load carrying or extreme pressure (EP) characteristics. The load carrying ability of a lubricant may be enhanced by the addition of EP additives (see Table 2.1).

2.2 Distinguish fluid management.

2.2.1 Apply four essential components in a fluid management program.

In lubrication there five (5) essential components as stated below:

a) Selection and purchase of lubrication.b) Lubrication monitoring during use.c) Lubricant maintenance using processing. d) Refortification techniques.e) Disposal of the spent lubricant.

a) Selection and purchase of lubrication Fluid management begins with purchasing the correct lubricant for the application. For most equipment, premium long-lasting lubricants meeting equipment manufacturers’ recommendations and specifications should be purchased. During the competitive bidding process, purchasing personnel should carefully consider the supplier, products, and services. A supplier should be chosen on the basis of the quality of lubricants and services (engineering lubrication surveys, troubleshooting, used oil analyses, etc.) offered rather than on price alone. The overall cost of lubrication compared with the total cost of plant equipment is relatively insignificant. Purchase of

Table 2.4

lubricants on the basis of price alone is not justified when considering the cost of downtime for repair and lost productivity if attributed to the use of an inferior lubricant. On the other hand, purchase of premium-grade lubricants will not improve or correct lubrication problems if mechanical factors such as misalignment or severe environments (high levels of dirt and water contaminants) are involved.

b) Lubrication monitoring during use Monitoring programs may be used to determine the condition of the lubricant and to detect early signs of equipment failure. Used oil analyses also can be used to extend lubricant life and establish oil change out intervals. The properties that should be monitored are dependent on the application and environment. Table 1.2 lists the properties and condemning limits for most large-volume applications of industrial lubricants, namely, turbine/circulating, hydraulic, compressors, and gear oils. Other lubricant applications, such as slide ways, rock drills, etc., which involve small volumes and/or once through applications, need no monitoring. The results of monitoring tests can be used in some cases to correct conditions that are contributing to degradation of the lubricant. For example, if the lubricant in a circulating system shows that water is present, it may be possible to locate and eliminate the source of the water. If the viscosity is dropping, it may be determined that incorrect oil is being used for makeup, or there may be leakage of a different lubricant into the system. The condemning limits shown in the table are intended to serve as general guidelines. The lubricant supplier should provide actual limits for the products being used and interpretation of used oil test results.

c) Lubricant maintenance using processing Lubricant maintenance is closely associated with the monitoring program. When used oil test results exceed the condemning limits, corrective action needs to be taken. Such action could include filtration to remove particulate matter and in some cases oxidation products and/or dehydration. This processing can be done either on site or at a recycle station. Additive replenishment for depleted inhibitors may be feasible for some products in some applications. Since additive replenishment requires a considerable amount of technical expertise, the lubricant supplier should be contacted to provide information and service to reclaim and refortify used lubricants.

d) Refortification techniques Lubricant maintenance is closely associated with the monitoring program. When used oil test results exceed the condemning limits, corrective action needs to be taken. Such action could include filtration to remove particulate matter and in some cases oxidation products and/or dehydration. This processing can be done either on site or at a recycle station. Additive

replenishment for depleted inhibitors may be feasible for some products in some applications. Since additive replenishment requires a considerable amount of technical expertise, the lubricant supplier should be contacted to provide information and service to reclaim and refortify used lubricants.

e) Disposal of the spent lubricant.

Disposal is the last step that must be addressed in fluid management when the monitoring results indicate that the oil is severely degraded and/or depleted of additives that cannot be restored. Various options to consider include recycling, burning, land-filling, and re-refining. The most appropriate method of disposal will depend on local, state, and federal regulations. These will clearly be affected by the location, which makes the best method of disposal site-specific. Lubricant disposal needs to be considered carefully on a case-by-case basis.

2.3 Understand lubrication protection.

Proper handling and storage of lubricants and greases are important to ensure longevity and satisfactory performance. Premium-grade products should be stored inside to prevent contamination with dirt and water and to protect against temperature extremes. If drums are stored outside, they should be stored on their sides, tilted, or upside down. Drums will expand and contract as the temperature changes and any water on top of a drum may be drawn through the bung as the drum expands and contracts. Ester- and polyglycol-based lubricants need especially to be protected from atmospheric humidity.

2.3.1 Organize lubrication protection in term of:

a) Location and personalb) Facilities for handling containerc) Lightingd) Bulk storagee) Fire protection

a) Location and Personnel

A clean, well-lighted room or building is advisable, with provisions for heating in cold weather. It should be specifically kept for lubricant storage and reserve lubricating equipment. In most plants, one or two individuals are assigned the responsibility for inventory and dispensing of lubricants. These individuals should be trained on the importance of protecting lubricants from contamination and commingling with other lubricants. Drums should be labeled clearly to ensure application/use of the correct lubricant.

b) Facilities for Handling Containers

One-level handling is an important item wherever possible in planning for lubricant storage. If practical, the floor level should be the same as the delivery-truck floor. This facilitates rolling of drums into the storeroom, where racks can be arranged along one or more walls so that oil drums can be raised by a forklift truck and spotted in order to draw the contents off with the least effort into distribution containers. Each drum should have its own spigot to avoid commingling of products. Grease drums are normally stored on end because the contents are removed by paddle, scoop, or pressure pump, according to the consistency of the grease. Paddles, scoops, and other devices must be kept clean to protect against abrasive particles and dirt. In large plants, where a considerable volume of lubricants must be stored, a set of parallel rails (see Fig. 2.1) is useful for handling full drums to service racks as well as empties for return.

FIGURE 2.1

c) Lighting

This relates to good records. The lubrication and maintenance departments can function most effectively when they have complete records as to lubricant consumption per machine per area. This requires careful inventory (monthly) and recording of amounts of oil and grease issued. Lighting plays an important part. If the storeroom is painted gloss white, if light outlets are well located to obviate glare, and if a comfortable record desk is installed, personnel will keep more careful records.

d) Bulk StorageBulk storage can be an investment that provides benefits in improved efficiency, reduced handling costs, reduced risk of contamination, and simplified inventory. Each product requires its own dedicated bulk storage system, including tank, pump, and receiving line. The tank should be equipped with a water draw-off line, sampling line, and entry to permit periodic tank cleaning. If tanks are equipped with electric heating coils or steam lines, precautions must be taken to prevent overheating and thermal degradation of the lubricant. Bulk shipments may be supplied in tank cars, tank trucks, or tote bins. Upon arrival of bulk shipments, each product should be inspected visually for clarity and cleanliness and checked for viscosity with a handheld viscometer. Prior to unloading, each tank should

be gauged to ensure sufficient room. Tank lines and valves should be checked to ensure that the product is being unloaded into the correct tank. If dedicated lines and pumps are not being used, the system should be flushed with one to three times the volume of the lines to prevent cross-contamination of products. Samples should be obtained from the tank after unloading and labeled with product name, date, invoice number, and batch number. The samples should be stored for at least 6 months.

e) Fire ProtectionThe possibility of fire in a well-planned lubricant storage area is remote, assuming that no-smoking rules are observed, that casual visits from other plant personnel are prohibited, that oil drip is prevented or cleaned up promptly, that waste or wiping rags are stored in metal containers and in minimum quantity, and that sparking or arcing tools are used only under conditions of good ventilation. Even so, insurance regulations will require installation of suitable fire-extinguishing equipment and possibly a sprinkler system. The accepted foam-type device for smothering is best. In a small storeroom, one or two hand units may suffice. In a larger area, a multiple-gallon foam cart with adequate hose may be required.

2.3 Identify lubricating devices and system.

LUBRICANT SELECTION

When choosing a lubricant for a particular piece of equipment, the equipment manufacturer’s operation and maintenance manual should be consulted. The operation and maintenance manual will usually outline the required characteristics of the lubricants as well as a recommended schedule for replacement or filtering. If the maintenance manual is not available, or is vague in its recommendations, lubricant manufacturers and distributors are other sources of information. All the pertinent information on the equipment, such as operating speed, frequency of operation, operating temperature, and any other special or unusual conditions, should be provided to the lubricant manufacturer or distributor so that a lubricant with the proper characteristics can be chosen. Some discretion should be used when dealing with a lubricant salesperson to prevent purchasing an expensive lubricant with capabilities in excess of what is required.

Whenever possible, lubricants should be purchased that can be used in several applications. By limiting the number of lubricants onsite, the chance of mixing different lubricants or using the wrong lubricant is minimized.

LUBRICANT STANDARDS

There are a number of tests and standards that have been developed to define and measure the properties of lubricants. Most of these tests have been standardized by ASTM. The properties determined by these tests can be very helpful in comparing relative performance of several lubricants, but it should be noted that many of these tests have little correlation to actual service conditions. When selecting a lubricant, the test procedures for the required properties should be reviewed so that the relevance of the test is kept in perspective.

2.3.2 Choose suitable lubricating devices system based on equipment or mechanical components.

CHARACTERISTICS OF LUBRICATING METHODS To evaluate a particular method for a specific application, certain characteristics should be considered. Following evaluation criteria can serve as a checklist to aid in selection of lubricating devices.

CATEGORIES OF LUBRICATION METHODS The methods for lubricating machine elements can be divided into following categories:

A. Manual Devices B. Drop-feed Devices C. Splash or bath lubrication D. Ring, chain, collar oilers E. Pad - and waste-type devices F. Positive force feed lubricators G. Air oil devices H. Pressure circulating systems I. Centralized lubricating systems J. Built-in-lubrication

A. Manual Devices Lubricating methods may require human action in one form or another. The term manual lubrication applies to methods in which the operator is directly responsible for quantity of lubricant and interval of lubrication. Although the initial cost of manual lubrication is low, the maintenance costs can be high. Reliability may be owing to considerable dependence on human action. The lubricant is quite prone in contamination. Generally speaking, manual lubrication is satisfactory only for lightly loaded or low speed bearings, typical applications include open gears, chains, wire rope, etc.

B. Drop-feed DevicesDrop feed devices are gravity-flow lubricators. They are employed to deliver lubricant drop-by-drop to individual bearings and other machine elements. They give the best advantage when lubricant points are readily accessible. Their cost is relatively low. Maintenance cost depends on type of service and location

depending on the lubricator, lubricant flow may or may not be stopped and started automatically. Automatic operation increase reliability. Typical service applications include journal and roller bearings, gears, chains, engine guides, pumps and compressors.

C. Splash or Bath Lubrication This type of lubrication is commonly used for machinery having high speed moving parts. These dip into oil and splash it on to the bearings or other machine elements. The splash system requires enclosing the mechanism to be lubricated. Initial cost of splash system depends on the expense incurred in enclosing the mechanism. Maintenance costs are low. A splash system is reliable, prevents contamination. Typical applications include internal-combustion engines, chain drives and enclosed gear sets.

D. Ring, Chain, Oilers These lubricators are applicable to horizontal rotating shafts. The ring or chain oiler encircles the shaft and turns freely on it. Each provides an automatic oiling system by bringing oil to the bearing clearance from the oil reservoir. Initial cost depends on housing for the bearing that must be built to contain these lubricators. Maintenance cost is usually low. Typical applications include electric motors, fans, blowers, compressors, and line shaft bearings.

E. Pad-and Waste-type Devices These lubricators use the oil-retaining properties of felt pads and waste packing to provide the lubricant to a bearing. Oil is lifted from the reservoir by capillary action in the wicking material. This system requires an appropriate housing, which accounts for a large initial cost. Maintenance cost generally depends on the environment in which they are used. They are generally low. This is often used for rail, road and traction motor bearings

F. Positive Force feed LubricatorsIt consists of one or more plunger-type adjustable-stroke pumps mounted on a common reservoir. The pumps are driven from a rotating shaft through a mechanical linkage. It may have a separate drive motor. Initial cost is high, but maintenance cost is low. The lubricant is free from contamination. Typical applications include steam cylinders, bearings for diesel and gas engines.

G. Air-oil Devices Air-oil devices operate by injecting or pumping oil drop-by-drop into an air stream. The oil is drawn by the aspiratory action of compressed air passing through an orifice or control valve. The initial-cost is very high. However, maintenance costs are low and efficiency of the devices is high. These are well suited for high speed bearings, enclosed gears, slides and table ways.

H. Pressure Circulating Systems: Pressure circulating systems employ either gravity or pumps to develop the operating pressures necessary. Generally these are designed to lubricate a number of parts on the machine. Since oil is recirculated maximum economy is

possible. Pressure circulating systems are built into the machine. Therefore initial cost is high. Maintenance costs are very low. Typical applications include steam-turbine bearings, reduction gears, steel-mill gear drives, mill bearings, paper-machine bearings and gears and internal-combustion engines.

I. Centralized Lubrication SystemsCentralized Systems can be designed for oil or grease. A typical centralized system requires centrally located reservoir and pump, and permanently installed piping and distribution valves. These deliver measures quantities of lubricant at desired points. It can be either operated manually or automatically. The piping and intricate dispensing valves make initial cost very high, but maintenance costs are very low. Initial cost is offset by dependability, durability, safety and resistance of system to contamination. Centralized Systems are ideally suited for steel and paper mills, machine tools etc.

J. Built-in-Lubrication

Built-in lubrication refers to materials or components that do not require any external lubricating device. Materials such as oil saturated porous metals, graphite materials, PTFE, nylon can rub together without a lubricant. These materials may be used for sleeve bearings, gears etc. components have built-in lubrication are well suited for use in inaccessible locations. They can reduce maintenance costs, but should not be used indiscriminately. The various categories of lubrication systems have been very briefly discussed in the above paragraphs. There are, however, very many varieties in each finding specific applications. Depending upon the severity of the working situation of machine elements the most suitable means from cost, maintenance and efficiency point of view should be selected.

2.4 Determine lubricating program.

a. The plant lubrication survey.b. Establishment of lubrication schedules and improvements in

selection and application of lubrication.c. Lubrication analysis

2.4 Determine lubricating program.

a. The plant lubrication survey.

A workable lubrication schedule should be developed, after the job of a lubricant is defined. How much, where and when? Time and effort is required to adequately cover all areas of the equipment to determine lubrication needs. A physical survey is the only way to establish a complete schedule for an lubrication points on each machine. Check the OEM (Original Equipment

Manufacturer) manual for lubrication requirements such as type and frequency of service, number of lubrication points and recommended lubricant.

b. Lubrication schedules establishment and improvements in selection and application of lubrication.

The activities to achieve and carry out an effective lubrication program are outlined in this segment and they consist of:1. The plant lubrication survey2. Establishment of lubrication schedules3. Improvement in the selection4. Applications of lubricants5. Lubricant analysis6. Fluids management7. Quality assurance,

All above activities required to implement the programs, and factors to consider if a single supplier source is desired for all plant lubricants.The program implement or should work closely with plant personnel to determine information now available and programs and procedures presently being used.

The Plant Lubrication Survey1. Identify equipment and component parts requiring lubrication, the specific

location of each machine, and the model, serial number, function, manufacturer, operating instructions, and limitations.

2. Obtain similar information for each subcomponent of the machine, such as drive motors, gears, couplings, and bearings.

3. Examine the lubricant recommendations made by the machine or parts manufacturer and supporting documentation for these selections.

4. Determine the lubricants currently used, including quantity, cost, and supply source.

5. List the schedules in effect for each lubrication point, including frequency, quantity applied, and sampling schedules. Provide similar information for all machine components.

6. Identify the nature of each lubrication point and whether circulating systems are fed from central storage tanks, individual machine sumps, or grease fittings and whether manual, semiautomatic, or automatic equipment is now being used. Operating characteristics, condition, and effectiveness of the lubrication systems encountered should be determined.

7. Make a detailed visual inspection of each machine and its components for indications of problems, such as leakage; excessive noise; high temperature; vibration; and loose, damaged, or missing parts.

8. Record information relating to the adequacy of the machine to perform its intended functions.Note: An effective approach for conducting the initial lubrication survey is to start with the units of equipment that are critical to maintaining continuous production

and work toward the less critical units. This approach will achieve the greatest results in the shortest time period. When surveying an individual machine, start at the power source and follow through each power train, identifying couplings, reducers, bearings, and wear surfaces.

Establishment of Lubrication Schedules and Improvements in Selection and Application of Lubricants

1. Review current lubrication schedules, including type and amount of lubricant used and frequency of application.

2. Determine if it is the best lubricant for the specific application commensurate with the proposed lubricant product reduction program and improved performance requirements.

3. Analyze each piece of equipment to determine if the present lubrication system is adequate and if the lubrication points or central reservoirs are readily accessible.

4. Investigate opportunities to replace inadequate systems, manual systems, and malfunctioning automatic systems with state-of-the-art automatic systems that can be justified through reduced labor, increased equipment reliability, and/or reduced energy costs.

5. Analyze operating records such as frequency of scheduled and unscheduled downtime and reason for each shutdown when preparing the new lubrication schedule.

6. Establish lubrication schedules and routings to minimize travel time and interference with production operations. Determine time required to perform specific lubrication functions and number of workers required to perform the job.

7. Establish a check-off or feedback procedure to indicate that the scheduled lubrication was accomplished with the proper lubricant.

8. Record and report the amount and type of lubricant consumed in each area and on major pieces of equipment.

9. New equipment lubrication specifications are to be determined prior to installation of the equipment.

10. Place tags at each fill point that calls out lubricant to be used, amount of lubricant, and lubrication schedule.

Lubricant Analysis

1. Establish the objectives of the analysis program, that is, monitor and track wear and lubricant quality to detect problems caused by adhesion, friction, and corrosion before there is major component damage and to determine when lubricant should be filtered, replaced, and/or fortified with additives.

2. Select the plant equipment to be included in the analysis program. Equipment selection is usually based on the importance of the equipment to continuity of plant operations.

3. Determine the sampling frequencies for each component.

4. Design the testing packages to meet the selected objectives. Typical tests for gear reducer lubricants include :

Wear particle analysis—wear metals, contaminate metals, and additive metalsTotal solids percentage volume—contamination leaks or environmental conditionsViscosity—fluidity of the lubricantInfrared analysis—oxidation/nitration (general lube degradation)Neutralization number—reserve alkalinity (Total base number [TBN])or total acidity (Total acid number [TAN])

5. Select a lubricant testing laboratory that can accurately test the parameters chosen and report the results in a comprehensive manner on a timely basis.

6. Determine the cost of the analysis program.

7. Develop the sampling procedures and modify equipment as necessary to extract representative samples while the equipment is in operation.

8. Establish sampling, testing, and reporting schedules.9. Develop procedures and lines of communication to report results and to initiate

actions dictated by the test results.10. Establish a program review schedule.

Note: A close liaison should be maintained between the lubricant analysis program and other predictive maintenance activities.

b. Lubrication Analysis

1. Establish the objectives of the analysis program, that is, monitor and track wear and lubricant quality to detect problems caused by adhesion, friction, and corrosion before there is major component damage and to determine when lubricant should be filtered, replaced, and/or fortified with additives.

2. Select the plant equipment to be included in the analysis program. Equipment selection is usually based on the importance of the equipment to continuity of plant operations.

3. Determine the sampling frequencies for each component.4. Design the testing packages to meet the selected objectives. Typical tests for gear

reducer lubricants Include Wear particle analysis—wear metals; contaminate metals, and additive metalsTotal solids percentage volume—contamination leaks or environmental conditions Viscosity—fluidity of the lubricantInfrared analysis—oxidation/nitration (general lube degradation)Neutralization number—reserve alkalinity (Total base number [TBN]) or total acidity (Total acid number [TAN])

5. Select a lubricant testing laboratory that can accurately test the parameters chosen and report the results in a comprehensive manner on a timely basis.

6. Determine the cost of the analysis program.7. Develop the sampling procedures and modify equipment as necessary to extract

representative samples while the equipment is in operation.8. Establish sampling, testing, and reporting schedules.9. Develop procedures and lines of communication to report results and to initiate

actions dictated by the test results.10. Establish a program review schedule.

Note: A close liaison should be maintained between the lubricant analysis program andother predictive maintenance activities.

References

Asseff, P.A., Lubrication Theory and Practice, The Lubrizol Corporation.

Bloch, H.P., Practical Lubrication for Industrial Facilities, Fairmont Press, 2000

Conoco Inc., Lubrication Manual, 1981.

Ehrlich, M. (Ed), Lubricating Grease Guide, National Lubricating Grease Institute, 1st Edition, Kansas City, Missouri, 1984.

Exxon Corporation, Proving Ground, 1988.

Fein, R.S., and F.J. Villforth, Lubrication Fundamentals, LUBRICATION, vol. 59, October-December 1973.

Pirro, D.M., A.A. Wessol, Lubricant Fundamentals, 2nd Edition, Marcel Dekker, Inc., 2001.

Rein, S.W., Viscosity-I, LUBRICATION, vol. 64, No. 1, 1978.

Standard Guide for Cleaning, Flushing, and Purification of Steam, Gas and Hydroelectric Turbine Lubrication Systems, ASTM Standard No.D6439-99.

Troyer, D., and J. Fitch, Oil Analysis Basics, Noria Corporation, 2001.

U.S. Army Corps of Engineers, Lubricants and Hydraulic Fluids, Engineering Manual 1110-2-1424, 1999.

PO

Nor HishamBin Suhadi (PIS)Abdul Rashid Bin Talib (PMK)

Arman Bin Md. Said (PMM)

POWERTRANSMISSION

INTRODUCTION

Power transmission is the movement of energy from its place of generation to a location where it is applied to performing useful work.Power is defined formally as units of energy per unit time.

3.1 Describethedrivemechanismintheprocessoftransformingpower from one pointtotheother. Mechanical power may be transmitted directly using a component such as driveshaft,transmission gears, belt drives, chain drives and arm connectors.

3.1.1 Classifytypesof drivemechanismsbeltdrive, chaindrive and gear drive

i. Belt Drive

PO

Learning OutcomesUpon completion of this chapter, students should be able to:-

1. Describethedrivemechanismintheprocessoftransformingpower fromone pointtotheother.

2. Describegear in powertransmissionsystem.3. Definebeltdrives inpower transmissionsystem4. Understandchain drive.5. Implementcoupledshaftalignment orvariable-speed drives

A belt is a loop of flexible material used to link two or more rotating shafts mechanically.

ii. Chain Drive

Chain passing over a pair of sprocket, with the teeth of the sprocket meshing with the holes in the links of the chain.Drive chains are most often made of metalwell-made chains may prove stronger than belts.

iii. Gear Drive

A gear is a rotatingmachine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. The most common situation gears are meshing each other. However a gear can also mesh a non-rotating toothed parts. The gears in a transmission are analogous to the wheels in a pulley. An advantage of gears is that the teeth of a gear prevent slipping. When two

gears of unequal number of teeth are combined a mechanical advantage is produced, with both the rotational speeds and the torques of the two gears differing in a simple relationship.

3.2 Describegear in powertransmissionsystem.

3.2.1 Listapplicationofgear.

i. Transmission

Two or more gears working in tandem are called atransmission and produce a mechanical advantagethrough a gear ratio and thus may be considered a simple machine. In transmissions which offer multiple gear ratios, such as bicycles and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term is used to describe similar devices even when gear ratio is continuous rather than discrete, or when the device does not actually contain any gears, as in a continuously variable transmission.

ii. Direction

Geared devices can change the speed, magnitude, and direction of a power source.A system called a rack and pinion, when circular motion is changed into linear motion. If the pinion rotates in a fixed position and non-rotating toothed part the rack moves in a linear motion, therebyproducing translation. Adjacent gears on a gear train rotate in opposite directions. Notice that if the driver rotates clockwise then the follower rotates anticlockwise.

iii. Couplings

A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded.

The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. By careful selection, installation and maintenance of couplings, substantial savings can be made in reduced maintenance costs and downtime.

3.2.2 Classifytypes ofgearsandtheir characteristics basedonit’sfunction.

i. External vs internal gears

Internal gear

An external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, an internal gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle exceeding 90 degrees. Internal gears do not cause output shaft direction reversal.

ii. Spur

Spur gear

Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with the teeth projecting radially, and although they are not straight-sided in form, the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel shafts.

iii. Helical

Helical gears

Helical or "dry fixed" gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. Helical gears can be meshed in parallel or crossed orientations. The former refers to when the shafts are parallel to each other; this is the most common orientation. In the latter, the shafts are non-parallel, and in this configuration the gears are sometimes known as "skew gears".

The angled teeth engage more gradually than do spur gear teeth, causing them to run more smoothly and quietly. With parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheel; a moving curve of contact then grows gradually across the tooth face to a maximum then recedes until the teeth break contact at a single point on the opposite side. In spur gears, teeth suddenly meet at a line contact across their entire width causing stress and noise. Spur gears make a characteristic whine at high speeds. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is important. The speed is considered to be high when the pitch line velocity exceeds 25 m/s.

A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with additives in the lubricant.

iv. Skew gears

For a 'crossed' or 'skew' configuration, the gears must have the same pressure angle and normal pitch; however, the helix angle and handedness can be different. The relationship between the two shafts is actually defined by the helix angle(s) of the two shafts and the handedness.

The crossed configuration is less mechanically sound because there is only a point contact between the gears, whereas in the parallel configuration there is a line contact.

Quite commonly, helical gears are used with the helix angle of one having the negative of the helix angle of the other; such a pair might also be referred to as having a right-handed helix and a left-handed helix of equal angles. The two equal but opposite angles add to zero: the angle between shafts is zero – that is, the shafts are parallel. Where the sum or the difference (as described in the equations above) is not zero the shafts are crossed. For shafts crossed at right angles, the helix angles are of the same hand because they must add to 90 degrees.

v. Double helical

Double helical gears

Double helical gears, or herringbone gears, overcome the problem of axial thrust presented by "single" helical gears, by having two sets of teeth that are set in a V shape. A double helical gear can be thought of as two mirrored helical gears joined together. This arrangement cancels out the net axial thrust, since each half of the gear thrusts in the opposite direction resulting in a net axial force of zero. This arrangement can remove the need for thrust bearings. However, double helical gears are more difficult to manufacture due to their more complicated shape.

For both possible rotational directions, there exist two possible arrangements for the oppositely-oriented helical gears or gear faces. One arrangement is stable, and the other is unstable. In a stable orientation, the helical gear faces are oriented so that each axial force is directed toward the center of the gear. In an unstable orientation, both axial forces are directed away from the center of the gear. In both arrangements, the total (or net) axial force on each gear is zero when the gears are aligned correctly. If the gears become misaligned in the axial direction, the unstable arrangement will generate a net force that may lead to disassembly of the gear train, while the stable arrangement generates a net corrective force. If the direction of rotation is reversed, the direction of the axial thrusts is also reversed, so a stable configuration becomes unstable, and vice versa.

Stable double helical gears can be directly interchanged with spur gears without any need for different bearings.

vi. Bevel

Bevel Gear

A bevel gear is shaped like a right circular cone with most of its tip cut off. When two bevel gears mesh, their imaginary vertices must occupy the same point. Their shaft axes also intersect at this point, forming an arbitrary non-straight angle between the shafts. The angle between the shafts can be anything except zero or 180 degrees. Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter gears.

vii. Spiral bevels

Spiral bevel gears

The teeth of a bevel gear may be straight-cut as with spur gears, or they may be cut in a variety of other shapes. Spiral bevel gear teeth are curved along the tooth's length and set at an angle, analogously to the way helical gear teeth are set at an angle compared to spur gear teeth. Zerol bevel gears have teeth which are curved along their length, but not angled. Spiral bevel gears have the same advantages and disadvantages relative to their straight-cut cousins as helical gears do to spur gears. Straight bevel gears are generally used only at speeds below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.

viii. Hypoid

Hypoid gear

Hypoid gears resemble spiral bevel gears except the shaft axes do not intersect. The pitch surfaces appear conical but, to compensate for the offset shaft, are in fact hyperboloids of revolution. Hypoid gears are almost always designed to operate with shafts at 90 degrees. Depending on which side the shaft is offset to, relative to the angling of the teeth, contact between hypoid gear teeth may be even smoother and more gradual than with spiral bevel gear teeth. Also, the pinion can be designed with fewer teeth than a spiral bevel pinion, with the result that gear ratios of 60:1 and higher are feasible using a single set of hypoid gears. This style of gear is most commonly found driving mechanical differentials; which are normally straight cut bevel gears; in motor vehicle axles.

ix. Crown

Crown gear

Crown gears or contrate gears are a particular form of bevel gear whose teeth project at right angles to the plane of the wheel; in their orientation the teeth resemble the points on a crown. A crown gear can only mesh accurately with another bevel gear, although crown gears are

sometimes seen meshing with spur gears. A crown gear is also sometimes meshed with an escapement such as found in mechanical clocks.

x. Worm

Worm gear

4-start worm and wheel

Worm gears resemble screws. A worm gear is usually meshed with a spur gear or a helical gear, which is called the gear, wheel, or worm wheel.

Worm-and-gear sets are a simple and compact way to achieve a high torque, low speed gear ratio. For example, helical gears are normally limited to gear ratios of less than 10:1 while worm-and-gear sets vary from 10:1 to 500:1. A disadvantage is the potential for considerable sliding action, leading to low efficiency.

Worm gears can be considered a species of helical gear, but its helix angle is usually somewhat large (close to 90 degrees) and its body is usually fairly long in the axial direction; and it is these attributes which give it screw like qualities. The distinction between a worm and a helical gear is made when at least one tooth persists for a full rotation around the helix. If this occurs, it is a 'worm'; if not, it is a 'helical gear'. A worm may have as few as one tooth. If that tooth persists for several turns around the helix, the worm will appear, superficially, to have more than one tooth,

but what one in fact sees is the same tooth reappearing at intervals along the length of the worm. The usual screw nomenclature applies: a one-toothed worm is called single thread or single start; a worm with more than one tooth is called multiple thread or multiple start. The helix angle of a worm is not usually specified. Instead, the lead angle, which is equal to 90 degrees minus the helix angle, is given.

In a worm-and-gear set, the worm can always drive the gear. However, if the gear attempts to drive the worm, it may or may not succeed. Particularly if the lead angle is small, the gear's teeth may simply lock against the worm's teeth, because the force component circumferential to the worm is not sufficient to overcome friction. Worm-and-gear sets that do lock are called self locking, which can be used to advantage, as for instance when it is desired to set the position of a mechanism by turning the worm and then have the mechanism hold that position. An example is the machine head found on some types of stringed instruments.

If the gear in a worm-and-gear set is an ordinary helical gear only a single point of contact will be achieved. If medium to high power transmission is desired, the tooth shape of the gear is modified to achieve more intimate contact by making both gears partially envelop each other. This is done by making both concave and joining them at a saddle point; this is called a cone-drive or "Double enveloping"

Worm gears can be right or left-handed, following the long-established practice for screw threads

xi. Non-circular

Non-circular gears

Non-circular gears are designed for special purposes. While a regular gear is optimized to transmit torque to another engaged member with minimum noise and wear and maximum efficiency, a non-circular gear's main objective might be ratio variations, axle displacement oscillations and more. Common applications include textile machines, potentiometers and continuously variable transmissions.

xii. Rack and pinion

Rack and pinion gearing

A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into the left-to-right motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for instance, the tooth shape of an interchangeable set of gears may be specified for the rack (infinite radius), and the tooth shapes for gears of particular actual radii are then derived from that. The rack and pinion gear type is employed in a rack railway.

xiii. Epicyclic

Epicyclic gearing

In epicyclic gearing one or more of the gear axes moves. Examples are sun and planet gearing (see below) and mechanical differentials.

xiv. Sun and planet

Sun and planet gearing was a method of converting reciprocating motion into rotary motion in steam engines. It was famously used by James Watt on his early steam engines in order to get around the patent on the crank.

In the illustration, the sun is yellow, the planet red, the reciprocating arm is blue, the flywheel is green and the driveshaft is grey.

xv. Harmonic drive

Harmonic drive gearing

A harmonic drive is a specialized gearing mechanism often used in industrial motion control, robotics and aerospace for its advantages over traditional gearing systems, including lack of backlash, compactness and high gear ratios.

xvi. Cage gear

Cage gear in Pantigo Windmill, Long Island

A cage gear, also called a lantern gear or lantern pinion has cylindrical rods for teeth, parallel to the axle and arranged in a circle around it, much as the bars on a round bird cage or lantern. The assembly is held together by disks at either end into which the tooth rods and axle are set. Lantern gears are more efficient than solid pinions, and dirt can fall through the rods rather than becoming trapped and increasing wear.

Sometimes used in clocks, the lantern pinion should always be driven by a gearwheel, not used as the driver. The lantern pinion was not initially favoured by conservative clock makers. It became popular in turret clocks where dirty working conditions were most commonplace. Domestic American clock movements often used them.

xvii. Magnetic gear

All cogs of each gear component of magnetic gears act as a constant magnet with periodic alternation of opposite magnetic poles on mating surfaces. Gear components are mounted with a backlash capability similar to other mechanical gearings. At low load, such gears work without touching, giving increased reliability without noise.

3.2.3Identify gearmeshingandbacklash.

In a pair of gears backlash is the amount of clearance between the meshing tooth. Backlash unavoidable for nearly all reversing mechanical components that are coupled but could be minimized. 

3.2.4 Explain coupling concept into gear system.

When power transmission occurs between two or more pairs of gears drive and driven, gear pairs serves as a coupling.

Gears As A Coupling;

• Gears are also used to connect two nominally coaxial shafts. • This joint allows for minor misalignments such as installation errors and changes in

shaft alignment due to operating conditions. • Each joint consists of a 1:1 gear ratio internal/external gear pair.• The tooth flanks and outer diameter of the external gear are crowned to allow for

angular displacement between the two gears. • Purpose of couplings is to join two pieces of rotating equipment while.

3.2.5Identifygearmaintenancepracticesuchasdailyroutine inspection.

The routine inspection includes of;

a. LUBRICATIONIn order for a gear drive to operate at all time, it must be supply with an adequate lubricant. Check the oil level or grease and change if necessary.

b. VIBRATIONSIn order for a gear drive to operate satisfactory, it must run within safe vibration limits. If the vibration parameters (amplitude, velocity or acceleration) change with time above a given limit, it could also means something is wrong.

c. ALIGNMENTIf the alignment of a gear drives to the connected load is not made carefully the coupling may fail. The coupling can then transmits bending moments back into gear drives.

d. BACKLASHCheck the backlash of a gear drives using filler gauge, dial test indicator or sheet materials.

e. GEAR TOOTH WEARCheck for tooth surface deterioration and tooth breakage by visual inspection.

f. TOOTH CONTACTThe most satisfactory way of checking tooth contact is to apply a very thin coating of engineers marking blue or other marking medium. The tooth contact will indicate the proper gears mesh of a gear drives to rotate smoothly.

3.2.6 Assembleanddisassembleafewtypesofgearsa practical.As an examples componentscanbeuseisassemblyspurgearexercise or assemblyspur wheel /wormgear station.

ATTACHMENT

1. LAB SHEET FOR STUDENT:

POLITEKNIK I

BRAHIMSULTANFACULTYOFMECHANICALENGINEERING

DIPLOMA INMECHANICALENGINEERING

REPORTJJ615 MECHANICALCOMPONENTS & MAINTENANCE (GEAR

DRIVES)CLO:1. Assemble correctly mechanical component base on service manual

maintenancebygroup.(P5)

2. Organize properly maintenance procedure base on standard operation

procedure.(A4)

1.

NAME:

REGISTERATIONNO: SESSION:

PROGRAMME

PRACTICAL DATE SUBMITTED DATE

LECTURER

PREPAREDBY:

NOR HISHAM BIN SUHADI

CHECKEDBY:

(HEADOFDEPARTMENT/HEADOFPROGRAMME)

RUBRICSLearningDomain (LD1)Knowledge

Tools 5@3@1/5 (x4)

Procedure/Sketches 5@3@1/5 (x5)

Maintenance Procedure 5@3@1/ 5(x5)

Discussion/Conclusion 5@3@1/ 5(x3)

Neatness/Teamwork/cooperation 5@3@1/ 5(x3)

TOTALMARKS /100 x 30% =

TITLE : ASSEMBLE AND DISASEMBLE OF GEAR DRIVE SYSTEM

1.0 COURSE LEARNING OUTCOMES

Upon completion of this workshop, students should be able to :1.1 Assemblecorrectlymechanicalcomponent base onservicemanualmaintenance by group. (P4)1.2 Organizeproperlymaintenanceprocedurebaseonstandardoperation procedure.(A4)1.3 Practice safety procedures correctly in the working workshop according to the workshop safety regulation to create a secure practical team work (A3).

2.0 OBJECTIVES2.1 Producemaintenanceprocedure for a gear drives drives.2.2 Assembleanddisassembleagear drives system as a practical.As an examplescomponentcanbeuse is gear station unit.

3.0 APPARATUS/EQUIPMENT3.1 Gear Station 3.2 Hand Tools 3.3 Power Tools 3.4 Lubricant

3.4 Solvent3.5 Air Compressor

4.0 SAFETY AND HEALTH

It is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy.4.1 Always know the hazards associated with the equipment/materials that are being utilized in the workshop.4.2 Always wear appropriate protective clothing and equipment.4.3 Confine long hair and loose clothing. Do not wear high-heeled shoes, open-toed shoes, sandals or shoes made of woven material.4.4 Be familiar with the location of emergency equipment such as fire alarm and fire extinguisher. Know the appropriate emergency response procedures.

5.0 INTRODUCTION

A gear is a rotatingmachine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, magnitude, and direction of a power source. The most common situation is for a gear to mesh with another gear, however a gear can also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.

The gears in a transmission are analogous to the wheels in a pulley. An advantage of gears is that the teeth of a gear prevent slipping.

When two gears of unequal number of teeth are combined a mechanical advantage is produced, with both the rotational speeds and the torques of the two gears differing in a simple relationship.

In transmissions which offer multiple gear ratios, such as bicycles and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term is used to describe similar devices even when gear ratio is continuous rather than discrete.

6.0 TOOLS:

NO TOOLS DESCRIPTION TOOLS USAGE

7.0 DIASSEMBLE AND ASSEMBLE PROCEDURES:

NO EXPLANATION FIGURES/SKETCHES1

2

3

4

.

ETC

8.0 COMPLETE MAINTENANCE PROCEDURE FOR A GEAR DRIVES

9.0 DISCUSION / CONCLUSION

1. PRACTICLE RUBRIC

RUBRIC FOR COMBINE GEAR DRIVE SYSTEM PRACTICLE

Generic Student

Attributes (GSA) /

Learning Domain

(LD)

Skills / Aspects

ExcellentVery Good

Good Fair Unsatisfactory

  5 4 3 2 1

LD 2 / Practical

Skills Gear Drives

A) Demonstrate the proper use of various types of hand tool and power tools.

Able to select/choose various types of hand tools and power tools. Able to use various types of hand tools and power tools with the proper function of the tools.

Able to use various types of hand tools and power tools with the proper function of the tools.

Unable to use various types of hand tools and power tools with the proper function of the tools.

B) Assemble and disassemble of gear drive system

Able to select / choose various types of hand tool and power tools to assemble and disassemble belt drive system. Able to use various types of hand tools and power tools with the proper function of the tools to assemble and disassemble belt drive system.

Able to use various types of hand tools and power tools with the proper function of the tools to assemble and disassemble belt drive system.

Unable to use various types of hand tools and power tools with the proper function of the tools to assemble and disassemble of belt drive system.

c) Alignment of gear drive.

Able to select / choose the tool for shafts and gears alignment. Able to use tools for shafts and gears alignment.

Able to use tools for shafts and gears alignment.

Unable to use tools for shafts and gears alignment.

3.2.7Developmaintenanceprocedure for a gear drive system.

Belt Drives in Power Transmission

A belt is a looped strip of flexible material, used to mechanically link two or more rotating shafts.

They may be used as a source of motion, to efficiently transmit power, or to track relative movement. Belts are looped over pulleys.

In a two pulley system, the belt can either drive the pulleys in the same direction, or the belt may be crossed, so that the direction of the shafts is opposite.

Figure 3.1: Belt Drive

3.3.1 List of Belt Drives Applications

Transmit PowerA combination of mechanical components to change the speed or torque of mechanical energy. Transmit power is achieved by specially designed belts and pulleys. One or both of the pulleys are powered to moving the belt. The powered pulley is called the drive pulley while the unpowered pulley is called the idler.

Figure 3.2: Power transmission using belt drive

Conveyor.A conveyor system is mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transportation of heavy or bulky materials

Figure 3.3: Conveyor

Industries using these applications are:

• Automotive • Blenders • Converting • Conveyors • Farming • Feeder Drives • Food Processing • Electrical generators • Robotics

• Medical • Mixers • Movie Animation • Office Machines • Packaging • Electrical generators • Power Transmission

Distributors• Material Handling

3.3.2 5 Types Of Belt Drives

Table 3.1: Types of Belt Drives

1. Flat belts - used to transfer power from the engine's flywheel. It can deliver high power at high speeds (500 hp at 10,000 ft/min), in cases of wide belts and large pulleys. It can deliver high power at high speeds (500 hp at 10,000 ft/min), in cases of wide belts and large pulleys. Flat belts were traditionally made of leather or fabric. Today some are made of rubber or polymers.

2. Round belts - Round belts are a circular cross section belt designed to run in a pulley with a 60 degree V-groove. Round grooves are only suitable for idler pulleys that guide the belt, or when (soft) O-ring type belts are used. The V-groove transmits torque through a wedging action, thus increasing friction. Nevertheless, round belts are for use in relatively low torque situations only and may be purchased in various lengths or cut to length and joined, either by a staple, a metallic connector (in the case of hollow plastic), gluing or welding (in the case of polyurethane). Early sewing machines utilized a leather belt, joined either by a metal staple or glued, to great effect.

3. Vee belts - (also known as V-belt or wedge rope) solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life. They are generally endless, and their general cross-section shape is trapezoidal (hence the name "V"). The "V" shape of the belt tracks in a mating groove in the pulley (or sheave), with the result that the belt cannot slip off. Optimal speed range is 1000–7000 ft/min.

4. Multi-groove belts or polygroove belt - is made up of usually 5 or 6 "V" shapes alongside each other. This gives a thinner belt for the same drive surface, thus it is more flexible, although often wider. The added flexibility offers an improved efficiency, as less energy is wasted in the internal friction of continually bending the belt. In practice this gain of efficiency

causes a reduced heating effect on the belt and a cooler-running belt lasts longer in service. They can run over pulleys on the ungrooved back of the belt.

5. Ribbed belt - is a power transmission belt featuring lengthwise grooves. It operates from contact between the ribs of the belt and the grooves in the pulley. Its single-piece structure is reported to offer an even distribution of tension across the width of the pulley where the belt is in contact, a power range up to 600 kW, a high speed ratio, serpentine drives (possibility to drive off the back of the belt), long life, stability and homogeneity of the drive tension, and reduced vibration. The ribbed belt may be fitted on various applications: compressors, fitness bikes, agricultural machinery, food mixers, washing machines, lawn mowers, etc.

6. Film belts - though often grouped with flat belts, they are actually a different kind. They consist of a very thin belt (0.5-15 millimetres or 100-4000 micrometres) strip of plastic and occasionally rubber. They are generally intended for low-power (10 hp or 7 kW), high-speed uses, allowing high efficiency (up to 98%) and long life. These are seen in business machines, printers, tape recorders, and other light-duty operations.

7. Toothed belts (also known as timing, notch, cog, or synchronous belts) - are positive transfer belts and can track relative movement. These belts have teeth that fit into a matching toothed pulley. When correctly tensioned, they have no slippage, run at constant speed, and are often used to transfer direct motion for indexing or timing purposes. They can bear up to 200 hp (150 kW) at speeds of 16,000 ft/min.

* choose 5 types only

3.3.3 Belt tension and misalignment of belt drivesBelt tension

• The ideal belt is that of the lowest tension which does not slip in high loads. • Belt tensions should also be adjusted to belt type, size, speed, and pulley

diameters.• Belt tension is determined by measuring the force to deflect the belt a given

distance per inch of pulley. • Timing belts need only adequate tension to keep the belt in contact with the

pulley.

Figure: 3.4: belt tensioner

Misalignment Belt drive misalignment exists when the driver and driven sheaves are not

properly aligned. Misalignment can take either the form of angular or parallel (offset)

misalignment, or a combination of both. Angular misalignment occurs when the faces of the sheaves do not form a straight

line. With parallel misalignment, the sheaves may be in angular alignment, but their

position on the shaft creates a parallel offset.

Angular misalignment. Parallel misalignment.

Figure 3.5: misalignment

3.3.4 Check list drive belt maintenance

There are several things need to be addressed before performing maintenance is charged which is:

Always shut off power, lock and tag control box. Place all machine components in safe position.

Remove guard, inspect and clean. Inspect belt for wear, damage. Replace as needed. Inspect sheaves or sprockets for wear, alignment. Replace if worn. Inspect other drive components such as bearings, shafts, motor mounts and take

up rails. Inspect static conductive grounding system (if used) and replace components as

needed. Check belt tension and adjust as needed. Recheck pulley alignment. Reinstall belt guard. Restart drive. Look and listen for anything unusual.

Table 3.2: Table of symptoms, probable cause and solution

PREMATURE BELT FAILURE

SYMPTOMS PROBABLE CAUSE SOLUTION

Broken belt

1.Under-designed drive 1. Redesign using Drive Design Manual.

2.Belt rolled or prised onto pulley

2. Use drive take up when installing.

3.object falling into drive3. Provide adequate guard or drive protection.

4.Severe shock load4. Redesign to accommodate shock load.

Belt fail to carry load (slip);no visible reason

1.Under-designed drive1. Redesign using Drive Design Manual

2.Damaged tensile member2. Follow correct installation procedure.

3.Worn pulley grooves3. Check for groove wear. Replace as needed.

4.Contre distance movement4. Check drive for centre distance movement during operation.

Edge cord failure1.Pulley misalignment

1. Check and correct alignment.

2.Damaged tensile member2. Follow installation procedure.

Belt delamination or under cord separation

1.Pulleys too small1. Check and design, replace with larger pulleys.

2.Back idler too small2. lncrease back idler to acceptable diameter.

Wear on belt top surface1.Rubbing against guard 1. Replace or repair guard.2.ldler malfunction 2. Replace idler.

Wear on belt top corner1.Belt-to-pulley fit incorrect(belt too small for groove)

1. Use correct belt-to-pulley combination.

Wear on belt bottom corners

1.Belt slip1.Retension until slipping stops

2.Misalignment 2. Realign pulleys.3.Worn pulleys 3. Replace pulleys.

4.lncorrect belt4. Replace with correct belt size.

SEVERE OR ABNORMAL BELT WEAR

SYMPTOMS PROBABLE CAUSE SOLUTION

Wear on belt bottom corners1.Belt-to-pulley fit incorrect

1. Use correct belt-to-pulley combination.

2.Worm pulleys 2. Replace pulleys.

Wear on belt bottom corners

1.Belt bottoming on pulley groove

1. Use correct belt/pulley match.

2.Worn pulleys 2. Replace pulleys.3.Deberis in pulleys 3. Clean pulleys.

Under cord cracking

1.Pulley diameter too small1. Use larger diameter pulleys.

2.Belt slip 2. Retension.3.Back idler too small 3. Use larger diameter back

idler.

4.lmproper storage4. Do not coil belt too tightly, kink or bend. Avoid heat and direct sunlight.

Burn or hardening on bottom or sidewall

1.Belt slip1. Retension until slipping stops.

2. Worn pulleys 2. Replace pulleys.

3. Under-designed drive3. Redesign using drive Design Manual

4. Shaft movement4. Check for centre distance changes

Extensive hardening of belt exterior

1.Hot drive environment 1.Improve ventilation to drive

Belt surface flaking, sticky or swollen

1.Oil or chemical contamination

1. Do not use belt dressing. Eliminate sources of oil, grease or chemical contamination.

BANDED (JOINED)BELT PROBLEMS

PROBABLE CAUSE SOLUTION

SYMPTOMS

Tie-band separation1.Worn pulleys 1. Replace pulleys.

2. improper groove spacing2. Use standard groove pulleys

Top of tie-band frayed, worn or damaged

1. Interference with guard 1. Check guard.2. Back idler malfunction or damaged

2. Repair' or replace back idler.

comes off drive 1.Debris in pulleys1. Clean grooves. Use single belts to prevent debris from being trapped in grooves.

One or more ribs run outside of pulley

1.Misalignment 1. Realign drive.2. Under tensioned 2. Retension.

BELT NOISE AND UNUSUAL VIBRATITION

SYMPTOMSPROBABLE CAUSE SOLUTION

Squeal or "chirp"1.Belt slip 1. Retension.2. Contamination 2.Clean belts and pulleys

Slapping noise

1.Loose belts 1. Retension.2. Mismatched set 2. Install matched belt set.

3. Misalignment3. Realign pulleys so all belts share load equally

Rubbing sound Guard interference1. Repair, replace or redesign guard.

Grinding sound Damaged bearings Replace, align and lubricate

Unusually loud drive

1.Incorrect belt

1. Unusually loud drive23Use correct belt size. Use correct belt tooth profile for sprockets on synchronous drive.

2.Worn pulleys 2. Replace pulleys.

3. Debris in pulleys 3. Clean pulleys, improve shielding, and remove rust, paint or dirt from grooves.

Excessive vibration in drive system

1.Incorrect belt1. Use correct belt cross-section in pulley.

2. Poor machine or equipment design

2. Check structure and brackets for adequate strength.

3. Pulley out of round 3. Replace pulley.4. Loose drive components 4. Check machine

components and guards, motor mounts, motor pads,

bushings, brackets and framework for stability, adequate design strength, proper maintenance and proper installation.

WIBELT STRETCHESBEYONDPROBLEM WITH SHEAVES, BELT STRETCHES BEYOND TAKE UP

SYMPTOMS PROBABLE CAUSE SOLUTION

Multiple belts stretch unequally

1.Misaligned drive 1. Realign and retension drive.

2. Debris in pulleys 2. Clean pulleys.3. Broken tensile member or cord damaged

3. Replace all belts, install properly.

4. Mismatched belt set 4. Install matched belt set

Single belt, or where all belts stretch evenly

1.Insufficient takeup allowance

1. Check takeup. Use allowance specified in Drive Design Manual.

2. Grossly overloaded or under-designed drive

2. Redesign drive.

3. Broken tensile members3.Replace belt, install properly

V-BELT TURN OVER OR JUMP OFF SHEAVE

SYMPTOMS PROBABLE CAUSE SOLUTION

lnvolves single or multiple belts

1.Shock loading or vibration 1. Check drive design. 2. Foreign material in grooves

2. Shield grooves and drive.

3. Misaligned pulleys Worn pulley grooves

3. Realign pulleys.

4. Worn pulley grooves 4. Replace pulleys.

5. Damaged tensile member5. Use correct installation and belt storage procedure.

6. Incorrectly placed flat idler pulley

6. Carefully place flat idler on slack side of drive as close as possible to driver pulleys.

7. Mismatched belt set7. Replace with new set of matched belts. Do not mix old and new belts

8. Poor drive design 8. Check for centre distance stability and vibration

dampening.

3.4 Chain Drive in Power Transmission

3.4.1 General

A chain drive uses a sprocket and chain to drive machinery much like the belt drive. However, since the belt drive uses friction to drive machinery, slippage can occur. The chain drive is a positive or direct drive and does not allow slippage. A simple example of a chain drive is the sprocket and chain on a bicycle or motorcycle.

The three basic applications of chain drive are:

1.Transmitting Power, chains and sprockets are used as flexible gearing to transmit torque from one rotating shaft to another.

2.Converting Motion, chains are used to convey materials by sliding, pushing, pulling or carrying.

3. Timing or Synchronizing, chains are used as devices to synchronizing movements such as valve timing in automobiles or raising loads on an overhead chain hoist

3.4.2 TYPES OF CHAIN DRIVE

1. Roller chains are used in low- to mid-speed drives at around 600 to 800 feet per minute

2. A bicycle chain is a form of roller chain. Bicycle chains may have a master link, or may require a chain tool for removal and installation. A similar but larger and thus stronger chain is used on most motorcycles

3. In automobile engines, roller chains would drive the camshaft(s) off the crankshaft, generating less noise than a gear drive as used in very high performance engines, and more durable than timing belts.4. Chains are also used in forklifts using hydraulic rams as a pulley to raise and lower the carriage; however, these chains are not considered roller chains, but are classified as lift or leaf chains.

5. Chainsaw cutting chains superficially resemble roller chains but are more closely related to leaf chains. They are driven by projecting drive links which also serve to locate the chain onto the bar.

6. Silent Chains are used for the camshaft drive of the mid- to large-size engines. Transfer-case drive in four-wheel-drive vehicle.The primary drive between the engine and transmission, as well as in other high-speed applications.

Sprockets

Sprockets types.

The three bacis sprockets types are identified by their hub arrangement.

Type A sprockets sometimes called plate sprockets, have no hubs and are used for mounting on flanges, hubs or other devices . They are made from bar stock or hot-rolled plate in either solid or split construction with plain, countersunk, or tapped holes. Holes sizes and bolt circle for which jigs are available are indicated in the thye D sprocket .

Type B sprockets have a hub on one side only. Small and medium size sprockets are usually furnised in type B and are turned from bar stock or forgings, or are made by welding a bar stock hub to a hot-rolled plate sprocket. If required, large diameter type B sprockets can be furnished. They can be welded hub construction or machined from gray iron castings.

Type C sprockets have hubs on both sides. Large diameter sprockets are furnised in type C, with hub projections equidistant from the centerline of the sprockets. With this hub arrangement the line of action due to chain pull reacts through the center of the hub, proving stability and assuring an even distribution of stress on shafts and key. Offset hubs can be furnished.Type C sprockets are normally machined from gray iron castings, but can be cast steel or welded hub construction.

Multiple width sprockets have a row of theeth to engage each strand of chain. They are made in the same types as single width sprockets. That is smaller diameter sprockets are reguarly furnished as type B and the larger sizes as type C.Mandrel bore sprockets are made in broad range of sizesfor single and multiple strand chain.They are stockedwith mandrel bores for remaining to suit specification.

Finished bore sprockets are available for most widely used single strand chain. These ready to use sprockets are made in type B only and are stocked in a range of popular bores , complete with keyseats and set screw.

Taper lock sprockets are ideal where a positive, full compression grip on the shaft is desired. They are available in a wide range of sizes for single and double strand chains. Bushing are stocked in with bore increment, complete with key seat.

Special purpose sprockets. Type C split sprockets are used to facillate the installation or replacement of sprockets locate where accessibility is difficuilt. They have a special split hub and rim construction design for bolting the sprocket halves securely together.

Type D double duty sprockets offer convenience and economy when occasional drive ratio change are necessary. They consists of a Type A plate sprocket bolted to a gray iron hub .

Shear pin sprockets are used to protect chain Drives and machinery from damage overloads.

They consists of a modified Type sprocket mounted on a gray iron hub and connected by a shear pin. Many stock sizes are available.

Double pitch sprockets

Standard rollers.

Series C-2000 chains have rollers of the same diameters and widths as American Standard Roller chains of one half the conveyor chain pitch. Engaged by every other tooth, double duty sprockets have two teeth per chain pitch. During each revolution only half the teeth function effectively. Sprockets with odd numbers of teeth will allow any given tooth to engage only on every other revolution, automatically increasing sprocket life. Double duty sprockets with even number of teeth may be manually advance one tooth periodically to increase sprocket life. Martin stock C-2000 series sprockets are furnished double duty only.

Carrier rollers

Sprockets for the C-2000 series chain can roller are cut with space cutters or standard halve for the American Standard Roller chain of the same diameter. Each sprocket tooth meshes with these chains. Double sprockets cannot made for double pitch chain with Carrier Rollers. For drives of 31 teeth or more we recommend using Standard sprockets with series C2000 series chain. All altered double pitch sprockets requiring all way will be furnished with key way on center of tooth unless otherwise specified.

3.4.3 Installation.

To obtain maximum chain and sprocket life accurate alignment, proper chain tension , and good lubrication are required. A drive is easy to install provided that precautions common to sound judgement and good workmanship are followed. Poor installation eventually becomes evident in the resulting reduction of chain life- more so on a high speed drive than on a low speed drive.Simple precautions are sometimes forgotten, but they are essential-All parts of the drive must be rigidly and securely mounted so that vibration cannot work them loose.

1.The chain must be clean and free from grit and dirt before it is installed. Korosene is highly effective cleaning agent.

2.The chain should articute freely. Make sure that parts are not damaged or bent and that sprockets and shafts operate freely.

3.The drive must have adequate clearance . If chain case lubrication is used the drive must be positioned correctly for chain clearance and the oil spray pipe adjusted properly. During the start – up of the drive , make certain that all parts work smoothly and lubrication is being properly applied to the chain.

Shaft and sprocket Alignment.

Mount the sprockets on their respectively shaft and align shafts horizontally with a machine’s level. Parallel alignment of the shaft should be made with a vernier caliper, or a feeler bar and the distance between shafts on both sides of the sprocket should be equal. Sprocket tooth engagement:- a straight edge or a taut wire may be applied to the machined surface of the sprocket to assist in this alignment . Set screw must be tightened securely in the sprocket hub to hold key in position and to guard against any lateral movement in the sprocket motors,

bearingetc, should then be bolted securely in place so that full alignment can be maintained during the operation of the drive.

To Install.

1. Select the sprocket and bushing required and slide the bushing into the sprocket. Be sure that all holes match up.

2. Place screws in threaded engagement with sprocket and free in bushing holes. Slip assembled sprocket and bushing on shaft.

3. Tighten screws to force tapered bushing into the taper-bored hub . This wedges the bushing between the shaft and sprocket assuring the fit that is as tight as a shrunk fit.

To removed

1. Removed the screws completely . Using one of them as a jackscrew, insert in hole threaded on bushing so that it engages the bushing and is free of the hub. Tighten the jackscrew.

2. As the jackscrew is tightened , the sprocket will become disengaged from the bushing and the complete assembly may be easily slipped of the shaft.

Checking sprockets for wear.

To check for sprocket wear is easier, most can be seen by eye, but to be sure the wisest way is to try a new chain in the teeth and see how much wear has taken place by the clearance that is found between the teeth and the rollers or in between the side plates and the side of the sprocket wall. Scored teeth or teeth with their tips worn off are also signs of wear, the charts in this booklet will explain what corrections must take place to prevent the trouble from happening again.The examples of teeth damage can be easily by making sure that the chain is in good condition and by ensuring that the sprockets are in line as well as being made of hardened steel. Normal wear may also cause some tooth damage but it is usually all over type of wear and not limited to just one side or one edge of the sprocket tooth.

3.4.4 CHAIN DRIVE MAINTENANCE

1.Check lubrication -

On slow speed drives, where manual lubrication is used, be sure the lubrication schedule is being followed. If the chain is covered with dirt and debris, clean the chain with kerosene and relubricate it.

WARNING! NEVER USE GASOLINE OR OTHER FLAMMABLE SOLVENTS TO CLEAN A CHAIN. A FIRE MAY RESULT.

If drip lubrication is used, check for adequate oil flow and proper application to the chain. With bath or pump lubrication, check oil level and add oil if needed. Check oil for contamination and change oil if needed. Change oil after the first 100 hours of operation and each 500 hours thereafter. If pump lubrication is used, check each orifice to be sure it is clear and is directing oil onto the chain properly.

2. Check Chain Tension -

Check chain tension and adjust as needed to maintain the proper sag in the slack span. If elongation exceeds the available adjustment, remove two pitches and reconnect the chain.

3. Check Chain Wear -

Measure the chain wear elongation and if elongation exceeds functional limits or is greater than 3% (.36 inches in one foot) replace the entire chain. Do not connect a new section of chain to a worn chain because it may run rough and damage the drive. Do not continue to run a chain worn beyond 3% elongation because the chain will not engage the sprockets properly and it may damage the sprockets.

4. Check Sprocket Tooth Wear -

Check for roughness or binding when the chain engages or disengages from the sprocket. Inspect the sprocket teeth for reduced tooth section and hooked tooth tips.

If these conditions are present, the sprocket teeth are excessively worn and the sprocket should be replaced. Do not run new chain on worn sprockets as it will cause the new chain

to wear rapidly. Conversely, do not run a worn chain on new sprockets as it will cause the new sprockets to wear rapidly.

5. Check Sprocket Alignment -

If there is noticeable wear on the inside surface of the chain roller link plates, the sprockets may be misaligned. Realign the sprockets as outlined in the installation instructions to prevent further abnormal chain and sprocket wear.

6. Check for Drive Interference -

Check for interference between the drive and other parts of the equipment. If there is any, correct it immediately. Interference can cause abnormal and potentially destructive wear on the chain or the interfering part. If the edges of the chain link plates impact against a rigid part, link plate fatigue and chain failure can result.

Check for and eliminate any buildup of debris or foreign material between the chain and sprockets.

A RELATIVELY SMALL AMOUNT OF DEBRIS IN THE SPROCKET ROLL SEAT CAN CAUSE TENSILE LOADS GREAT ENOUGH TO BREAK THE CHAIN IF FORCED THROUGH THE DRIVE.

7. Check for Failure -

Inspect the chain for cracked, broken or deformed parts. If any of these conditions are found, REPLACE THE ENTIRE CHAIN, even though portions of the chain appear to be in good condition. In all likelihood, the entire chain has been damaged.

3.5 COUPLED SHAFT ALIGNMENT

3.5.1 Fundamentals of shaft alignment

• A shaft is a rotating member, usually of circular cross section used to transmit torque and rotation, to connect other components

• Types Of Misalignment

• Parallel / Off-Set Misalignment

• Angular Misalignment

• Combination Misalignment

Tools to measure shaft axis alignment condition

• it is possible to measure the alignment with dial gauges or feeler gages using various mechanical setups.

• it is recommended to take care of bracket sag, parallax error while reading the values.

• it is very convenient to use laser shaft alignment technique to perform the alignment task within highest accuracy.

• it is required to align the machine better, the laser shaft alignment tool can help to show the required moves at the feet positions.

Requirements of good shaft alignment

• it should be easy to connect or disconnect attached components.

• it should transmit the full power from one shaft to other without losses.

• it does allow some misalignment between the two adjacent shaft rotation axis.

• it is the goal to minimize the remaining misalignment in running operation to maximize power transmission and to maximize machine runtime (coupling and bearing and sealing lifetime).

• it should have no projecting parts.

• it is recommended to use manufacturer's alignment target values to set up the machine train to a defined non-zero alignment, due to the fact that later when the machine is at operation temperature the alignment condition is perfect

VARIABLE SPEED DRIVES

CONTINUOS VARIABLE TRANSMISSION

• A transmission that can change steplessly through an infinite number of effective gear

ratios between maximum and minimum values.

• The flexibility of a CVT allows the input shaft to maintain a constant angular velocity over a range of output velocities.

Types Of CVT

• Variable-diameter pulley (VDP) or Reeves drive

• Toroidal or roller-based CVT (Extroid CVT )

• Magnetic CVT or mCVT

• Infinitely Variable Transmission (IVT)

• Ratcheting CVT

• Hydrostatic CVTs

• Cone CVTs

• Radial roller CVT

• Planetary CVT

LAB SHEET

REPORTJJ615 MECHANICALCOMPONENTS &

MAINTENANCECLO:

1. Assemble correctly mechanical component base on service manual

maintenancebygroup.(P5)

2. Organize properly maintenance procedure base on standard operation

procedure.(A4)

2.

NAME:

REGISTERATIONNO: SESSION:

PROGRAMME

PRACTICAL DATE SUBMITTED DATE

LECTURER

PREPAREDBY:RUBRICS

LearningDomain (LD1)Knowledge

NOR HISHAM BIN SUHADI

CHECKEDBY:

(HEADOFDEPARTMENT/HEADOFPROGRAMME)

Introduction 5@3@1/5 (x4)

Procedure/Tools 5@3@1/5 (x5)

Maintenance Procedure 5@3@1/ 5(x5)

Discussion/Conclusion 5@3@1/ 5(x3)

Neatness/Teamwork 5@3@1/ 5(x3)

TOTALMARKS /100 x 30% =

TITLE : CHAIN DRIVES

5.0 COURSE LEARNING OUTCOMES Upon completion of this workshop, students should be able to :1.1 Assemblecorrectlymechanicalcomponent base onservicemanualmaintenance by group. (P4)1.2 Organizeproperlymaintenanceprocedurebaseonstandardoperation procedure.(A4)1.3 Practice safety procedures correctly in the working workshop according to the workshop safety regulation to create a secure practical team work (A3).

6.0 OBJECTIVES

2.1 Demonstratetheuseof thereversedialindicatormethodsto correct shaft misalignment.2.2 Assembleanddisassembleofmechanicaldrivesystemasa practical.Asanexamplesapparatuscanbeusearegear assemblyforcombined drivesandalignment of drives, chain drives and belt drives.

7.0 APPARATUS/EQUIPMENT3.1 Chain Drive system

3.2 Hand Tools 3.3 Power Tools 3.4 Lubricant 3.4 Solvent

3.6 Air Compressor

4.0 SAFETY AND HEALTHIt is the individual’s responsibility to practice the following general safety guidelines at all times and keep your workspace reasonably tidy.4.1 Always know the hazards associated with the equipment/materials that are being utilized in the workshop.4.3 Always wear appropriate protective clothing and equipment.4.3 Confine long hair and loose clothing. Do not wear high-heeled shoes, open-toed shoes, sandals

or shoes made of woven material.4.4 Be familiar with the location of emergency equipment such as fire alarm and fire extinguisher. Know the appropriate emergency response procedures.

10.0 INTRODUCTION

A shaft is a rotating member, usually of circular cross section used to transmit torque and rotation, to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement between them. It provides the axis of rotation, or oscillation of elements such as gears, pulleys, sprockets, flywheels and the like and controls the geometry of their motion.

Shafts are carriers of torque: they are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia.

The designing of shaft must be studied from the following point of view:

1- Deflection and rigiditya. Torsional deflectionb. Slope at bearings and shaft supported elementsc. Shear deflection due to transverse loading of short shafts

2- Stress and strength

a. Static strength

b. fatigue strength

c. Reliability

Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles.

Most often, the power is conveyed by a roller chain, known as the drive chain or transmission chain, passing over a sprocket gear, with the teeth of the gear meshing with the holes in the links of the chain. The gear is turned, and this pulls the chain putting mechanical force into the system.

Sometimes the power is output by simply rotating the chain, which can be used to lift or drag objects. In other situations, a second gear is placed and the power is recovered by attaching shafts or hubs to this gear. Though drive chains are often simple oval loops,

they can also go around corners by placing more than two gears along the chain; gears that do not put power into the system or transmit it out are generally known as idler-wheels. By varying the diameter of the input and output gears with respect to each other, the gear ratio can be altered.

11.0 ASSEMBLE AND DISASSEMBLE PROCEDURES

NO EXPLANATION FIGURES/SKETCHES TOOLS1

2

3

ETC

7.0 MAINTENANCE PROCEDURE FOR CHAIN DRIVE :

8.0 DISCUSION / CONCLUSION

4KamalBin Haron (PSA)

Zulkhairi BinKhairudin(PSA)

4.0 BEARING

4.1 Bearing Concepts

4.1.1 Application of bearings

• A bearing is a machine element that constrains relative motion between moving parts to only the desired motion.

• The design of the bearing may provide for free linear movement of the moving part or for free rotation around a fixed axis or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.

• Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.

• Bearing are used to support rotating shaft and are classified according to the direction of the main load. (see figure 4.1.1)

axial bearing are design to withstand axial thrust Radial bearings are designed to withstand radial load Combination of both

BEARING

Learning OutcomesUpon completion of this chapter, students should be able to:-

1. Understandbearingconcepts.2. Understandfriction, temperature andlubrication.3. Describe mountinganddismountingofbearing.4. Understandbearingdamage.

Figure 4.1.1

• A bearing is constituted by an inner and an outer ring. Between them a series of rolling element is found

• Something a fourth element (cage) is present to keep the rolling elements in their position.

• Rolling elements can be spheres (ball bearing) or cylinders (cylinder roller bearings).

4.1.2 Types of bearing and characteristic of bearings

The bearings are classified broadly into two (2) categories based on the type of contact they have between the rotating and the stationary member

a. Rolling Element Bearings

Rolling element bearing also called an antifriction bearing because the created by this bearing is rolling friction rather than sliding friction creared by the plain bearings.The rolling element bearing is a cylinder containing a moving inner ring of stell balls or rollers.

Rolling element bearings have balls or roller for increase efficiency. Rolling friction is always less than sliding friction.The following are the three basic types of rolling element bearings.

i. Ball bearingsii. Roller bearings.iii. Needle Bearings.

Different designs of ball and roller bearings can handle radial, axial and combination loads. Needle bearings are used only for radial or axial loads.

Figure 4.1.2 Needle bearing

b. Sliding / Journal / Plain Bearings

A plain bearing is any bearing using a sliding action rather than a rolling action. It may or may not be lubricated. Plain bearings are sometimes referred to as journal or sleeve bearings. Plain bearings are typically cylindrical shape bearings designed to carry radial loads.The terms journal and sleeve are often used interchangeably :sleeve refers to the general configuration, and journal refer to the part of the shaft in contact with the bearings.Plain bearing may also be thrust bearings or thrust washers.Plain bearing can categorized into three classes :

i. Class IBearing systems are lubricated from an outside sources

ii. Class IIBearing systems have internal lubrication .

iii. Class IIIBearing systems have graphite , PTFE ( Teflon) or plastic bearings that require no lubricant

Figure 4.1.21 Journal Bearing

Table 4.1.22 : Two main categories based on the type of contact

Type Description Friction Stiffness Speed Life Notes

Plain/journal/sliding bearing Cylindrical sleeve that

support a rotating or sliding

shaft .The inner lining, called

the

bushing, is usually made of a

metal softer then

that’s of the shaft so that any

wear occurs in the replaceable

bushing and not in the shaft.

Depends on materials

and construction, PTFE

has coefficient of

friction ~0.05-0.35,

depending upon fillers

added

Good, provided

wear is low, but

some slack is

normally present

Low to very high Low to very high -

depends upon

application and

lubrication

Widely used, relatively high

friction, suffers from stiction

in some applications.

Depending upon the

application, lifetime can be

higher or lower than rolling

element bearings.

Rolling element bearing

Is also called an antifriction

bearing because the created

by this bearing is rolling

friction rather than sliding

friction creared by the plain

bearings.The rolling element

bearing is a cylinder

containing a moving inner ring

of stell balls or rollers.

Rolling coefficient of

friction with steel can

be ~0.005 (adding

resistance due to seals,

packed grease, preload

and misalignment can

increase friction to as

much as 0.125)

Good, but some

slack is usually

present

Moderate to high

(often requires

cooling)

Moderate to high

(depends on

lubrication, often

requires

maintenance)

Used for higher moment loads

than plain bearings with lower

friction

4.1.3 Nomenclature of Bearing

Rolling bearings include radial and thrust bearing for radial and axial load, respectively, and some bearing types which a design for combine radial and axial loads. Generally speaking , ball bearing a recommended for light to moderate load: roller bearing a recommended for heavy load . There is nine basic bearings. Some of these basic types available in many variation : for instance, cylindrical roller bearing may be obtain with one, two, or four row of roller .

Single row deep – groove ball bearings a generally available in nine different external configuration. Taper roller bearing can some in more than 20 different configuration . The other basic type do not come in large number of configuration, but it should be not that’s all types of rolling bearing are available in many design variants thus may vary greatly in internal design depending on the manufacturer.

It is not within the scope of thus handbook to describe all the various design of rolling bearing use in machinery but rather to alert maintenance personel to their existence . Details are given in manufacturer catalog or by contacting the manufacturer directly.

Example : Code number of rooling bearing

Bearing Sizes

Figure 4.1.3 : Bearing Sizes

Each bearing has an inside diameter, outside diameter and width diameter in that order. Most bearings are metric in size, but can also be imperial. On our site, each bearing shows its principal dimensions.

Example for bearing Part Number

d = Inside diameter D = Outside diameter B/T = Width diameter

4.1.4 Bearing Service Life

Basic life or L10 as defined in ISO and ABMA standards is the life that 90% of a sufficiently large group of apparently identical bearings can be expected to reach or exceed. The median or average life, sometimes called Mean Time Between Failure (MTBF), is about five times the calculated basic rating life. Service life is the life of a bearing under actual operating conditions before it fails or needs to be replaced for whatever reason. The so called specification life is generally a requisite L10 basic rating life and reflects a manufacturer's requirement based on experience with similar applications.

4.1.4.1 Calculating Loads

Engineers typically employ rolling-contact fatigue models that compare bearing load ratings to applied dynamic and static loads as they impact service life and reliability. The basic dynamic load rating covers dynamically stressed bearings that rotate under load. This rating, defined in ISO 281, is the bearing load that results in a basic rating life or L10 of 1 million revolutions. Dynamic loads should include a representative duty cycle or spectrum of load conditions and any peak loads.

The basic static load rating applies to bearings that rotate at speeds less than 10 rpm, slowly oscillate, or remain stationary under load over certain periods. Be sure to include loads of

extremely short duration (shock) because they may plastically deform contact surfaces and compromise bearing integrity.

Basic catalog or simplified calculations typically ignore elastic deformations in the bearing, housing, or machine frame, as well as moments produced in the bearing by shaft deflection. Such calculations may assume loads are constant in magnitude and direction and act radially on a radial bearing, or axially and centrically on a thrust bearing. Oftentimes, bearings in actual service see simultaneous radial and axial loads. When the resultant of radial and axial loads is constant in magnitude and direction, calculate an equivalent dynamic bearing load from:

P = XFr + YFa

where P = equivalent dynamic bearing load, lb; Fr = actual radial bearing load, lb; Fa = actual axial bearing load, lb; X = radial load factor for the bearing; and Y = axial load factor for the bearing.

For single-row radial bearings, axial load influences P only when the ratio Fa ⁄ Fr exceeds a certain limiting value. Conversely, even light axial loads are significant for double-row radial bearings. The above equation also applies to spherical thrust bearings and other thrust types that handle both axial and radial loads. Be sure to consult manufacturer catalogs for axial-radial thrust bearings because designs can vary widely. For thrust ball bearings and other types that carry pure axial loads, the equation simplifies to P = Fa, provided the load acts centrically.

4.1.4.2 Rating Life Equations

The equation from ISO 281 or the American Bearing Manufacturers Association (ABMA) Standards 9 and 11 figures basic, nonadjusted rating life by:

L10 = (C ⁄ P)p in millions of revolutions

where C = basic dynamic load rating, lb; P = equivalent dynamic bearing load, lb; p = life-equation exponent ( p = 3 for ball bearings; and p = 10/3 for roller bearings)

For bearings run at constant speed, it may be more convenient to express the basic rating life in operating hours:

L10h = (1,000,000/60)nL10 where n = rotational speed, rpm

Predicted bearing life is a statistical quantity in that it refers to a bearing population and a given degree of reliability. The basic rating life is associated with 90% reliability of bearings built by modern manufacturing methods from high-quality materials and operated under normal conditions. In practice, predicted life may deviate significantly from actual service life, in some documented cases by nearly a factor of five.

Service life represents bearing life in real-world conditions, where field failures can result from root causes other than bearing fatigue. Examples of root causes include contamination, wear, misalignment, corrosion, mounting damage, poor lubrication, or faulty sealing systems.

On going advances in bearing technology and manufacturing processes continue to extend bearing life and reduce sensitivity to severe operating conditions. Standard ISO 281 has developed in step with these advances to predict service life more accurately. The latest version expands coverage to include bearing material fatigue stress limits, and a factor for solid contamination effects on bearing life when using various lubrication systems such as grease, circulating oil, and oil bath.

The equation calculates modified rating life at n% reliability Lnm in millions of revolutions at constant speed by:

Lnm= a1aISOL10

where a1 = life-adjustment factor for reliability (1.0 for 90% reliability); and a ISO = manufacturer life modification factor according to ISO 281.

Finding a ISO involves the use of a contamination factor that considers the lubrication system type, cleanliness class, bearing size, and lubrication operating conditions as defined in ISO 4406. This contamination factor, along with the ratio of the bearing fatigue load limit to the bearing equivalent load limit, and the lubrication condition, determine a ISO. In general, better lubricant conditions and lower equivalent loads lessen bearing life sensitivity to contamination levels. Conversely, high loads and poor lubricant conditions raise bearing life sensitivity to contamination.

Figure 4.1.4.2 : Operating Regimes

4.1.5Shield and Seal Bearings

Self lubricating bearings must have seals or shields to keep oil or grease in, and protection against contamination.Shields Close-fitting but nonrubbing thin washer.Protect bearing against all but very small foreign particles and help retain lubrication.

4.2 Friction , temperature and lubrication

4.2.1 Friction in Bearing Systems

The friction in a rolling bearing is made up of several components, (see table 4.2.1) . Due to the large number of influencing factors, such as dynamics in speed and load, tilting and skewing resulting from installation, actual frictional torques and frictional power may deviate significantly from the calculated values.

 

Table 4.2.1: Frictional component and influencing factor

Frictional component Influencing factorRolling friction Magnitude of loadSliding friction of rolling elements

Sliding friction of cage

Magnitude and direction of load

Speed and lubrication conditions, running-in condition

Fluid friction (flow resistance) Type and speed

Type, quantity and operating viscosity of lubricantSeal friction Type and preload of seal

 

4.2.2 Relation between operating temperature with bearing friction

4.2.2.1 Friction

One of the main functions required of a bearing is thatit must have low friction. Under normal operating conditions rolling bearings have a much smaller friction coefficient than the slide bearings, especially starting friction.

Although the dynamic friction coefficient for rolling bearings varies with the type of bearings, load, lubrication, speed, and other factors; for normal operating conditions, the approximate friction coefficients for various bearing types are listed in Table 10.1.

4.2.2.2 Temperature rise

Almost all friction loss in a bearing is transformed into heat within the bearing itself and causes the temperature of the bearing to rise. Bearing operating temperature is determined by the equilibrium or balance between the amount of heat generated by the bearing and the amount of heat conducted away from the bearing. In most cases the temperature rises sharply during initial operation, then increases slowly until it reaches a stable condition and then remains constant. The

time it takes to reach this stable state depends on the amount of heat produced, heat capacity/diffusion of the shaft and bearing housing, amount of lubricant and method of lubrication. If the temperature continues to rise and does not become constant, it must be assumed that there is some improper function.

Possible causes of abnormal temperature include bearing misalignment (due to moment load or incorrect installation), insufficient internal clearance, excessive preload, too much or too little lubricant, or heat produced from sealed units. Check the mechanical equipment, and if necessary, remove and inspect the bear

4.2.3 Principle of bearing lubrication

Many bearings require periodic maintenance to prevent premature failure, although some such as fluid or magnetic bearings may require little maintenance.

Most bearings in high cycle operations need periodic lubrication and cleaning, and may require adjustment to minimise the effects of wear.

Bearing life is often much better when the bearing is kept clean and well-lubricated. However, many applications make good maintenance difficult. For example bearings in the conveyor of a rock crusher are exposed continually to hard abrasive particles. Cleaning is of little use because cleaning is expensive, yet the bearing is contaminated again as soon as the conveyor resumes operation. Thus, a good maintenance program might lubricate the bearings frequently but never clean them.

4.2.3.1 Packing

Some bearings use a thick grease for lubrication, which is pushed into the gaps between the bearing surfaces, also known as packing. The grease is held in place by a plastic, leather, or rubber gasket (also called a gland) that covers the inside and outside edges of the bearing race to keep the grease from escaping.

Bearings may also be packed with other materials. Historically, the wheels on railroad cars used sleeve bearings packed with waste or loose scraps cotton or wool fiber soaked in oil, then later used solid pads of cotton.

4.2.3.2 Ring oiler

Bearings can be lubricated by a metal ring that rides loosely on the central rotating shaft of the bearing. The ring hangs down into a chamber containing lubricating oil. As the bearing rotates, viscous adhesion draws oil up the ring and onto the shaft, where the oil migrates into the bearing to lubricate it. Excess oil is flung off and collects in the pool again.

4.2.3.3 Splash lubrication

Some machines contain a pool of lubricant in the bottom, with gears partially immersed in the liquid, or crank rods that can swing down into the pool as the device operates. The spinning wheels fling oil into the air around them, while the crank rods slap at the surface of the oil, splashing it randomly on the interior surfaces of the engine. Some small internal combustion engines

specifically contain special plastic flinger wheels which randomly scatter oil around the interior of the mechanism.

4.2.3.4 Pressure lubrication

For high speed and high power machines, a loss of lubricant can result in rapid bearing heating and damage due to friction. Also in dirty environments the oil can become contaminated with dust or debris that increases friction. In these applications, a fresh supply of lubricant can be continuously supplied to the bearing and all other contact surfaces, and the excess can be collected for filtration, cooling, and possibly reuse. Pressure oiling is commonly used in large and complex internal combustion engines in parts of the engine where directly splashed oil cannot reach, such as up into overhead valve assemblies.[18] High speed turbochargers also typically require a pressurized oil system to cool the bearings and keep them from burning up due to the heat from the turbine.

4.3 Mounting and dismounting of bearing.

Mounting and installation of a bearing depends on the type and its fitting practice. The procedures covered are concerned with the proper methods and tools to accomplish installation of pressed fitted bearing rings. Even though some of the tools and procedures used for mounting a non-separable bearing are the same as those used for separable bearings, the methods covered here are specifically for non-separable bearings.

If application requirements call for periodic inspections that require mounting and dismounting of the bearings, the ease and methods required for these bearing procedures should be a bearing selection consideration. Bearing mounting and removal is simplified by the use of bearings that have separable races. Bearings such as cylindrical roller bearings, needle roller bearings, and tapered roller bearings have separable races and should be considered for applications requiring frequent inspections and removal of the bearings.

Since bearings with interference fits can be easily damaged during removal, precautions to prevent damage during removal should be taken. Of course, if a bearing is to be discarded, methods such as torch cutting can be used for bearing removal. If the bearing is to be reused or checked for causes of damage, care needs to be taken during removal. To ease removal and avoid damage to the bearing, the proper tools and methods need to be employed.

4.3.1 Mounting and dismounting equipments and tools.

Premature bearing failures are caused by poor fitting, usually using brute force, and being unaware of the availability of the correct mounting tools and methods. Individual installations may require mechanical, heat or hydraulic application methods for correct and efficient mounting. Professional fitting, using specialized tools and techniques, is another positive step towards achieving maximum machine uptime. Reliability variety of bearing installation and removal tools, hydraulic and manual jaw pullers, bearing heaters, etc.

\

Tools/Equipments Uses

Hot Plate Bearing Heater

Mounting

Thread Hydraulic Nut

Mounting and Dismounting

Air-driven hydraulic pumps

Mounting and Dismounting

Standard Jaw Pullers

Dismounting

Induction Heaters

Dismounting

4.3.2 Measuring equipment for bearing installation.

4.3.2.1 Waviness, roundness and form analyzer

Waviness on the bearing components can cause high vibration levels in most applications.  As the amplitude of these waves is as small as some nanometers, you can understand the importance of measuring accuracy and resolution.

Waviness testers allow analysis of the waviness on the components and thus give the production engineer a powerful tool to improve the production process.  Because low noise and vibration of bearings is becoming more important, there is a high demand on the measuring accuracy and resolution.

i. Rotational measuring system with top concentricity precision, with electronics and mechanics combined to perfection

ii. Air-bearing spindle with run out better than 0,02 µm and velocity-proportional evaluation gives you direct indication of the waviness level of the component

iii. The calibration of this equipment is also very important and is performed to an excellent standard.

Figure 4.3.2.1: Waviness, roundness and form analyzer

4.3.2.2 Noise and vibration tester

A noisy application might be caused by wavy bearing components, local defects in the rings and balls or by dirt particles in the bearing.  While basic requirements on a bearing like stiffness, load capacity, speed limit and service life play a critical role in applications, low noise and vibration are becoming even more important.

High tech analysis and measurement such as frequency analysis (FFT) and further advanced analysis pinpoints faults. Spectral masks help to optimize the bearing performance in the particular application.

Figure 4.3.2.2: Noise and vibration tester

4.4.2.3 Dimension measuring machines

Stricter process requirements cause tighter tolerances and higher output, resulting in high demands on the measuring machine capability and time pressure when resetting measuring equipment.  In many cases, the resetting time of the measuring machines already bottlenecks the process where there is still a need for thousands of master parts.

As documented on high precision automation technology, full in-line production control, with minimized resetting times and closed loop post process features, reduce costs and give you flexibility.

Figure 4.4.2.3: Dimension measuring machines

4.4.2.4 Optical inspection

SKF provides products and solutions for a wide variety of optical measurement and optical inspection applications related to bearing manufacture.  Primarily for rotation symmetric components, such as balls, rollers, rings and bearings, industrial optical inspection equipment from SKF keeps costs to a minimum while maximizing your application. In optical systems, the following basic physical principle is involved: "The appearance of the product is different to what we have decided to be acceptable." That appearance is dependent on three factors:

i. condition of the object - colour, roughness, etc. ii. nature of the illumination - white light, coloured light, laser light, etc. iii. properties of the sensors - matrix camera, line camera, single photo-detector, etc.

Figure 4.4.2.4: Optical inspection

4.4.2.5 Non destructive testing

The thorough inspection of components is a way to check that each component is defect free, or complies with certain quality requirements to retain their usability. The various NDT techniques include:

i. ultrasonic inspection ii. Eddy current testing iii. magnetic particle inspection iv. resonant inspection

Figure 4.4.2.5: Non destructive testing

4.4.2.6 Gauges for bearing mounting

When checking features such as tapered seatings, roller set bores or outside diameters of cylindrical roller bearings, conventional measuring methods and instruments are not always suitable.

This gauge is specially designed to meet the measuring needs of cylindrical roller bearings with a tapered bore.  These gauges are also useful for other applications. Ring gauges can be used to check the most common tapered seatings. Measurements can be made quickly and accurately. While a ring gauge can be used only to check a tapered seating for a particular bearing size, the taper gauges can be used for a range of diameters.

To precisely adjust the radial internal clearance or preload when mounting cylindrical roller bearings with tapered bores, it is necessary to accurately measure the roller set bore or outside diameter.

Figure 4.4.2.6: Gauges for bearing mounting

4.3.3 Concept of adjusting clearance during installation.

Selecting the correct bearing internal clearance and determining whether preload is needed for a particular application is critical to obtaining the desired bearing performance.

4.3.3.1 Description of Internal Clearances

Bearing internal clearance is described as being either radial or axial and is the total distance that either the inner or outer ring can be moved in the radial or axial direction while the other ring is held stationary. With only a few exceptions, bearing internal clearance is normally discussed in terms of radial clearance. Matched pairs of angular contact ball bearings are specified in terms of axial internal clearance. Also, when two single row tapered roller bearings are setup opposing each other, the clearance value between the rows is an axial measurement.

Clearance prior to mounting is generally referred to as the original clearance. This initial clearance value is what is provided in the bearing at the time of shipment. After the bearing is fitted on a shaft and into housing, the original clearance is reduced due to contraction or expansion of the rings and is called the residual clearance or mounted clearance. Effective clearance is the residual clearance after taking into account changes from temperature differentials within the bearing.

Operating clearance is defined as the effective clearance with the additional effect of elastic deformations from application loading. Successful bearing performance depends on having the appropriate “operating clearance” to avoid premature bearing damage and reduced fatigue life.

Figure 4.3.3.1: Radial Clearance and Axial Clearance

4.3.3.2 Fit Selection Considerations

As previously pointed out, there are other operating conditions to consider in addition to knowing which ring will be rotating when trying to determine the proper fits to use. The operating conditions that should be considered when determining bearing ring fits are the following:

i. Load characteristicsii. Load magnitudeiii. Temperature effectsiv. Effect on bearing internal clearancesv. Finish of mating surface

vi. Shaft and housing material & section thicknessvii. Mounting design and fixed and float considerations

viii. Bearing type and size

4.3.4 Mounting and dismounting methods classification.

Proper installations of bearing such as a substantial impact shorten its lifecycle. With proper installation of bearing significantly extended for the life of which is a positive impact on maintenance costs. Incorrect installation can cause damages to the bearing and an early failure. Incorrect adaption for the assembly can cause excessive wear and the early damage. To avoid the above mentioned problems it is very important to select appropriate method and proper manner bearing assembly.

4.3.4.1 Mechanical Installation

Mechanical or cold mounting is suitable for small to medium-sized bearings. Use appropriate tools to prevent damage to bearings, other components and not the least injury to persons.

4.3.4.2 Installation using heating

Installation by using heating means based on the induction and it is used in medium and large bearings. By increasing the size of bearings also increase the force required for assembly of the bearing. Due to the size of force are larger bearings very difficult to push the shaft or casing. Pre-heating of the bearing or casing before installation is extremely simplified. In assembly with heated bearing to a temperature that is 80 to 90 ° C above the temperature of the shaft, which mounts bearings.

4.3.4.3 Installation using hydraulic

In this method, there is minimal risk of damage bearing, shaft and other components. Despite the size and weight bearing requires very little effort which is required for installation, while providing a safe working environment without significant risk injury to employees. Principle of the hydraulic assembly technique consists of injecting the thin layer of oil between the bearings and shaft, which greatly reduces friction and allows the bearing assembly with the minimum necessary force. The method is not only useful for bearings, but also in other mechanical components, which the classic method of assembly would have been rather problematic.

4.3.4.4 Mechanical removal

Mechanical removal is suitable for small to medium-sized bearings. Use appropriate tools to prevent damages to bearings, other components and not the least injury to persons. There are several types of downloads, allowing the dismantling of all types of bearings under all conditions:

i. mechanical Downloadsii. hydraulic Downloadsiii. Downloads for blind casings

4.4.4.5 Dismounting with the Heat

Dismantling with the heat is mainly suitable for bearings with close fitting. The use of mechanical downloads could damage the shaft or bearing rings in this case, it requires more power. By using special heaters there are significantly easier to dismantle and reduce the chance of damage to components and body injury. The heaters for dismantling are basically divided into:

i. heated ringsii. induction heaters

4.3.4.6 Dismantling by Oil Injection

Oil injection is a common choice for major dismantling of bearings and other components. Allows disassembly with a substantially lower power and significantly reduce of possibility of damaging bearing, shaft and grounding. The basic principle of the method is injecting oil down the certain viscosity between two surfaces, while between them the pressure generated oil film and differentiate them. This method can reduce the necessary force to dismantle the casing up to 90%.

4.4 Analyze bearing damage.

When a bearing is used under ideal conditions, it should meet or exceed its predicted service life and will eventually be damaged by rolling fatigue. Damage from rolling fatigue can occur prematurely if operating conditions are severe or the wrong bearing was selected for the application. However, as indicated by the following statements, the majority of premature bearing failures are caused by improper lubrication, bearing mounting and handling issues.

If damage is found on a bearing during inspection, it is important to document the bearing’s operation history properly to identify the causes, even if the damage is very small. Also, it is essential to examine not only the bearing but also the shaft, housing and lubricant.

4.4.1 Bearing damage and failure symptoms.

Since there are many different failure modes and damage bearings will exhibit, thefollowing pages will review these and cover possible causes and preventive measures thatcan be taken.

4.4.1.1 Flaking

Flaking is damage where material is removed in flakes from a surface layer of the bearing raceways or rolling elements due to rolling fatigue. This failure mode is generally attributed to the approaching end of bearing service life. However, if flaking occurs at early stages of bearing service life, it is necessary to determine causes and adopt preventive measures.

Figure 4.4.1.1: Flaking

4.4.1.2 Cracking, Chipping

Usually referred to as spalling is a fracture of the running surfaces and subsequent removal of small discrete particles of material.

Figure 4.4.1.2: Cracking, Chipping

4.4.1.3 Brinelling, Nicks

Brinelling is a small surface indentation generated either on the raceway through plastic deformation at the contact point between the raceway and rolling elements, or on the rolling surfaces from insertion of foreign matter, when heavy load is applied while the bearing is stationary or rotating at a low rotation speed. Nicks are those indentations produced directly by rough handling as hammering.

Figure 4.4.1.3: Brinelling, Nicks

4.4.1.4 Pear Skin, Discoloration

Pear skin is damage in which minute Brinell marks cover the entire rolling surface, caused by contamination. This is characterized by loss of luster and a rolling surface that is rough in appearance. In extreme cases, it is accompanied by discoloration due to heat generation. This phenomenon is also commonly called frosting.

Discoloration is damage in which the surface color changes because of staining or heat generation during rotation. Color change caused by rust and corrosion is generally separate from this phenomenon.

Figure 4.4.1.4: Pear Skin, Discoloration

4.4.1.5 Scratch & Scuffing

Scratches are relatively shallow marks generated by sliding contact, in the same direction as the sliding. This is not accompanied by apparent melting of material. Scuffing refers to surface marks, which are partially melted due to higher contact pressure and therefore a greater heat effect. Generally, scuffing may be regarded as an advanced case of scratches.

Figure 4.4.1.5: Scratch & Scuffing

4.4.1.6 Smearing

Smearing is damage in which clusters of minute seizures cover the rolling contact surface. Since smearing is caused by high temperature due to friction, the surface of the material usually melts partially; and the smeared surfaces appear very rough in many cases.

Figure 4.4.1.6: Smearing

4.4.1.7 Rust, Corrosion

Rust is a film of oxides, or hydroxides, or carbonates formed on a metal surface due to chemical reaction. Corrosion is damage in which a metal surface is eroded by acid or alkali solutions through a chemical reaction (electrochemical reaction such as chemical combination and battery formation); resulting in oxidation. It often occurs when sulfur or chloride contained in the lubricant additives is dissolved at high temperature. It can also occur when water becomes entrapped in the lubricant.

Figure 4.4.1.7: Rust, Corrosion

4.4.1.8 Wear

Normally, wear on bearings is observed on sliding contact surfaces such as roller end faces and rib faces, cage pockets, and cage riding lands. However, wear caused by foreign material and corrosion can affect not only sliding surfaces but also rolling surfaces.

Figure 4.4.1.8: Wear

4.4.1.9 Fretting

Fretting occurs to bearings which are subject to vibration while in a stationary condition or which are exposed to slight axial movements. It is characterized by rust-colored wear particles. Fretting damage on the rotating ring is usually a clear indication of an improper fit. Since fretting on the raceways often appears similar to brinelling, it is sometimes called “false brinelling”.

Figure 4.4.1.9: Fretting

4.4.1.10 Cage Damage

Since cages are made of low hardness materials, external pressure and contact with other parts can easily produce dents and distortion. In some cases, these are aggravated and become chipped and cracked. Large chipping and cracks are often accompanied by deformation, which may reduce the accuracy of the cage itself and may prevent the smooth movement of rolling elements. Also, if cage damage is observed, the bearing raceways should be examined for misalignment, as even minor misalignment can cause cage breakage.

Figure 4.4.1.10: Cage Damage

4.4.1.11 Creeping

Creeping is a phenomenon in which bearing rings move relative to the shaft or housing during operation.

Figure 4.4.1.11: Creeping

4.4.1.12 Seizure

Seizure is damage caused by excessive heating in bearings.

Figure 4.4.1.12: Seizure

4.4.2 Observations for preventive maintenance.

4.4.2.1 Flaking

Table 4.4.2.1: Flaking

4.4.2.2 Cracking, Chipping

Table 4.4.2.2: Cracking, Chipping

4.4.2.3 Brinelling, Nicks

Table 4.4.2.3: Brinelling, Nicks

4.4.2.4 Pear Skin, Discoloration

Table4.4.2.4: Pear Skin, Discoloration

4.4.2.4 Scratch & Scuffing

Table4.4.2.4: Scratch & Scuffing

4.4.2.5 Smearing

Table 4.4.2.5: Smearing

4.4.2.6 Rust, Corrosion

Table 4.4.2.6: Rust, Corrosion

4.4.2.7 Wear

Table 4.4.2.7: Wear

4.4.2.8 Fretting

Table 4.4.2.8: Fretting

4.4.2.9 Creeping

Table 4.4.2.9: Creeping

4.4.2.10 Cage Damage

Table 4.4.2.10: Cage Damage

4.4.2.11 Seizure

Table 4.4.2.11: Seizure

4.4.3 Bearing maintenance procedure.

For properly identifying the cause of bearing damage in an application, the following procedure and investigation is recommended:

i. Review service and maintenance records and any other previous data from bearing monitoring equipment.

ii. Prior to bearing removal and inspection, a final noise and temperature check should be performed and recorded.

iii. Create a sheet for documenting bearing and application inspection observations which should include pertinent photos.

iv. Lubricant samples should be taken from bearings and surrounding areas including housing and seals.

v. A sample of new unused bearing lubricant should also be collected.vi. When the bearing is removed from the equipment, step 5 showm in the ‘bearing removal

methods’ section of this book should be followed.vii. If the bearing must be reomved from the shaft by pulling on the outer ring, mark position of

the balls on the inner ring so that the damage that is caused during disassembly can be identified and not mistakenly attributed to an assembly problem.

viii. The machine components surrounding the bearings such as backing shoulders, locknuts, and any sealing devices need to be inspected for damage and wear and then documented on the inspection sheet.

ix. The shaft and housing should be measured for bore and OD sizes, roundness and taper.x. After the bearing has been removed and cleaned, all markings and part numbers should be

recorded. xi. If a bearing is to be returned to the manufacturer for analysis, do not clean the lubricant

from the bearing.xii. The general condition of the bearing should be noted and recorded, with specific

attention to the condition of the rolling elements and raceways.xiii. If further analysis of the bearing damage is required or a metallurgical check may be

needed, a preservative oil should be applied to the bearing prior to repackaging and shipment.

xiv.

Question

1. Identify THREE (3) thermal methods and THREE (3) mechanical methods of mounting bearings.

2. Identify FOUR (4) common causes for bearing failure.

References

5

. 1. Riccardo Manzini, Alberto Regattieri (2010) Maintenance For Industrial Systems,

Springer Dordrecht Heildelberg London, New York, ISBN978-1-84882-574-1

Engr.Mohamed Hamdan Bin Mohamad Ibrahim (PUO)Zaini Bin Ashaari (PMM)

Hajah Norbaya Binti Mhd Simin (POLISAS)

5.1 Clutches and brakes principle.

CLUTCHES AND BRAKES

Learning OutcomesUpon completion of this chapter, students should be able to:-

1. Describe clutches and brakes principle.2. Develop clutches and brakes maintenance procedure

5.1.1 Function of a clutch and brakes.

The function of a clutch is to engage or disengage a machine (or machine component) without starting or stopping the driver. Different types of clutches can also provide the following:

a. Slower, smooth engagement and disengagement under full speed.b. Quick engagement and disengagement.c. Overload protection by limiting the maximum torque loads.d. Prevention of accidental machine reversal.

Brakes are actually clutches with one side locked down so when the clutch/brake engages the rotating shaft stops.

5.1.2 Types of clutches:

a. Mechanicalb. Electricalc. Hydraulic

a. Mechanical clutches

i. Friction Clutches- Widely used in industry (i.e. automotive industry).- Can be actuated or operated manually, pneumatically or hydraulically.- Use a lined metal of fibrous metal mounted between two steel plates as a

means of transferring motion between two mechanical components.- Transferring of motion occur when the separate plates are bought into

contact with each other.- The travel of the friction plates is very small compared to the jaw clutches.- The driven portion of a friction clutch is frequently supported by bearings on

the driving hub.

ii. Jaw Clutches - Usually used on slow speed applications.- Motion for engaging and disengaging the clutch is accomplished with a

shifting arm.- The shifting arm are usually has the fulcrum or pivot point located at one

end of the arm with the operating handle located at the other end.

iii. Centrifugal Clutches- Friction type centrifugal clutches are commonly found in applications where

it is desirable to have either no load starting or protection against overload.- Can also function as couplings or can be mounted directly to V-belt.- In operation, centrifugal clutches start from a disengaged or at rest position.- Centrifugal clutches become positively engaged at no time during operation.

iv. Overrunning Clutches- Also known as one-way clutches.- Frequently used on machine where the driving motor or media requires

protection.

- Prevent overspeeding of the drive by allowing free rotation of the drive component.

- Designed to permit rotation of the driving force in the forward direction only.

- To accomplish this overrunning action, two common type of mechanism are used rollers and sprags.

- Rollers running on flat surface inside round housing while sprags positioned between two circular surfaces. Sprags are irregular or can shaped pieces.

- During operation, sprags are wedged between the inner and outer hubs.

v. Torque Limiting Clutches- Used on any number of different pieces of equipment or also used with

roller chain type coupling.- The driven half of the clutch is always engaged during startup and only slip

when overloaded.

vi. Tooth Clutches- Used pneumatic of hydraulic actuating cylinder to operate.- The mating surface of a tooth clutch is constructed with notches or

serrations.- In operation, the notched surfaces contact each other motion is transmitted

from the driving to the driven halves of the clutch.

b. Hydraulic Clutches

i. Fluid Clutches- Widely used in industry because of their ability to start under heavy

loads and absorb shock loads. - Also used to provide a smooth flow of power to the driven side of a

machine. (Also known as fluid coupling).- The driven half of a fluid coupling is actuated by the hydraulic fluid.- The driving half (pump/impeller) and driven half (turbine) will

rotate at the same speed during operation.

c. Electric Clutches- Used where intermittent motion is required especially to start and

stop the drive motor on short time cycles.- A magnet or coil is mounted on a driven component or machine

while an armature plate is mounted on the driving motor or shaft.- When the two parts are de-energized, no contact or action takes

place between them, even though the motor the motor may be running.

- When an electric current is introduced into the magnet or coil, a magnetic field is set up causing the armature and the coil to draw together.

- This action then couples the two halves electrically and physically causing them to rotate as one piece.

5.1.3 Assemble and dissemble clutch and brake

a. Dissemble clutch and brake

i. Remove the engine from the car.

Note: The pressure plate assembly and clutch disk remain on the flywheel when you remove the engine. The clutch release (throw-out) bearing and related parts stay in the transmission.

ii. If the old pressure plate is to be reused, scribe or paint alignment marks on the pressure plate and the flywheel to ensure proper realignment of the pressure plate during reassembly.

iii. Hold the pressure plate securely and completely, then loosen the pressure plate-to-flywheel bolts by turning each bolt only a little at a time. Work in a criss-cross pattern until all spring pressure is relieved. Then remove the bolts, followed by the pressure plate and the clutch disc.

Caution: The pressure plate is under a great deal of spring pressure. If you work your way around the plate, removing each bolt one at a time, it will warp.

iv. Clean the friction surface on the flywheel and inspect it for wear, cracks, heat checking, grooves, and other obvious defects. Alternating brigt and dull areas indicate a warped plate. A machine shop can machine the surface flat and smooth (highly recommended, regardless of the surface appearance). Light glazing can be removed with medium grit emery cloth.

v. Inspect the diaphragm spring fingers for excessive wear and make sure they are not distorted.

vi. Shake the pressure plate assembly and verify that the diaphragm spring, which should be under tension, does not rattle. If the pressure plate is defective in any way, replace it.

vii. If you will be reinstalling the engine you removed, clean the flywheel and pressure plate friction surfaces with lacquer thinner or acetone.

Caution: DO NOT use oil or grease on these surfaces or on the clutch disk lining. And clean your hands before handling the parts.

viii. Inspect the clutch release (throw-out) bearing. If it feels gritty when you turn it, or if it has been making noise, replace it. Never wash the bearing in solvent since this will remove the factory-installed lubricant. If the bearing is unserviceable, replace per the procedure.

ix. Inspect the lining on the clutch disk for wear. There should be at least 2mm of friction material remaining above the rivet heads.

x. Check the clutch disk for loose rivets, distortion, cracks, broken springs and other obvious damage.

Note: As mentioned above, ordinarily the clutch disk is routinely replaced, so if in doubt the condition, replace it with a new one. If you're planning to re-use the old clutch disk, it's a good idea to check it for run out.

xi. Carefully inspect the splines inside the hub of the clutch disk and the splines on the transmission input shaft. They must not be broken or distorted. Lubricate the splines in the disk hub and the splines on the input shaft with graphite or molybdenum disulfide powder (Rob's last replacement clutch plate came with a tiny tube of special "spline" grease to be smeared sparingly on the splines).

xii. Verify that the clutch disk slides freely on the drive shaft splines without excessive radial play. If the clutch disk is in any way unserviceable, replace it.

Note: You're probably replacing the clutch disk anyway, but if the splines on the input shaft are damaged, you'll have to replace the input shaft as well.

Note: If you are replacing the main oil seal, remove the flywheel at this point and replace the clutch after the flywheel has been reinstalled.

b. Reassemble:

i. Install the flywheel, if removed.

ii. Clean the flywheel and pressure plate friction surfaces with lacquer thinner or acetone.

Caution: DO NOT use oil or grease on these surfaces or on the clutch

disk lining. And clean your hands before handling the parts.

iii. Position the clutch disk and pressure plate against the flywheel with the clutch held in place with an alignment tool (the best alignment tool is an old input shaft, or there is a commercially-available inexpensive one made of plastic).

Note: Clutch Pilot Tool - Using the clutch alignment tool can take a lot of the headache out of installing an engine. Instead of eyeballing to see if the clutch is centered, simply install the clutch alignment tool into clutch disc, and tighten the pressure plate (a turn per bolt, rotate around). The tool will keep the clutch disc centered so the engine goes onto the transmission easier. After you are finished, simply pull the tool out, clean, and save for the next time you need it!

Note: Lacking a centering tool, you can just get down to flywheel height and "eyeball" it. The worst that can happen if it's not exactly centered is that the last inch or so of engine installation might take a little more shoving.

iv. Make SURE the clutch disk is installed properly (most replacement clutch plates will be marked "flywheel side" or something similar. If not marked, install the clutch disk with the damper springs towards the transaxle.

v. If you're reusing the old pressure plate, make sure the marks you made on the pressure plate and the flywheel are matched up.

vi. Install a clutch alignment tool into the center of the clutch disc you intend to use. With the clutch disc on the alignment tool, install the tool into the end of the crankshaft. Make sure that the alignment tool extends through the splined hub and into the needle bearing in the gland nut. Wiggle the tool up-down and/or side-to-side as needed to bottom the tool into the gland nut.

vii. Make sure that the clutch disc is against the flywheel, then install the pressure plate.

viii. Loosely start the six mounting bolts in the flywheel. Tighten them "crosswise", back and forth across the plate to prevent distorting the cover. After all the bolts are snug, torque them first to about 10 ft-lbs and finally to 18 ft-lbs.

ix. Center the clutch disk by ensuring the alignment tool extends through the splined hub and into the needle bearing in the gland nut. Wiggle the tool up-down and/or side-to-side as needed to bottom the tool into the gland nut.

x. Loosely install all of the mounting bolts. Tighten them "crosswise", back and forth across the plate to prevent distorting the cover. After all the bolts are snug, torque them first to about 10 ft-lbs and finally to 18 ft-lbs.

xi. Install the clutch release bearing if removed. Be sure to lubricate the bore of the release bearing and the outer surface of the central guide sleeve with high-temperature grease, and apply multi-purpose grease to the contact areas of the forks on the release

shaft.

xii. Reinstall the engine in accordance with our Engine Installation Procedure.

xiii. Adjust the clutch pedal free play in accordance with our Clutch Cable Adjustment Procedure.

5.2 Clutches and brakes maintenance procedure

5.2.1 Checklist clutches and brakes maintenance, symptoms and record observations for preventive maintenance

i. Improper adjustment of clutch or brake: The clutch or brake may not be fully engaging. Follow the manufacturer’s adjustment procedures.

ii. Oil or contaminant on friction surfaces: Clean or replace the surfaces.

iii. Worn out friction components: Check the components to see if they are within tolerances. Replace them if necessary.

iv. Worn linkage or parts used in engaging clutch or brake: Sometimes adjustment is adequate to compensate for wear. Check for obstruction and corrosion on moving parts. Clean or replace the parts as necessary. Check lubrication, and relubricate if required.

v. Too much torque: This may be because an increased load exceeds design capacity or because of poor initial selection of a clutch or brake. Check the machine to determine if the increased load is temporary or permanent. Repairing or servicing a machine may reduce torque to acceptable levels. If not, the clutch or brake should be replaced with one designed for the increased torque loads required.

vi. High-frequency cycling or high-inertia loads: Generally, these cases of excessive heat can be solved only by changing to a clutch or brake with greater heat-dissipation ability. Sometimes a fan or blower may be used to increase air flow, thus cooling equipment. Shortening the slipping time during start-up can also reduce heat. Less slippage means less heat, but make sure that engagement is not so sudden that severe shock loads are created in the machine. Engaging clutches under the lightest possible start-up loads is always recommended.

With any type of clutch or brake, the following are generally recommended:

i. The clutch or brake should always be the correct size for the application.

ii. Heat dissipation should always be adequate to ensure long life and low maintenance.

iii. Lubrication, if required, should be done on a periodic, regular schedule.

iv. Components should be checked regularly for adjustment and wear.

v. Clutches and brakes should be kept clean and free from debris whenever possible.

6Abd.HafiBin Ismail (PKB)

Aravinthan a/l Yelumalai (PMZA)Mohammad ZainalAkmal Bin Ismail (POLISAS)

6.0 PUMPS,VALVESANDCOMPRESSOR

6.1 Understand pumps concepts.Irrigation pumps lift water from an existing source, such as surface or groundwater to a higher level.They have to overcome friction losses during transport of the water and provide pressure for sprinkler and drip irrigationIrrigation pumps are mechanical devices which use energy from electrical or combustion motors to increase the potential and (or) kinetic energy of the irrigation water. Pumps are used in irrigation systems to impart a head to the water so it may be distributed to different locations on the farm and used effectively in application systems.The key requirement in pump selection and design of pump systems for typical irrigation installations is that there is a correspondence between the requirements of the irrigation system and the maximum operating efficiency of the pump

PUMPS,VALVESANDCOMPRESSORLearning Outcomes

Upon completion of this chapter, students should be able to:-1. Understandpumpsconcepts.2. Understand valve concepts3. Understandcompressor concepts.

6.1.1 List application of pumps.Pumps are used throughout society for a variety of purposes. Early applications includes the use of the windmill or watermill to pump water. Today, the pump is used for irrigation, water supply, gasoline supply, air conditioning systems, refrigeration (usually called a compressor), chemical movement, sewage movement, flood control, marine services, etc.

6.1.2 Classify types of pumps based on it’s principle.iv. Positive displacementv. Rotor dynamic

i. A Positive Displacement Pump has an expanding cavity on the suction side of the pump and a decreasing cavity on the discharge side. Liquid is allowed to flow into the pump as the cavity on the suction side expands and the liquid is forced out of the discharge as the cavity collapses. This principle applies to all types of Positive Displacement Pumps whether the pump is a rotary lobe, gear within a gear, piston, diaphragm, screw, progressing cavity, etc.

There are three main classifications of Positive Displacement Pumps a. Rotary Positive Displacement Pumpb. Reciprocating Positive Displacement

ii. Rotor dynamic pumps are kinetic machines in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor. The most common types of rotor dynamic pumps are centrifugal (radial), mixed flow, and axial flow pumps.

These pumps are based on bladed impellors which rotate within the fluid to impart a tangential acceleration to the fluid and a consequent increase in the energy of the fluid.   The purpose of the pump is to convert this energy into pressure energy of the fluid to be used in the associated piping system.  Centrifugal pumps use bladed impellers with essentially radial outlet to transfer rotational mechanical energy to the fluid primarily by increasing the fluid kinetic energy (angular momentum) and also increasing potential energy (static pressure). Kinetic energy is then converted into usable pressure energy in the discharge collector.

There are three main classifications of rotodynamic pumps c. Radial Flow (Centrifugal Pumps)d. Mixed Flow (Screw )Pumpse. Axial Flow (Propeller) Pumps

6.1.3

Assembleanddisassemblepumpasapractical.Asaexamplescomponentscanbeuseiscentrifugal pump.

Disassembly pump

1. Unloose the screws of fan cover andremove it.

2. Remove the fan by means of ascrewdriver.

3. Remove the plugs from the pump casing

4. Using a bench vice lock the pump fromthe motor shaft then release the preloadscrews as shown in the picture.

5. Remove the motor holder.

6.1.4 Developed check list pumps maintenance, symptoms and record observations for preventive maintenance.

Pump Maintenance Concept Poor maintenance can cause undue wear and tear of fast moving parts, and premature failure of the equipment. Such premature failure or breakdown causes immense hardship to the consumers and staff, and avoidable increase in repair cost. The shortcomings in maintenance can also result in increase in hydraulic and power losses and low efficiency. Inefficient running of the pump increases burden of power cost. Importance of preventive maintenance, therefore, need not be overstressed.

Appropriate maintenance schedule and procedure need to be prescribed for all electrical and mechanical equipment based on manufacturers’ recommendations, characteristics of the equipment, site and environment conditions i.e. temperature, humidity, dust condition, etc. The maintenance schedule also needs to be reviewed and revised in the light of experience and analysis of failures and breakdown at the pumping station. The preventive maintenance schedule shall detail the maintenance to be carried out at regular intervals i.e. daily, monthly, quarterly, half yearly, annually etc. or operation hours. The schedule shall also include inspections and tests to be performed at appropriate interval or periodicity.

Check List Pump Maintenance, Symptoms and Record Observation For Preventive Maintenance

(a) Routine observations of irregularities

The pump operator should be watchful and should take appropriate action on any irregularity noticed in the operation of the pumps. Particular attention should be paid to following irregularities.

i. Changes in sound of running pump and motorii. Abrupt changes in bearing temperature.iii. Oil leakage from bearingsiv. Leakage from stuffing box or mechanical sealv. Changes in voltagevi. Changes in currentvii. Changes in vacuum gauge and pressure gauge readingsviii. Sparks or leakage current in motor, starter, switch-gears, cable etc.ix. Overheating of motor, starter, switch gear, cable etc.

(b) Record of operations and observations

A log book should be maintained to record the hourly observations, which should cover the following items.

i. Timings when the pumps are started operated and stopped during 24 hours.

ii. Voltage in all three phases.iii. Current drawn by each pump-motor set and total current drawn at the

installation.iv. Frequency.v. Readings of vacuum and pressure gauges.vi. Motor winding temperature.vii. Bearing temperature for pump and motor.viii. Water level in intake/sump.ix. Flow meter reading.x. Any specific problem or event in the pumping installation or pumping

system (burst in pipeline, tripping or fault, power failure).

Pump Maintenance ProcedureDaily Maintenance

• Clean the pump, motor and other accessories.• Check coupling bushes/rubber spider.• Check stuffing box, gland etc

Monthly Maintenance

i. Check free movement of the gland of the stuffing box, check gland packing and replace if necessary.

ii. Clean and apply oil to the gland bolts.iii. Inspect the mechanical seal for wear and replacement if necessary.iv. Check condition of bearing oil and replace or top up if necessary.

Quarterly Maintenance

i. Check alignment of the pump and the drive. The pump and motor shall be decoupled while correcting alignment, and both pump and motor shafts shall be pushed to either side to eliminate effect of end play in bearings.

ii. Clean oil lubricated bearings and replenish with fresh oil. If bearings are grease lubricated, the condition of the grease should be checked and replaced/replenished to the correct quantity. An anti-friction bearing should have its housing so packed with grease that the void space in the bearing housing should be between one third to half. A fully packed housing will overheat the bearing and will result in reduction of life of the bearing.

iii. Tighten the foundation bolts and holding down bolts of pump and motor mounting on base plate or frame.

iv. Check vibration level with instruments if available; otherwise by observation.v. Clean flow indicator, other instruments and appurtenances in the pump

house.

6.2 Understand valve concept.

A valve is a device regulates directs or controls the flow of a fluid (gases, liquids, fluidized solids) by opening, closing.

6.2.1 Application of valves

Gas system Crude oil industry Refinery plant

6.2.2 Classify types of valves.

Common valve type in usage.

Ball valve Butterfly valve Gate valve Globe valve

Figure 6.2.1 Ball valve

Figure 6.2.2 Butterfly valve

Figure 6.2.3 Gate valve

Figure 6.2.4.Globe Valve

Valves can be categorized into the following basic types:

Ball valve, for on/off control without pressure drop, and ideal for quick shut-off, since a 90° turn offers complete shut-off angle, compared to multiple turns required on most manual valves.

Butterfly valve, for flow regulation in large pipe diameters.

Gate valve, mainly for on/off control, with low pressure drop.

Globe valve, good for regulating flow.

Characteristic of valve.

Ball Valve

Ball valves are devices use a ball to stop and start the flow of fluid. As the valve stem turns to the open position, the ball rotates to a point where part or the entire hole machined through the ball is in line with the valve-body inlet and outlet. This allows fluid to pass through the valve. Ball rotates so that the hole is perpendicular to the flow path, the flow stops. Most ball valves are quick-acting and require a 90-degree turn of the actuator lever to fully open or close the valve.

Figure 6.2.5 Butterfly valve function.

The butterfly valve (figure 6.2.6) has a disk that rotates about a central shaft or stem. When the valve is closed, the disk face is across the pipe and blocks the flow. Butterfly valve seat consist of a bonded resilient liner, a mechanically fastened resilient liner, an insert-type reinforced resilient liner, or an integral metal seat with an O-ring inserted around the edge of the disk.As shown in Figure 13.4, both the full open and the throttled positions permit almost unrestricted flow. Therefore, this valve does not induce turbulent flow in the partially closed position. While the design does not permit exact flow-control capabilities, a butterfly valve can be used for throttling flow through the valve. In addition, these valves have the lowest pressure drop of all the conventional types.

Figure 6.2.6.Butterfly valve function.

Gate valve

Gate valves are used straight line, laminar fluid flow, and minimum restrictions are needed. These valves use a wedge-shaped sliding plate in the valve body to stop, throttle, or permit full flow of fluids through the valve. When the valve is wide open, the gate is completely inside the valve bonnet. This leaves the flow passage through the valve fully open with no flow restrictions, allowing little or no pressure drop through the valve. Gate valves are not suitable for throttling the flow volume unless specifically authorized for this application by the manufacturer. They generally are not suitable because the flow of fluid through a partially open gate can cause extensive damage to the valve.

Figure 6.2.7.Gate valve function.

Globe valve

A disk attached to the valve stem controls flow in a globe valve. Turning the valve stem until the disk is seated closes the valve. The edge of the disk and the seat are very accurately machined to provide a tight seal. It is important for globe valves to be installed with the pressure against the disk face to protect the stem packing from system pressure when the valve is shut. While type of valve is commonly used in the fully open or fully closed position, it also may be used for throttling.

Figure 6.2.8 Globe valve function

6.2.3 Determine valve maintenance concept.

Ball Valve

There are specific cleaning agents that should be used with the valve parts that are made of plastic, rubber, and metal. The appropriate cleaning agent should be used to avoid reaction of the cleanser with the parts. This can prevent any damages that can be brought by corrosive reactions. Cleansing sprays made of gas perfectly works for metal parts where gas is the working medium. Alcohol or water or a mixture of the two can be applied on non-metal parts. However, there are manufactured cleansers that are especially formulated for valve parts.

Butterfly Valve

Following proper directions and instructions is and will always be a nice thing to do, even in installing a butterfly valve inside the house. No kidding. This valve is widely used in day-to-day life such as in the carburettor of a car. These valves are mainly used in controlling a certain object, in the case of a carburettor, and then the entrance of air in the car is being decreased or increased through the use of the valve. Simply put, this is used to regulate the flow which in this case, is the air. Due to this high end function, proper and constant maintenance of this valve is a must. This valve is operated similar to that of a ball valve.

Gate valve

The proper maintenance of a gate valve, or any valve for that matter, is important in ensuring that it will last for many years and work as efficiently as it should. Thinking that it can simply be installed and left alone afterwards is the beginning of the end since the time will definitely come that the valve will either have to be repaired or totally replaced due to lack of maintenance. So, if you want to spare yourself a few headaches and several dollars in repair or replacement costs, learn how to maintain your gate valves effectively.

6.2.4 Developed check list valve maintenance symptoms and record observation for preventive maintenance.

Control/Shut-OffValve- Inspection Form

G eneralInf ormat ion :

DateofSiteVisit: UnitNo._

PlantName:

Source/sofdata:

ValveManufacturer: _Age ofValve: ___

SizeofValve: SizeofPenstock

SystemPressure(PSI):

Control/Shut-OffValveDescription:_ __

Maintenance History/MajorRepairsDescription:

Co nt rol/Shut -Of fValv e:

ValveManufacturer/Model:

RatedOperatingPressure:

Additionspecificationdata:

Valv e Op er ato r:

Make:_ Model: _

Additionspecificationdata:

4

Control/Shut-OffValveCheck List

Topic Yes No N/A Comments/Details

Maintenance&MajorRepairHistoryArethereplantpreventivemaintenanceprocedures for theControl/Shut-off Valve? Aretheyroutinelycarriedout?

Has therebeen anyvalveand/orpenstockrepair?

Has theValvebeenrebuilt?

Has thevalveoperator beenrebuilt?

Ifpartsof valverequire lubrication,arethererecordsoflubricantapplication?

Haveallplantrecords regardingvalverepairs,operatingconditions, etc. beenrequested/gathered?

5

Control/Shut-OffValveCheck List- Continued

Topic Yes No N/A Comments/Details

Equipment ConditionAssessment

Whatisconditionof theexteriorofthevalve?

CantheinterioroftheValvebeaccessed?

Whatisthe conditionoftheinteriorof thevalve?

Whatisthe conditionofthe valveoperator?

Aredifferentialpressureindicatorsortransmitterspresent?

Aredifferentialpressureindicatorsortransmittersoperational?

Control/Shut-OffValveCheck List- Continued

Topic Yes No N/A Comments/Details

Equipment ConditionAssessment-Continued

Isthereavalvepositionindicator?

Doesthevalvepositionindicatorfunctioncorrectly? Localand/or remote?

Havevalvemalfunctions been notedasthe causeof unit outagesor unitderatings? If so, howmanymegawatthourslost(MWHL)havebeenattributedtovalves?

Doesthevalvehavepackingleaks?

Doesthevalvehaveflange gasketleaks?

Isthevalveinsulated?Ifso, doestheinsulationcontainasbestos fiber?

Control/ShutoffValveDataCollectionSheetTopic DataInput

Symptom and corrective action for ball valve.

SYMPTOMS REASON ACTION

Symptom and corrective action for butterfly valve .

SYMPTOMS REASON ACTION

Symptom and corrective action for globe valve .

SYMPTOMS REASON ACTION

6.3 Compressor Concept

Introduction

This machine is broadly use in our everyday live where we can find them in our homes and workplaces, and in almost any form of transportation we might use. Compressors serve in refrigeration, engines, chemical processes, gas transmission, manufacturing, and in just about every place where there is a need to move or compress gas.

Compressor in general

In general compressors are machines that are used to compress air or gas. It also a machine that handling fluid that capable efficiently transferring energy to the fluid medium so that it can be delivered in large quantities at desired pressure condition. The working principles are the same with pump working principle where both can also transfer it through a pipe. It also is mechanical devices which convert the air into energy, this energy can then be used to run machinery and perform various functions. Compression is achieved through the reduction of the volume that the gas (or air) occupies. As a side effect of the minimization of volume, the temperature of air or gas increases. The higher the compression ratio, the higher the temperature tends to rise.

6.3.1 List of Application

Compressors are widely used by various types of industries and home appliance that depend on the power of compressed gas or fluid to power manufacturing processes in the industries. List the application of compressor such as:-

a) Air conditioners for car and home b) Air pumps c) Home and industrial refrigeration d) High pressure car washes e) Hydraulic compressors for industrial machines f) Air compressors for industrial manufacturingg) Chemical/petrochemical plantsh) ethylene plantsi) Gas lift/gas gatheringj) Gas injection/transportk) LNG facilitiesl) Gas to liquidsm) Ammonia plantsn) Power generator

ries

6.3.2 Type of compressor

It can be divided into two main categories:-i. Dynamic

ii. Positive displacement

Figure 6.3.1 type of compressor

6.3.3 Principle and Characteristic of Compressor

i) Dynamic

This type of compressors uses the phenomenon of velocity to generate energy. It happens by creating high speed energy through a rapidly moving piece. This fast moving piece then propels the basic unit of the air compressor to generate power which is then used for mechanical purposes. The dynamic compressor is characterized by rotating impeller to add velocity and pressure to fluid. Compare to positive displacement type compressor, dynamic compressor are much smaller in size and produce much less vibration. Although the dynamic air compressors are very useful they are not as common as the positive displacement compressors and their use is mostly restricted to various industries and is not used at homes. It is widely used in chemical and petroleum refinery industry for specifies services. They are also used in other industries such

COMPRESSOR

Dynamic Centrifugal

Positive Displacement

Rotary

Reciprocating

as the iron and steel industry, pipeline booster, and on offshore platforms for reinjection compressors.

a) Centrifugal Compressor

Figure 6.3.2 centrifugal pumps

A centrifugal compressor is a ‘‘dynamic’’ type of compressor. It has a continuous flow of fluid which receives energy from integral shaft impellers. In a centrifugal compressor the mechanical energy is increased by centrifugal action. The gas enters the suction eye of a high speed rotary element called the impeller which carries radial vanes integrally cast in it. As the impeller rotates, the blades of the impeller force the gas outward from the center the impeller to the outer rim of impeller, the increase in velocity of the gas creates a flow pressure area at the eye of the impeller. The gas at the outer rim of the impeller is forced in to a passage way called a diffuser where the velocity decreases in the pressure of the gas. The maximum pressure rise for centrifugal compressor mostly depends on the rotational speed (rpm) of the impeller and the impeller diameter. But the maximum permissible speed is limited by the strength of the structural materials of the blade and the sonic velocity of fluid and it will leads into limitation for the maximum achievable pressure rise.

Advantages

a) Reliableb) Compactc) Robustd) High reliability, eliminating the need for multiple compressors and installed standby

capacity. e) For the same operating conditions, machine prices are lower for high volume flow rates. f) Less plot area for installation for a given flow rate.g) Machine is small and light weight with respect to its flow rate capacity.h) Installation costs are lower due to smaller sizei) Low total maintenance costsj) When a turbine is selected as a driver, the centrifugal compressor's speed level allows

direct drive thereby minimizing equipment cost, reducing power requirements, and increasing unit reliability. 

k) Flow control is simple, continuous, and efficient over a relatively wide flow range. l) No lube oil contamination of process gas.m) Absence of any pressure pulsation above surge point.n) Can reach pressure up to 1200 psi.o) Completely package for plant or instrument air up through 500 hp.p) Does not require special foundations

Disadvantages 

a) Lower efficiency than most positive displacement types for the same flow rate and pressure ratio. 

b) Due to recycle not efficient below the surge point.c) Very sensitive to changes in gas properties, especially molecular weight d) Not effective for low molecular weight gases. The pressure ratio capability per stage is

low, tending to require a large number of machine stages, hence mechanical complexity.e) High initial costf) Complicated monitoring and control systemsg) High rotational speed require special bearings and sophisticated vibration and clearance

monitoringh) Specialized maintenance considerations

ii) Positive Displacement Compressor

Positive displacement compressors types deliver a fixed volume of air at high pressures condition. It can be divided into two types which are rotary compressors and reciprocating compressors. In this type of compressor a certain inlet volume of gas is confined in a given space and subsequently compressed by reducing this confined space or volume. At this elevated pressure, the gas is expelled into discharge piping or vessel system.

a) Rotary Compressor

Figure 6.3.3 Rotary Compressor

Rotary compressor is a group of positive displacement machines that has a central, spinning rotor and a number of vanes. It also generally classified as screw compressor, vane type compressor, and lobe and scroll compressor. The difference between each type is their rotating device.

This compressor gains the pressurizing ability from a spinning component. These types of compressor are compact, relatively inexpensive, and require a minimum of operating attention and maintenance. The compressor increased the pressure of the gas by trapping it between vanes

which reduce the volume when the impeller rotates around an axis eccentric to the casing as show in the figure 6.3.4 below:

Figure 6.3.4 Rotary Compressor Gas Compressing Principle

The volume can be varied by changing the speed or by bypassing or wasting some of the capacity of the machine. The discharge pressure will can be control with the resistance on the discharge side of the system.

Advantages

a) Simple designb) Low to medium initial and maintenance costc) Two-stages design provide good efficienciesd) Easy to installe) Few moving parts

Disadvantages

a) High rotational speedb) Shorter life expectancy than any other designsc) Single-stage designs have lower efficiencyd) Difficulty with dirty environment

b) Reciprocating compressor

Figure 6.3.5 Reciprocating Compressor

The reciprocating or also called as piston compressor, is another type of common positive displacement compressor. It uses the movement of a piston within a cylinder to increase the pressure of the gas from lower pressure level to higher pressure level. It can be considered as single acting, when the compressing is accomplished using only one side of the piston, or double acting when it is using both sides of the piston. This machine is used when high-pressure head is required at a low flow. Generally, the compression ratio will determine the maximum allowable discharge-gas temperature. It can be single-stage or multistage compressor. Typical compression ratios for the compressor are about 3 per stage in order control the discharge temperatures from 300of to 350°f. Some reciprocating compressors have as many as six stages that can provide a total compression ratio over 300.

Figure 6.3.6 Reciprocating Compressor Working Principle

As shown in the figure 1.6 above the gas enters the suction manifold into the cylinder cause by the vacuum condition that is created inside the cylinder as the piston moves downward. When the piston reaches its bottom position it begins to move upward. So the intake valve closes and trapping the gas fluid inside the cylinder. After that the piston continues to move upward and compresses the gas and the pressure will increase. The high pressure in the cylinder pushes the piston downward cause by the higher pressure that occurs in the cylinder. As the piston is reaching near the bottom of the cylinder, the exhaust valve opens and releases high pressure gas fluid.

Advantages

a) Simple design, easy to install b) Lower initial cost c) Large range of horsepower d) Special machines can reach extremely high pressuree) Two stages models offer the highest efficiency

Disadvantages

a) Higher maintenance costb) Many moving partsc) Potential for vibration problemsd) Foundation may be required depending on sizee) Many are not designed to run at full capacity

6.3.4 CompressorMaintenanceConcept

In order to maintain an air compressor system it requires well care of the equipment, paying attention to changes and trends, and responding promptly to maintain operating reliability and efficiency. To assure the maximum performance and service life of your compressor, a routine maintenance schedule should be developed. Proper maintenance requires daily, weekly, monthly, quarterly, semi-annual, and annual procedures. Monitoring operating conditions on a daily or shift change base is good practice. It allows the operators to become familiar with a smooth running machine which will lead to early detection of potential problems. Excellent maintenance is the key to good reliability of a compressed air system; reduced energy costs are an important and measurable by product. The benefits of good maintenance far outweigh the costs and efforts involved. Good maintenance can save time, reduce operating costs, and improve plant manufacturing efficiency and product quality

Just as with any other type of machinery, compressors are subject to operational changes from environmental conditions, wear, or neglect. A plugged condensate drain, unusual noises, temperature or vibration increases, discolored oil, and/or fluid leaks are some examples of operational changes that may signal beginning of potential problems. Recognizing any changes in operation and appropriately responding to those changes can prevent undesirable consequences such as unscheduled shutdown and/or the expense of unanticipated repairs.

6.3.5 Maintenance Check List, Compressors Failure Symptom and Preventive Maintenance Observation

Maintenance Check List

Daily inspection

A daily inspection takes only a short time, but it will allow the operator to develop a definite sense of the appearance, sounds, and other operating conditions of a smoothly performing compressor. Any changes can be investigated and be given attention before major problems develop.

Daily operator inspection checklistWarning: exercise care when in the vicinity of hot surfaces, pressurized air, and high voltages.Procedures accompanied by the alert symbol (!) Require special precautions as indicated.()

Operating data log

Operating parameters recorded and within specificationsSetpoints recordedGearcase(high surface temperatures)External surfaces wiped cleanNo unusual noise or vibrationsNo oil leaksNo water leaksNo frayed or worn electrical cablesIntercoolers and aftercooler(pressurized air, high surface temperatures)External surfaces wiped cleanCondensate drains functioning properlyNo cooling water leaksNo air leaksLubrication system (high voltages at heater, pump motor)External surfaces wiped cleanProper oil level in oil reservoirProper oil colorNo mist from ejector systemNo oil cooler water leaksNo oil leaksNo frayed or worn electrical cablesCompressor drive motor (inspect visually only—high voltages, temperatures)External surfaces wiped cleanProperly ventilatedNo erratic or noisy operationNo frayed or worn electrical cablesInspected in accordance with manufacturer’s recommendations

Table 6.3.1 Example of Daily Operator Inspection Checklist

Scheduled maintenance

Table 1-2 below lists suggested intervals for prescribed scheduled maintenance procedures such as those involving filters, lubrication, and other inspections and/or adjustments. Bear in mind, however, that these intervals may vary with operating conditions and/or actual hours of machine operation. Some items may require attention more or less frequently as circumstances dictate.

Scheduled maintenance procedures

()

Weekly:(or after about 150 hours of operation)Inlet air filter elements inspected, replaced if requiredOil reservoir venting system filter elements inspected, replaced if required

Bypass valve filter checked (if supplied)Every six months:(or after about 4000 hours of operation)Oil reservoir venting system filter element changedOil system filter element changedLubrication system oil tested and changed if requiredCoolant chemically testedBypass valve lubricated (if required – check instructions)Inlet guide vane assembly drive screw lubricatedMain drive coupling inspected and lubricated.Drive motor ball bearings lubricated with recommended grease.Oil pump motor lubricated with recommended greaseDischarge air check valve inspected

Table 6.3.2 Example of Scheduled Maintenance Checklist

Professional inspection

A substantial part of any good preventative maintenance program also involves professional inspection and replacement of common maintenance components after an established interval. Such in-depth inspection is particularly important when an unscheduled and/or long-term shutdown would seriously affect production. Table 1.3 below lists the items which require a professional service inspection whenever environmental or operational conditions dictate. Contact a authorized service representative for those procedures and for professional advice.

Service inspection checklistTo be performed with a manufacturer authorized representative:()

Gearcase

Impellers, inlets, and diffusers cleanedImpellers, inlets, and diffusers inspectedGearing visually checkedGearing backlash clearances measuredAxial pinion float checkedClearances between impellers and inlets checkedIntercoolers and aftercoolerBundle tubes inspected, cleaned if requiredBundle fins inspected, cleaned if requiredCooler cavities cleaned and inspectedLubrication systemPiping connections checked for leaksOil visually inspectedOil cooler inspectedFiltersAll filter elements inspected

Control panel

Inspected for proper operationControl valves

Inlet guide vane inspectedBypass valve inspectedDischarge air check valve inspectedDrive motor

Main drive coupling inspected and re-greasedMotor inspected in accordance with manufacturer’s instructions

Table 6.3.3 Example of Service Inspection Checklist by Professional

Compressors Failure Symptom

For compressor itself there are several common failure symptoms that must be pay attention in order to detect the problems, so that correction step can be done to prevent severe damage to occur. In the table below show the common symptom, cause and correction step for each symptom.

SYMPTOM CAUSE CORRECTION

High Discharge

Temperature

Sump lubricant low. Fill lubricant.

Clogged or varnished heat exchanger/oil cooler.

Inspect lubricant lines for blocks.

Analyze lubricant. If varnish is present, flush with

cleaner.Faulty thermal by-pass valve. Rebuild or replace by-pass valve.Restriction of heat exchanger air flow.

Remove restrictions.

Insufficient air circulation at oil cooler.

Check location and make sure there is no restriction of cool fresh air.

Plugged oil filter element. Replace oil filter elementsPremature Lubricant

Breakdown

Compressor operating too hot. See corrections for high discharge temperature.

Chemically active gases present. Review plant/operations/make-up air.

Analyze oil and correct inlet air source as needed.

Improper receiver condensate • Periodically drain receiver

draining. condensate.• Inspect auto-drains, drain lines and valves.

Mixing incompatible lubricants. • Drain, replace and analyze oil.• Flush compressor with cleaner.

Frequent Separator Plug-Up / Collapse

Incompatible oil in compressor. Review and analyze oil. Replace with proper lubricant.

Minimum pressure valve sticking. Rebuild or replace valve.Ruptured intake air path filter. Inspect inlet filter and air path,

checking for voids. Replace and repair as needed.

Decreased Discharge Pressure

Excessive air demand. Check plant air demand and inspect plant for air leaks.

Service valve open. Close valve.Leaky service line. Fix leaks.Plugged inlet air filter. Clean or replace filter. Inlet valve partially closed. Check inlet valve assembly and

rebuild as needed.

Failure To Start

Safety shut-down tripped. Re-set compressor safety.Disconnected main switch. Check switch and verify that power

is ON.Power failure. Check power supply.

High Power Consumption

Plugged air/oil separator Change separator element.Wrong air pressure setting. Adjust setting.Obstructed after cooler. Clean after cooler.Plugged inlet air filter. Inspect and replace as needed.Lubricant viscosity issues. Test and replace oil as needed.

Excessive Lubricant

Consumption

Overfilled lubricant sump. Drain receiver to proper levelBroken lubricant line .Replace lubricant line.High compressor discharge temperature.

• Inspect and clean coolers.• Inspect temperature control valve.

• Improperly positioned lubricant return scavenges line.

• Plugged scavenge line.• Check scavenges line connections.• Make sure that scavenge line is cut at 45° angle, reaches the bottom of the separator and isn’t blocked.

Table 6.3.4 Common Failure System, Cause and Correction Step. Preventive Maintenance Observation

Preventive maintenance is very important in order to maintain the compressor in their best condition. Listed below is the general preventive maintenance that can be done in order to maintain the compressor to work in their best condition.

1. FoundationAnnual. Examine concrete for cracks and spalling.

2. FrameAnnual. Examine metal for corrosion and cracks. Clean and paint if required.

3. Compressor DriveWeekly. Check v-belts for slippage, chains for looseness, and shaft couplings for excessive run out or vibration. Dress or tighten v-belts if required. Tighten coupling bolts and lubricate coupling if required.Annual. Check v-belts for signs of wear or aging and replace as needed. Check shaft run out of direct coupled machines with dial indicator and check shaft alignment if run out is excessive.

4. Cooling SystemWeekly. Check flow of water or coolant through compressor and after cooler.Check for accumulation of dirt and lint on cooling fins of air-cooled compressors and radiators or water-cooled compressors.Annual. Check for corrosion and scale buildup and clean or flush as required.Thoroughly clean cooling fins of air-cooled compressors and radiators ofwater-cooled compressors.

5. Air IntakeWeekly. Check condition of filter and intake for obstructions. Replace filter as required.

6. Piping and ValvesAnnual. Check piping for corrosion. Clean and repaint or replace piping as required. Repack and reseat valves as required.

7. AftercoolersNot Scheduled. Check for leaks and for adequate water flow. Disassemble and check for internal corrosion and scale buildup. Clean as required.

8. SeparatorsNot Scheduled. Check for leaks. Disassemble and check for corrosion and scale buildup. Clean as required.

9. TrapsWeekly. Operate manual drains.Annual. Check automatic traps for leaks and proper operation. Clean strainer and check for corrosion or scale buildup.

10. Dryers

Annual. Replace dryer elements as required on deliquescent dryers. Check operation of refrigerated and desiccant types.

11. Pressure Regulating ValvesAnnual. Check operation and verify that regulating valves are providing correct pressure downstream from valve.

12. Pressure Relief ValvesAnnual. Verify operation and setting. Check for signs of leaking, rust or corrosion, deposits, or mineral buildup. Perform operational test of relief valve either in service or remove and perform test on test stand. If a valve is found to be not functioning properly, the system immediately should be taken out of service until the valve can be repaired or a new valve can be installed. The relief valve setting should not be changed by plant personnel. The setting of a pressure relief valve can only be certified by an accredited repair facility.

13. Receiver Tanks and Other Pressure VesselsWeekly. On air receiver tanks, open the receiver drain valve and blow down until water is removed from tank. Check for leaks on all pressure vessels. Annual. Make thorough inspection of exterior of the tank, paying close attention to joints, seams, and fittings. The inspection should be performed by a qualified inspector.

14. GaugesWeekly. Check operation of gauge. Look for loose or stuck pointer. If there is any doubt about the accuracy of gauge, remove and check calibration or replace with new gauge. Biannual. Remove gauge and calibrate. Make any necessary repairs or replace with new gauge if gauge is not repairable.

15. Pressure and Temperature SwitchesMonthly. See that pressure switches cut in and out at proper pressures. Check setting of temperature switches. Annual. Check switch calibration and set points.

16. UnloaderMonthly. Check that compressor is not being loaded until operating speed is reached in starting and that it unloads at the proper pressure. Annual. Inspect valves and air lines for leaks and valves for proper seating. Lap valves if required. Examine solenoid for deteriorated insulation or loose connections.

17. BearingsWeekly. Check antifriction bearing for excessive vibration or noise and schedule replacement as required. Check for adequate lubrication. Not Scheduled. Disassemble compressor and inspect condition of all bushings and babbitt-lined bearings. Repair or replace as required.

REFERENCE

1. R. Keith Mobley (2008). “Maintenance Engineering Handbook 7th.Ed.”McGraw-Hill, USA. ISBN 978-0-07-154646-1

2. R. Keith Mobley (2004). “Maintenance Fundamentals.” Elsevier Butterworth-Heinemann, Oxford, U.K. ISBN 0-07-026005-2

3. Hanlon P.C., ed. (2001). “Compressor Handbook” McGraw Hill, Two Penn Plaza, New York. ISBN 0-07-026005-2

4. Ling. A. L. and ViskaMulyandasari (2011) .“Compressor Selection and Sizing (Engineering Design Guidelines)” KLM Technology Group, Johor Bharu.

5. Roger Cline, John Germann and Bill McStraw(2009). “Maintenance Scheduling for Mechanical Equipment” Facilities Instructions, Standards and Techniques, Volume 4-1A – Revised 2009, U.S. Department of the Interior, Bureau of Reclamation, Denver, Colorado.

6. “Air Compressor Maintenance.” Industrial Power Air, Muskego, WI, USA.7. Glenn K. Moore. (2009) “Field Service Notes (Why Compressors Fail)”, Danfoss Ltd.

Denmark.8. R. Keith Mobley (2008). “Maintenance Engineering Handbook 7th.Ed.”McGraw-Hill,

USA. ISBN 978-0-07-154646-19. R. Keith Mobley (2004). “Maintenance Fundamentals.” Elsevier Butterworth-

Heinemann, Oxford, U.K. ISBN 0-07-026005-2

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