Cau hoi thi SQVH

test 1

I. Read and translate the following passage into Vietnamese.

The cylinder block is made of cast iron and does not admit welding, so that the most effective system of repair (especially in the formation of cracks) is the cold repair method. In this system, the cast material is not heated, so that there are no expansions nor any change in the molecular(ph ân t ử) structure of the material. The inside of the block should be inspected with the liner disassembled(đít sơ sem bồ), any encrustations( en kớt x ây s ừn) are to be cleaned and any subsequent oxidation and corrosion on the block and the liner itself are to be noted. The block cooling water circulates on the outside of the liner, bathing(b ây thing) the inside of the block. Therefore, in removing a liner to inspect the inside, it is appropriate(ơ p ờ r âu pi ết) to drain the block completely of water, thereby preventing water from dropping into the casing. When a piston is removed, the level of water in the cylinder block must be lowered to a few centimetres below the top level of the liner, and the water leader of the expansion tank must also be shut to prevent water from falling from the head when it is removed.

II. Base on the above passage to answer the teachers’ questions.III. Off-hand translation.

IV. Free talk about everyday life.test 2

I. Read and translate the following passage into VietnameseIntake and Exhaust Valves

When the engine is using fuel oil, the temperature of the exhaust gases is higher than when it uses gas oil. Because of this, and because of impurities in the gases, exhaust valves and their seats in fuel oil engines are cooled by the engine water, and are also built of a special material that can withstand the action of the exhaust gases for a longer period.

When there is a leak in an intake or exhaust valve, it is due to irregularities in the closing area (ring and cone(c ôn)). If these irregularities are minor, valve and seat can be repaired on board using a lathe(lieth), with subsequent grinding of both parts together.

There are various systems for improving the operation and increasing the life of exhaust valves. Among them the following deserve mention:

The use of special alloys in the seating area of the valves (stellite, nimonic, etc.);The rotating system of the valve that standardizes the temperature of the valve and its sea;Cooling of the valve and its seat.

II. Base on the above passage to answer the teacher's questions.III. Off-hand translation.IV. Free conversations about everyday life.

test 3I. Read and translate the following passage into Vietnamese Besides running and maintaining the main propulsion machinery of the ship, the Engineer Officer has

a great deal of auxiliary machinery to look after. Auxiliary machinery covers everything mechanical on board ship except the main engines and boilers. It includes almost all the pipes and fittings and the equipment needed to carry out a number of functions. These functions may be summarised as follows.

To supply the needs of the main engines and boilers, air compressors are used to supply compressed air for starting engines. Coolers are used for cooling either oil or water. Water for the boilers is also heated before being admitted into the boiler by feed water heaters. This increases the efficiency of the boiler.

To keep the ship dry and trimmed, this is done through the bilge and ballast pumping systems. The former removes water which has gathered in machinery, cargo and other spaces. The latter pumps water into and out of ballast tank. In general cargo ships, these systems are usually interconnected and served by the same pumps. In tankers and other bulk carriers, these systems are entirely separate, because these ships may need to ballast at 12,000 tonne /hour and therefore need larger pumps.

To supply domestic needs such as fresh water from distillation plant, sanitation from sewage plant and heating and ventilation from heaters and air-conditioners.

To apply the main power of the engines for propulsion and manoeuvring, the engine power is transmitted to the propeller by a line of steel shafting. This is made up of the thrust shaft, intermediate shaft and the propeller shaft. Steering gear is also necessary to operate the rudder for manoeuvring.

To supply the ship with electrical power and lighting, this is done by steam or diesel-powered generators.

II. Base on the above passage to answer the teachers’ questions.

III. Off-hand translation.



There are a number of reasons for wear in cylinder liners. Wear may be due to friction, corrosion and abrasion. Each of these may have a number of causes. Frictional wear depends on the materials used in the liner and in the piston rings. It takes place between the sliding surface of the cylinder liner and the piston rings. It may be caused by inefficient lubrication of the cylinder or by overloading the engine. In addition, engine operating conditions also affect frictional wear. For example, frictional wear may increase, if the air and fuel are contaminated. Corrosion occurs when heavy fuels with a high sulphur content are burned. It is caused by acids which are formed during combustion. Sulphuric acid corrosion may be caused if the cooling water temperature is too low. This allows moisture to condense in the cylinder cooling jacket and consequently sulphuric acid may form in the cylinder. Now let us look briefly at the causes of abrasion. Abrasion is caused by hard particles. These may be the product of combustion or mechanical wear. Hard particles may also be produced by corrosion.

We have shown, then, that cylinder liner wear is caused by friction between the lines and the piston rings, by corrosion – mainly from burning heavy fuels – and by abrasion from the products of wear, corrosion and combustion.





The standard cylinder lubricators, one per cylinder, are both speed dependent and load change dependent. They are controlled by the engine revolutions, and are mounted on the roller guide housings, and interconnected with shaft pieces. The lubricators have a “built-in” capability to adjust the oil quantity. They are of the “Sight Feed Lubricator” type and are provided with a sight glass for each lubricating point. The oil is led to the lubricator through a pipe system from an elevated tank (Yard’s supply).

Once adjusted, the lubricators will basically have a cylinder oil feed rate proportional to the engine revolutions. The Load Change Dependent system will automatically increase the oil feed rate in case of a sudden change in engine load, for instance during manoeuvring or rough sea conditions.

The lubricators can further be equipped with:+ No-flow and level alarm devices . . . . . . . . . . option: 4 75 152+ Electric heating of cylinder lubricator . . . . . . . option: 4 42 133.As an alternative to the speed dependent lubricator, a speed and mean effective pressure (MEP)

dependent lubricator can be fitted, option: 4 42 113 which is frequently used on plants with controllable pitch propeller.



IV. Free talk about everyday life.

test N0. 6


Before starting the engine, it is essential to check the oil storage tank of the main engine and compare the reading with the level reading at the time of the last shutdown. In this manner, one checks for possible contamination with cooling water, when the level increases, and, at the same time, for possible losses from the crankcase or from a pipe, if the level has dropped. When a new liner is installed in a cylinder of a two-cycle engine, it is necessary to increase the flow of lubricating oil in the cylinder, as well as reduce the load on that cylinder. This measure should be maintained for a certain amount of time in order to achieve a proper wear in fit between the piston rings and cylinder liners. When the oil pump hooked up to the main engine is not supplying enough pressure to the circuit, the standby pump automatically goes into operation, and then shuts down again once the pressure has been re-established. This situation arises rather frequently during engine operation.

Excessive oil losses in an engine installation are frequently caused by: + Losses in the oil coolers; + Malfunctioning of the valves during the cleaning of the filters of the lubrication system; + Burning of oil during engine combustion.In all cases, this loss is detected, as has been stated, by an abnormal and constant drop in the level on

the engine storage tank gauge.





During normal operation on heavy oil at sea, the oil is taken from the HO tanks, where it is stored. First, It is fed through a heater and next through a centrifuge for purification. It may then pass through a cooler, before being discharged to the steam-heated heavy oil service tanks. Two of these are usually fitted and they are used alternately. One tank is in use, while the other is being filled. These tanks are heated to a moderate temperature and self-closing drain valves are fitted to remove any water or sludge which may settle out. The oil is drawn from the service tank in use by pumps and discharged at low pressure to the fuel oil heater.

These pumps should be in duplicate. A relief valve on the pumps will return excess pressure to the system. A viscosity regulator is fitted at the heater discharge, through which the oil will pass. This automatically controls the temperature of the oil fuel leaving the heater to maintain its viscosity within close limits. A by-pass must be fitted to the viscosity regulator. The oil is then discharged through the fine strainer to the main engine fuel pump suctions. A pressure control valve is fitted in the system and excess oil is returned either to the heavy oil service tanks or a balancing tanks. A diesel fuel tank is included in the system with its discharge to the primary pump suctions through a change-over valve. By operating this valve, the engine may be operated on diesel oil. Change-over should be very gradual to allow temperatures in the system to stabilise. During this period, the excess oil will return either to the heavy oil service tanks or a balancing tank. After it has been pumped from the DO tanks, where it is stored, the diesel oil passes through a centrifuge for purification before entering the diesel oil tank.





The Chief Engineer is directly responsible to the Master for the satisfactory operation of all machinery and equipment. Apart from assuming all responsibility, his role is mainly that of consultant and adviser. It is not usual for the Chief Engineer to keep a watch. The Second Engineer is responsible for the practical upkeep of machinery and the manning of the engine room, he is in effect an executive officer. On some ships, the Second Engineer may keep a watch. The Third and Fourth Engineers are usually senior watch keepers or engineers in charge of a watch. Each may have particular areas of responsibility, such as generators or boilers. Fourth Engineers may be classed as Junior Engineers. They will make up as additional watch keepers, day workers on maintenance work or possibly act as Refrigeration Engineers. Electrical Engineers may be carried on large ships or where company practice dictates. Where no specialist Electrical Engineer is carried, the duty will fall on one of the engineers. Various engine room ratings will usually form part of the engine room complement. Donkeymen are usually senior ratings who attend the auxiliary boiler while the ship is in port. Otherwise they will direct the ratings in the maintenance and upkeep of the machinery space. A storekeepers may also be carried and on tankers. A pump man is employed to maintain and operate the cargo pumps. The engine room ratings , e.g. fireman , greasers, etc . are usually employed on watches to assist the engineer in charge.





BearingWhen the engine is shut down after long trips, it is appropriate to check, among other things, the play

of the big end bearings, also known as crankpin or bottom end bearing.To do this, the corresponding crankshaft is placed in its upper or lower position and the top clearance

is checked on all big end bearings using thickness gauges.

If everything is correct, these measurements should match those of the last measurement made.The upper part of the bedframe bearings usually has a circular groove to distribute oil, leading the oil

at the same time through ports in the crankshaft to the big end and small end bearings. Small and bearings are also known as crosshead pin bearings or top end bearings.

In three-metal bearings, if the radial or axial play, as indicated in the attached drawing, exceeds the limit recommended by the manufacturer of the engine, the bearings have to be replaced with new ones. These bearings are usually not repaired.

II. Base on the above passage to answer the teacher's questions.


IV. Free conversations about everyday life.

test 10


In addition to its complicated structure, the cylinder cover is subjected to the extreme heat and pressure of the combustion chamber and its interior is cooled by the cooling water. In 4-cycle engines, in particular, the temperature at the intake and exhaust ports is low for the former and high for the latter, thus tending to cause more cracks than in 2-cycle engines.

Therefore, to prevent a crack, uniform cooling must take place and a large quantities of cooling water of low temperature at start-up or in cold weather should not be delivered; nor should output be increased rapidly, or the flow of cooling water is halted immediately after the engine stops. The jacket is cleaned so that heat transmission is not impaired by scale and mud adhering to the jacket part.

If a crack occurs in the outside of the cylinder cover, patching is applied to it in the same way as for the cylinder. Although internal cracks are difficult to find, the exhaust becomes white due to the vaporized leaked water.





Boilers are used on board ship for producing steam. This steam may be used for driving the main engines, when steam turbines are fitted, or for driving auxiliary machinery such as the windlass. There are two basic types of boiler in use in ship: The Scotch boiler, which is a type of smoke-tube boiler, and the water-tube boiler.

The Scotch boiler consists of a cylindrical steel shell, which contains a furnace at the bottom. Two or more furnaces may be fitted, depending on the size of the boiler. The furnace is connected to a combustion chamber, situated in the middle part of the boiler. Leading from this combustion chamber to a smoke box are a large number of horizontal tubes. Some of these are used for supporting the middle section of the boiler and the combustion chamber. Connected to the smoke box are the uptakes for the waste gases. The furnace, the combustion chamber and the tubes are all surrounded by water.

The gases are heated in the furnace by the heat from flames and from the sides of the furnaces. The hot gases then enter the combustion chamber. Like the furnace, this is also surrounded by water and so again provides for the generation of steam. From the combustion chamber, the gases pass through the smoke tubes, where the surrounding water is exposed to a greater area of heated surface. After leaving

the smoke tubes, the gases enter the smoke box and after that the uptakes. The steam generated collects in the top of the boiler.

The Scotch boiler is usually of both riveted and welded construction. It is strong and is capable of operating with poor quality feed water. But there are more efficient types of boiler which can generate more power, therefore Scotch boilers are now mainly used for auxiliary purposes on board ship...





... Water-tube boilers have replaced Scotch boilers for generating steam for main engines. They have a steam drum at the top, which is partly filled with water, and water drums at a lower level. These drums are connected by banks of tubes, which also contain water. The furnace is located at the bottom and the whole system is contained in a fire-proof casing. Downcomer tubes are placed outside the gas system to act as feeders to the water drums.

Gases are heated in the furnace and pass upwards through the banks of tubes, transferring their heat to the water in the tubes. Because the steam drum provides a reservoir of relatively cool water, convection currents are set up causing the water to circulate round the system. The banks of tubes offer a large surface area to the radiant heat of the furnace gases. This makes them very efficient. Superheaters are added to the system to increase its efficiency. These are located between the rows of tubes.

Various valves and gauges are fitted to the boilers. Those attached directly to the pressure parts of the boiler are known as boiler mountings. For a water-tube boiler, these include the following: safety valves, which are needed to release any excess steam from the boiler; a main stop valve in order to control the passage of steam to the engines; feed check valves to control the final entry of water into the boiler; water level indicators to show the level of water in the boiler and thermometers for showing the temperature inside the boiler. In order to be able to drain water from the system, drain valves are fitted. Salinometer valves are also fitted to allow samples of water to be drawn off for testing. Chemical dosing valves are also necessary so that chemicals can be added directly into the boiler.





GovernorsThe governor or speed regulator is the part of the engine that maintains the engine speed constant

regardless of the engine load.The degree of sensitivity of a governor is its reaction to a variation in speed. When a governor loses

sensitivity, it has to be repaired, because engine speed variations would otherwise be too sharp. The governor is mechanically activated through direct transmission off the engine. This transmission

is from the distributor through the vertical shaft.The governor controls the injection pumps through a connection system generally consisting of

mechanical linkage.

If the connecting system breaks, the engine tends to race. To prevent this, the engine has overspeed safety systems. Some of these systems stop the engine by cutting off fuel, and others limit pump capacity, preventing them from increasing the fuel supply.




test NO. 14


In a marine Diesel the fuel pump is filled with fuel and the latter is forced into the delivery line by means of delivery valves.

Depending on the method employed for controlling the amount of fuel supplied to the delivery manifold, pumps are classified as pumps adjustable at the end of the delivery stroke, at the beginning of the delivery stroke and with combination adjustment, i.e. both at the beginning and end of the delivery stroke.

In the first type of pumps, the delivery stroke can be adjusted by changing the end of fuel delivery, in the second type, the beginning of fuel delivery can be changed, and in the third type both, the beginning and the end of delivery, can be adjusted.

In pumps with valve-controlled end of fuel delivery; the adjustments are effected with the aid of a special cut-off valve which opens at the end of delivery stroke.

In port control pumps, the valves are replaced by suction ports which also serve for bypassing the fuel from the delivery chamber into the suction chamber. The portion of fuel supplied to the cylinders is metered here by the plunger which has a special helical cut-out or helix for the purpose.




test 15


Boiler Repairs

When a boiler tube fails, it should be taken out of service. Eliminate the pressure by opening the air cock so that there will be circulation that will cool it as the pressure drops, thereby preventing damage to the tube from possible superheating. Accordingly, the boiler should not be purged through the bottom valves unless the breakdown is serious and endangers human lives, in which case it will be discharged directly to the sea through the bottom blow sea valve.

In either of these two cases, it is necessary to keep the forced draft ventilator in operation to cool the boiler and, at the same time, to scavenge any vapors that might be produced.

Excessive draft air for furnace cooling should be avoided to prevent damage to refractory material. Only if the boiler failure causes a pressure rise in the furnace should excess draft air be used for cooling.

When any welding is done on the boilers, all the welds should be checked by means of X-rays.X-rays, because they consist of extremely short waves, pass readily through material and produce

photographic impressions, recording all the defects that may be found in the weld air blowholes, incrusted slag, etc.

Whenever a boiler is fired and shut down, it is advisable to check slippage of the boiler supports in their guides. If any misalignments are noted, they must be corrected because otherwise, stresses will be produced in the structure of the boilers.




test 16


When the play between the injector needle and its nozzle is excessive, both parts must be changed; it is not advisable in any case to replace only one of them, because they are adjusted to one another by the manufacturer.

If only one of the parts is replaced, it could lead to a seizing of the needle in the nozzle or, at least, to breakdowns in injector setting.

The injectors are cooled by means of water or fuel, though at present cooling means of the fuel itself is more widely used.

The abandonment of water cooling is due to the risk of corrosion both in the injector itself and in the adjacent areas of the inside of the cylinder, when there is loss of water tightness in the water area. At the same time, cooling with the fuel itself has the advantage of construction simplicity.

The needle of the injector nozzle must fall gently into the nozzle-holder case of its own weight, the nozzle itself being slightly tilted. Inserting it with a certain pressure would mean that the fit is too tight, which could cause the needle to seize.




test 17


Cylinder lubrication has the primary function of forming a film between liner and rings to prevent the escape of combustion gases and, at the same time, to reduce the friction between liner and rings, preventing them from getting hot and reducing the speed of wear.

Cylinders are generally lubricated through a series of orifices at different heights and at various points in the liner. Oil is supplied by one or more pumps driven by the main engine, which pushes the oil through pipes of small diameter which discharge to the ports in the cylinder liner.

Knocking in one or more cylinders can be caused by injection failure, overload on the engine and high fuel pressure. However, a governor failure could cause a variation in the amount of fuel injected and therefore in engine revolutions, but has no connection with the knocking of the engine.




test 18


Seizing of the piston rings in an engine generally produces dark surfaces on the upper portion of the liner due to the fact that, since the rings cannot move freely in their grooves because of deposits of codified oil, combustion gases pass between the piston rings and the cylinder wall. The cause of these deposits is generally improper combustion, either because of poor injector functioning, or because of an inadequate air-fuel ratio.

The inside of the liner should be measured, without removing it from the cylinder, using a micrometer gauge that is at the same temperature as the liner. If possible, these measurements should be made at three different levels on the liner, measuring the diameter at that level in port-starboard and bow-stern directions.

Lack of cooling inside the pistons can cause cracks in the piston crown and other substantial damage. Under suitable conditions, carbon deposits can form inside the piston that will prevent the transmission of heat from the combustion chamber to the piston.




test 19


In two-strokes cycle engines, to make a complete separation between the space inside the cylinder where combustion takes place and the engine crankcase, there is a piston rod stuffing box, which among other functions, prevents contamination of the scavenging air by the oils and gases from the engine crankcase. In two-cycle engines, when the piston rings are stuck or broken, combustion gases can infiltrate between the liner and the piston and pass through the ports in the liner to the scavenging air manifold,

causing the blowing of the oil sediments inside the scavenger manifold. This phenomenon is known as “blow-by” and occurs if the leaks involved are major. The Classification Societies require a full set of rings for a piston as a mandatory spare to be carried aboard ships sailing the high seas. Piston rings can break due to knocking against the surfaces of the liner and the piston, or because of irregularities in the liner wall. Broken rings, even if not visibly broken, can be identified by the fact that they are darker in color and lack elasticity when pushed toward the inside of their grooves. The clearance between the end of piston rings must be sufficient to permit heat expansion of the rings, since they work at a higher temperature than the liner. The play is checked by placing the ring at the bottom of the cylinder liner which generally does not suffer any wear in this area.




test 20


To separate dirt and water from oil, it is a common practice to use settling tanks and filters, centrifugal oil filters or oil centrifuges. In a centrifuge, the oil is delivered onto rapidly rotating cones. Under the effect of the centrifugal force, any dirt and water contained in the oil are separated due to higher specific weight, being thrown into the periphery.

The dirt, having a higher specific weight than the oil, settles on the vertical walls of the rotor and gradually fills the dirt chamber. The water accumulates in the rotor whereas the cleaned oil is concentrated near the axis of rotation.

The oil discharged from the engine is cooled by surface tubular oil coolers in which the oil flows around brass tubes while the cooling sea water flows inside the tubes. As a rule, the ends of the tubes are expanded in two tube plates. One of these is free to move this providing for elongation of the tubes due to heating.

In some types of oil coolers, protection is made for tube elongation by introducing an expansion piece or joint in the cooler shell.

The water chambers of the cooler and heads are provided with zinc protectors to prevent corrosion of the parts washed by sea water. The cooler reduces the oil temperature by 10 – 15OC and the cooling water gets heated by 4 – 6OC.




test 21


OperationIf, during normal sailing of a turbine-driven ship, a loss of power, a drop-off in speed, or a change in

the tone of the engine noise in noted, this can be due among other things to a fluctuation in pressure in the boilers, or to steam strainer . A sudden change in the ship's heading also causes a loss of speed and a change in the engine noise.

Since some crews have the idea that ocean currents can produce the above-mentioned effects, it is appropriate to stress that this is not true, since the current does not affect the relative movement of the ship.

When berthing operations have been completed, and during the turbine cooldown operation, the steam supply to the gland seal has to be kept open. Otherwise, cold air with enter form the outside through the plugs, since the condenser is still in a vacuum, and this can cause deformations of the turbine.




test 22


Oily Water SeparatorBilge water is discharged through the oily water separator by means of a pump which sucks from the

bilge manifold and discharges to the separator. This pump is generally of the reciprocating type, since the

use of a centrifugal type pump for this purpose would produce an emulsion of water and oil and the

separator would have difficulty operating properly.

The separator's steam coil is used to heat up the mixture, causing a reduction in its viscosity. In this

way, it becomes easier to discharge the oil when the temperature is low.

In any event, contrary to what might otherwise appear, it has no positive effect on separator's

performance.




test 23


Turning Gear

The turning gear is a device that makes it possible to turn the engine when it is shut down so as to put it into the desired position for any type of repair or checking of its parts.

Before hooking up the turning mechanism, it is necessary to make sure the starting air is shut off, that the indicator cocks (drains) are open, and that the "engine engaged" sign has been posted.

Otherwise, the engine could be started by a false maneuver with the turning gear engaged, causing damage to the engine and injury to personnel.

It is appropriate to turn the engines slowly during the half-hour preceding startup of the engine, putting the on pump into action and circulating the cooling water through the water heater, in order to make sure the oil lubricates all points of the engine and that the engine temperature is closer to operating temperature.




test 24


VentilationTo prevent noises and vibration in a ventilator installation, the ventilator is positioned so that a liner

can be inserted between the base of the seat and its support to dampen vibrations. This liner can be made of wood, rubber or any other similar material. This cushioning is especially important in the case of ventilators that are intended to ventilate living quarters.

Although the ideal ventilation for a purifying chamber is the type consisting of mixed ventilation with forced intake and exhaust, usually, for reasons of simplicity and economy, only an extractor is installed, thereby eliminating the mixing of air and fuel vapors from the fuel and oil in the purifiers, which is very dangerous. In the area of the engine room containing the generator sets, ventilators are installed and directed toward the generator sets, with a double mission: to cool the generator and, at the same time, by renewing the air, to eliminate any condensation that could form inside the set because of moisture in the air.




test 25


Air CompressorsDouble-acting and high pressure air compressors are equipped with pistons of different diameters,

with the low pressure piston being the larger of the two.The reason while the high pressure compressors are not built in a single phase is that the temperature

that the air would attain if compressed in a single stage would be such that it could cause the compressor head materials to overheat. For this reason, compressors of several stages are used with air cooling between the various stages comprising the compressor.

To regulate the compressed air supplied by the compressors, the intake air volume of flow is adjusted and, to that end, compressors are equipped with a flap valve in the intake manifold. Compressor production is therefore regulated by operating this valve.

In an air compressor, oil from the lubrication of the moving part that mixes with the air is eliminated by mean of bleeders that are installed on each stage of the compressors and in the air pressure tank.




test 26


Distilled Water Generator

The internal part of the distilled water generator is cleaned by the circulation of a chemical, because the use of mechanical means would damage the protective coating on the inside of the evaporator.

The most significant indication that a water generator is dirty is a substantial decrease in its performance, since the salts contained in the sea water tend to adhere to the pipes, acting as heat insulation and decreasing the production of distilled water.

In the event the salinity indicator of the distilled water generator indicates a salinity level in the water produced in excess of 50 parts per million (p.p.m), the drain valve to the bilges must be opened immediately in order not to contaminate the distilled water storage tank.




test NO. 27


Turbine Heating

When starting up a turbine, it should be borne in mind that when a condenser is put into operation, it is necessary, among other things, to open all air bleeds of the water jackets to make sure there are no air pockets that would affect the performance of the condenser. The pockets would prevent the upper part of the heads from filling up, and since there would be no water circulating in the upper tubes, this would cause a reduction in the effective cooling surface. When preparations are being made to start up the turbine, once starting temperature has been reached, and after the turning gear has been disconnected, it can not be kept stopped more than about three minutes, as the rotor would be deformed. In order not to keep it stopped, it is necessary to implement "autospinning" or balancing by alternately opening the ahead and astern valves.




test 28


1. When working clothes are selected for use in machinery spaces, consideration should be given to the hazards to which the wearer may be exposed. Personnel should ensure that clothes fit well and have no loose flaps or strings. External pockets, if any, should be as few and as small as possible. A shirt with short sleeves should be worn in preference to one with rolled up sleeves.

2. Loose, torn or ragged garments are a hazard when working near moving machinery. Special attention is drawn to the hazards of neck ties, sweat rags slung round the neck, and the wearing of finger rings in the machinery spaces.

3. Special caution is necessary when working near machinery in motion, particularly in close proximity to a revolving shaft.

4. Suitable goggles should always be worn when working near machinery in motion, grinding, drilling, working a lathe, scaling, hammering, using a cold chisel or doing any work of a similar nature.

5. Every effort should be made to ensure that any oil falling on floor plates be removed as quickly as possible. Nevertheless, floor plates tend to become slippery and this, combined with the movement of the ship at sea, makes footholds insecure. When floor plates are slippery with oil, there is a risk that heavy machinery which is being lifted may be inadvertently dropped, causing severe foot injuries. The risk of injury is reduced by the use of industrial footwear (not having steel studs and preferably with soles having oil-resistant anti-slip characteristics).




test 29


The pumps which are used on board ship can be divided into two main groups: displacement pumps and centrifugal pumps. In displacement pumps, the volume of the pump chamber is increased by raising the piston. This causes a vacuum into which the liquid is drawn from the suction pipe. The piston is then lowered, decreasing the volume of the pump chamber and forcing the liquid out into the delivery pipe. Centrifugal pumps consist of and impeller, which rotates at high speed, inside a casing. The liquid, which enters through a suction pipe at the centre, is thrown by centrifugal force against the surrounding casing. It is then discharged through the delivery outlet. A simple kind of reciprocating displacement pump is the single-acting ram pump, which consists of a ram moving up and down inside a chamber fitted with a non-return suction valve and a non-return delivery valve. When the piston moves up, a vacuum is formed in the chamber into which liquid is drawn through the suction valve. Then the piston moves down, creating a force on the liquid which closes the suction valve and forces the liquid out through the delivery valve. Another type of reciprocating pump is the double-acting piston pump, which works on the same principle as the single-acting pump. The chamber is fitted with suction and return valves at the top and bottom, consequently the liquid can be drawn in and discharged on each stroke.




test 30


Maintenance schedule of marine diesel engine

Engine builders supply detailed instructions on the operation and maintenance of their machinery so that regular maintenance work can be carried out and breakdowns can be kept to a minimum. These instruction manuals are usually kept by the Chief Engineer, but they are made available to all members of the engine-room staff. The intervals at which an engine and its parts must be inspected will vary from make to make and will depend on the use the engine has been put to, and therefore the brief outline which follows is meant only as a general guide.

At frequent intervals, fuel pumps should be examined and adjusted if necessary. When the engine is running, this will be shown by comparing engine indicator cards and by exhaust temperatures. Pistons should also be examined frequently for cracks.

At intervals of six weeks, the fuel valves should be taken out and carefully inspected. Atomizers and filters can be washed with clean paraffin and then dried in a warm place. Cleaning rags must not be used because they leave behind small pieces of fluff, which may block up holes. Valve seats should also be tested and if they are pitted or scratched, the surface should be reground.

If possible, the upper piston rings should be examined at intervals of one month during the first six months' service. After that, inspection periods can be extended so long as their condition continues to be satisfactory.




TEST 31.

THE WATCHKEEPING SYSTEM.

The system of watches adopted on board ship is usually a four hour period of working with eight hours for the members of each watch. The three watches in any 12 hour period are usually 12-4, 4-8, and 8-12.The word ‘watch’ is taken as meaning the time period and also the personnel at work during that period. The watchkeeping arrangements and the make up of the watch will be decided by the Chief Engineeer. Factors to be taken into account in this matter will include the type of ship, the type of machinery and degree of automation, the qualifications and experience of he members of the watch, any special conditions such as weather ,ship location , international and local regulations, etc. The engineer officer in charge of the watch is the Chief Engineer’s representative and is responsible for the safe and efficient operation and upkeep of all machinery affecting the safety of the ship.

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Cau hoi thi SQVH