Mech Interview Questions

7/28/2019 Mech Interview Questions

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What are the different types of fits? Explain?On the basis of Indian standards fits can mainly be categorized into three groups:> Clearance Fit: These types of fits are characterized by the occurrence of a clearance between the twomating parts. The difference between the minimum size of the hole and the maximum size of the shaft is callethe minimum clearance, the difference between the maximum size of the hole and the minimum size of theshaft is known as maximum clearance.> Interference Fit: In these types of fits the size of the mating parts are predefined so that interference betweethem always occurs. The tolerance zone of the hole is completely below the tolerance zone of the shaft.> Transition Fit: As the name suggests these type of fit has its mating parts sized limited to allow either

clearance or interference. The tolerance zone of the hole and the shaft overlaps in case of such fits.

For a shaft designated as 40 H8/f7, calculate the tolerances.Given: Shaft designation = 40 H8/f7The shaft designation 40 H8/f 7 means that the basic size is 40 mm and the tolerance grade forthe hole is 8 ( i. e. I T 8) and for the shaft is 7 ( i. e. I T 7).Since 40 mm lies in the diameter steps of 30 to 50 mm, therefore the geometric mean diameter,D = Square root of (30 x 50) = 38.73 mmWe know that standard tolerance unit,i = 0.45 x Cube root of (D) + 0.001 Di = 0.45 3.38 + 0.03873 = 1.559 73 or 1.56 micronsi = 1.56 0.001 = 0.001 56 mm ...(1 micron = 0.001 mm)

The standard tolerance for the hole of grade 8 (IT8)= 25 i = 25 0.001 56 = 0.039 mmThe standard tolerance for the shaft of grade 7 (IT7)= 16 i = 16 0.001 56 = 0.025 mm

What are the factors that can affect the Factor of safety selection? The factor of safety is used in designing a machine component. Prior to selecting the correct factor of safetycertain points must be taken into consideration such as:> The properties of the material used for the machine and the changes in its intrinsic properties over the timeperiod of service.> The accuracy and authenticity of test results to the actual machine parts.> The applied load reliability.

> The limit of stresses (localized).> The loss of property and life in case of failures.> The limit of initial stresses at the time period of manufacture.> The extent to which the assumptions can be simplified.The factor of safety also depends on numerous other considerations such as the material, the method ofmanufacturing, the various types of stress, the part shapes etc.

What is heat treatment and why is it done?Heat treatment can be defined as a combination of processes or operations in which the heating and cooling a metal or alloy is done in order to obtain desirable characteristics without changing the compositions. Some othe motives or purpose of heat treatment are as follows:> In order to improve the hardness of metals.

> For the softening of the metal.> In order to improve the machinability of the metal.> To change the grain size.> To provide better resistance to heat, corrosion, wear etc.

Heat treatment is generally performed in the following ways:> Normalizing> Annealing> Spheroidising> Hardening> Tempering> Surface or case hardening


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What are the rules that must be kept in mind while designing castings?Some of the points that must be kept in mind during the process of cast designing are as follows:> To avoid the concentration of stresses sharp corners and frequent use of fillets should be avoided.> Section thicknesses should be uniform as much as possible. For variations it must be done gradually.> Abrupt changes in the thickness should be avoided at all costs.> Simplicity is the key, the casting should be designed as simple as possible.> It is difficult to create true large spaces and henceforth large flat surfaces must be avoided.> Webs and ribs used for stiffening in castings should as minimal as possible.

> Curved shapes can be used in order to improve the stress handling of the cast.

What are the points that should be kept in mind during forging design?Some of the points that should be followed while forging design are:> A radial flow of grains or fibers must be achieved in the forged components.> The forged items such as drop and press forgings should have a parting line that should divide the forginginto two equal halves.> The ribs in a forging should not be high or thin.> In order to avoid increased die wear the pockets and recesses in forgings should be minimum.> In forgings the parting line of it should lie as far as possible in a single plane.> For ease of forging and easy removal of forgings the surfaces of the metal should contain sufficient drafts.

Describe briefly the different cold drawing processes.Some of the important cold drawing processes are as follows:> Bar and Rod Drawing: In the case of bar drawing the hot drawn bars are at first pickled, washed and coatedto prevent oxidation. Once this is done a draw bench is used for the process of cold drawing. In order to makean end possible to enter a drawing die the diameter of the rod is reduced by the swaging operation. This end fastened by chains to the draw bench and the end is gripped by the jaws of the carriage. In this method a highsurface finish and accuracy dimensionally is obtained. The products of this process can be used directlywithout any further machining.> Wire Drawing: Similar to the above process the bars are first pickled, washed and coated to prevent anyoxidation. After this the rods are passed through several dies of decreasing diameter to provide a desiredreduction in the size ( diameter ). The dies used for the reduction process is generally made up of carbidematerials.

>Tube Drawing: This type of drawing is very similar to the bar drawing process and in majority of cases it isaccomplished by the use of a draw bench.

What are the different theories of failure under static load, explain briefly?The main theories of failure of a member subjected to bi-axial stress are as follows:> Maximum principal stress theory ( Rankines theory): This theory states that failure occurs at a point inmember where the maximum principal or normal stress in a bi-axial system reaches the maximum strength insimple tension test.> Maximum shear stress theory ( Guests or Trescas theory): This th eory states that failure occurs when thebiaxial stress reaches a value equal to the shear stress at yield point in a simple tension test.> Maximum principal strain theory ( Saint Venant theory): This theory states that failure occurs when bi-axialstress reaches the limiting value of strain.

> Maximum strain energy theory ( Haighs theory): This theory states that failure occurs when strain energy peunit volume of the stress system reaches the limiting strain energy point.> Maximum distortion energy theory ( Hencky and Von Mises theory): This theory states that failure occurswhen strain energy per unit volume reaches the limiting distortion energy.

What are the assumptions made in simple theory of bending?The assumptions made in the theory of simple bending are:> The material of the beam is homogeneous this implies that it is uniform in density, strength and haveisotropic properties meaning possessing same elastic property in all directions.> Even after bending the cross section of the beam remains constant.> During the initial stages the beam is straight and unstressed.> All the stresses in the beam are within the elastic limit of its material.


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> The layers of the beam are free to contract and expand longitudinally and laterally> On any cross section the perpendicular resultant force of the beam is zero.> Compared to the cross-sectional dimension of the beam the radius of curvature is very large.

Why stress is considered important in a shaft?The following types of stresses are prevalent in shafts:> At the outermost surface of the shaft the max shear stress occurs on the cross-section of the shaft.> At the surface of the shaft on the longitudinal planes through the axis of the shaft the maximum longitudinalshear stress occurs.

> At 45 degrees to the maximum shearing stress planes at the surface of the shafts the major principal stressoccurs. It equals the max shear stress on the cross section of the shaft.> For certain materials where the tensile and compressive strengths are lower in measure as compared to theshear strength, then the shaft designing should be carried out for the lowest strengths.> All these stresses are of significance as they play a role in governing the failure of the shaft. All thesesstresses get generated simultaneously and hence should be considered for designing purposes

What do you understand by the Hooke`s Coupling what are its purposes?The Hooke`s coupling is used to connect two shafts whose axes intersect at a small angle. The two shafts areinclined at an angle and is constant. During motion it varies as the movement is transferred from one shaft toanother. One of the major areas of application of this coupling is in gear boxes where the coupling is used todrive the rear wheels of trucks and other vehicles. In such usage scenarios two couplings are used each at th

two ends of the coupling shaft. they are also used to transfer power for multiple drilling machines. The Hookecoupling is also known as the Universal coupling. The torque transmitted by the shafts is given by:T= (pie/16) x t x (d) cubeWhere T = torque, t = shear stress for the shaft material and d the diameter of the shaft.

What kind of materials should be used for shafts manufacturing?Some of the qualities that should be present in materials for shafts are as follows:> The material should have a high index of strength.> Also it should have a high level of machinability.> The material should possess a low notch sensitivity factor.> The material must also have wear resistant properties.> Good heat treatment properties should also be present

The common material used to creates shafts of high strengths an alloy of steel like nickel is used. The shaftsare manufactured by hot rolling processes and then the shaft is finished using drawing or grinding processes.

During the design of a friction clutch what are the considerations that should be made?In order to design a friction clutch the following points must be kept in mind:> The material for the contact surfaces must be carefully selected.> For high speed devices to minimize the inertia load of the clutch, low weight moving parts must be selected> The contact of the friction surfaces must be maintained at all the times without the application of any externforces.> Provisions for the facilitation of repairs must be there.> In order to increase safety the projecting parts of a clutch must be covered.> A provision to take up the wearing of the contact surfaces must be present.

> Heat dissipaters to take away the heat from the point of contacting surfaces must be there.

What are the different types of brakes and explain them briefly?Brakes can be classified on the basis of their medium used to brake, they are as follows:> Hydraulic Brakes: These brakes as their name suggest use a fluid medium to push or repel the brake padsfor braking.> Electric Brakes: These brakes use electrical energy to deplete or create a braking force.Both the above types of breaks are used primarily for applications where a large amount of energy is to betransformed.> Mechanical Brakes: They can be further classified on the basis of the direction of their acting force: RadialBrakes: As their names suggests the force that acts on the brakes is of radial direction. They can further be


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classified into internal and external blades. Axial Brakes: In these types of brakes the braking force is acting inan axial direction as compared to radial brakes.

On what basis can sliding contact bearings be classified? Explain?Sliding contact bearings can be classified on the basis of the thickness of the lubricating agent layer betweenthe bearing and the journal. They can be classified as follows:> Thick film bearings: These type of bearings have their working surface separated by a layer of the lubricantThey are also known as hydrodynamic lubricated bearings.> Thin film bearings: In this type of bearings the surfaces are partially in direct contact with each other even

after the presence of a lubricant. The other name for such type of bearings is boundary lubricated bearings.> Zero Film Bearings: These type of bearings as their name suggests have no lubricant present between thecontact layers.> Externally or hydrostatically pressurized lubricated bearings: These bearings are able to without any relativemotion support steady loads.

What are the basis on which the best material for Sliding Contact Bearings manufacturing?Some of the important properties to lookout for in the material for sliding contact bearings are as follows:> Compressive Strength: In order to prevent the permanent deformation and intrusion of the bearing thematerial selected should be possess a high compressive strength to bear the max bearing pressure.> Fatigue Strength: the material selected for the bearing should be able to withstand loads without any surfacfatigue cracks getting created. This is only possible if the material has a high level of fatigue strength.

> Comfortability: The material should be able to adjust or accommodate bearing inaccuracies and deflectionswithout much wear and heating.> Embeddability: The material should allow the embedding of small particles without effecting the material ofthe journal.> Bondability: The bearings may be created by bringing together ( bonding ) multiple layers of the material.Due to the above reason the bondability of the material should be sufficiently high.> Thermal conductivity and corrosion resistance: Thermal conductivity is an essential property for bearingmaterials as it can help in quickly dissipating the generated heat. Also the material should have a level ofcorrosion resistance against the lubricant.

Briefly explain the advantages of Cycloidal and Involute gears?The advantages of the Cycloidal gears are as follows:

> Having a wider flank as compared to Involute gears they are considered to have more strength and hencecan withstand further load and stress.> The contact in case of cycloidal gears is between the concave surface and the convex flank. This results inless wear and tear.> No interference occurs in these types of gears.The advantages of Involute gears are as follows:> The primary advantage of involute gears is that it allows the changing of the centre distance of a pair withouchanging the velocity ratio.> The pressure angle remains constant from start to end teeth, this results in less wear and smooth running othe gears.> The involute gears are easier to manufacture as they can be generated in a single curve ( the face and flank).

How can the reaction of support of a frame be evaluated?Generally roller or hinged support are used to support the frames. The conditions of equilibrium are used todetermine the reaction support of a frame. The condition of equilibrium takes place when the sum of thehorizontal and vertical forces sum equal to zero. The system must form a state of equilibrium even afterconsidering the external loads and the reactions at the supports. For equilibrium to be prevalent in the systemthe following conditions are required to be in occurrence:> Summation of V = 0. This implies that the summation of all the forces in the vertical direction results to zero> Summation of H = 0 . This implies that the total of all the forces acting in horizontal direction is also zero.> Summation of M = 0. The sum of all the moment of forces around a point must be zero.


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Explain in an orderly manner how the force in the member of a truss be detected using the method ofjoint.The steps required to calculate the force are as follows:> The reaction at the support has to be first calculated.> Once the reaction is calculated the direction of force of the member is made to make it tensile. On getting thresult to be negative the direction assumed is wrong and this implies the force being compressive in nature.> A joint needs to be selected whose 2 members are not known. The lami`s theorem is used on the joint onwhich less than three forces are acting.> After the above process is complete the free body diagrams of the joint needs to be made. Since the system

is in equilibrium the condition of Summation of V and H must result in zero.> After the above step the resolution of forces method needs to be used on the joint on which more than 4forces are acting.

In order to derive the torsional formulas what are the assumptions taken?The torsion equation is derived on the basis of following assumptions:> The shaft material is uniform, throughout the shaft.> Even after loading the shaft circular remains circular.> After the application of torques the plain section of a shaft remains plain.> Any twist that occurs in the shaft remains uniform and constant.> After the application of torque the distance between any two cross-sectional references remains constant.> The elastic limit value of a shaft is never exceeded even after the shear stress induced because of torque

application.

What are Bevel Gears and what are its types?Bevel gears are the type of gears in which the two shafts happen to intersect. The gear faces which are toothbearing are conical in shape. They are generally mounted on shafts which are 90 degrees apart but they canbe made to work at other angles as well. The bevel gears are classified into the following types on the basis opitch surfaces and shaft angles:> Mitre Gears: These types of gears are similar to each other ie. they have the same pitch angles and containthe same number of teeth. The shaft axes intersect at 90 degrees angle.> Angular bevel gears: When two bevel gears connect at any angle apart from 90 degrees.> Crown bevel gears: When the two shaft axes intersect at an angle greater than 90 and one of the bevelgears have a pitch angle of 90 degrees they are known as crown bevel gears.

> Internal bevel gears: In these type of gears the teeth on the gears is cut on the inside area of the pitch cone

What are the different values that need to be determined in order to design a cylinder for an ICE?The following values are needed to be determined:> Thickness of the cylinder wall: The cylinder walls in an engine are made witness to gas pressure and theside thrust of a piston. This results in two types of stresses: longitudinal and circumferential stress. Both thetypes of stresses are perpendicular to each other and hence it is aimed to reduce the resulting stress as mucas possible.> Length and bore of the cylinder: The length of the cylinder and the length of the stroke is calculated on thebasis of the formula: length of cylinder L = 1.15 times the length of the stroke (l). L = 1.15(l)> Cylinder flange and studs: The cylinders are always cast integral as a part of the upper crankcase or in somcases attached to it by means of nuts and bolts. The flange is integral to a cylinder and henceforth its thickne

should be greater than that of the cylinder wall. The thickness of flange should generally be between 1.2t-1.4twhere t is the cylinder thickness.The stud diameter is calculated by equating gas load (due to max pressure ) to the grand total of all theresisting forces of the studs.

What are considerations taken into account while creating a piston head?The piston head is designed on the basis of the following considerations:> The crown should have enough strength to absorb the explosion pressure inside the engine cylinder.> The head must always dissipate the heat of the explosion as quickly as possible to the engine walls. Thethickness of the head is calculated on the basis of another formula which takes into consideration the heatflowing through the head, the conductivity factor of the material. The temperature at the center and edges ofthe head.


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> The thickness of the piston head is calculated on the basis of the Grashoff`s formula which takes intoconsideration the maximum gas pressure of an explosion , the permissible bending and the outside diameter the piston.

Why should a chain drive be used over a belt or rope driven drive? State pro`s and con`s?The advantages of using a chain drives are:> In a chain drive no slip occurrence takes place.> The chains take less space as compared to rope or belts as they are made of metal and offer much strength> The chain drives can be used at both short and long ranges and they offer a high level of transmission

efficiency.> Chain drives can transmit more load and power as compared to belts.> A very high speed ratio can be maintained in one step of chain drives.Some of the cons of using a chain drive are:> The cost of producing chain drives is higher as compared to that of belts.> The chain drives must be serviced and maintained at regular intervals and henceforth their cost of ownershis high comparatively.

What are the different types of springs and explain them briefly?Springs can be broadly classified into the following types:> Helical Springs: These springs as their name suggests are in coil form and are in the shape of helix. Theprimary purpose of such springs are to handle compressive and tensile loads. They can be further classified

into two types: compression helical spring and tension helical spring each having their own unique areas ofapplication./> Conical and volute springs: Both these spring types have specialized areas of usage where springs withadaptable rate according to the load is required. In case of conical springs they are wound so as to have auniform pitch while on the other hand volute springs are wound in a slight manner of a parabloid.> Torsion Springs: The characteristics of such springs is that they tend to wind up by the load. They can beeither helical or spiral in shape. These types of springs are used in circuit breaker mechanisms.> Leaf springs: These types of springs are comprised of metal plates of different lengths held together with thhelp of bolts and clamps. Commonly seen being used as suspensions for vehicles.> Disc Springs: As the name suggests such types of springs are comprised of conical discs held together by abolt or tube.> Special Purpose Springs: These springs are all together made of different materials such as air and water.

What is the importance of the Thermodynamics in the field of Mechanical Engineering?All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is veryimportant for the mechanical engineers.

How many Laws of Thermodynamics are there?There are three laws of the thermodynamics.First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in anisolated system, the total energy remains the same.Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamicequilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breakinthe isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a

mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than orequal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamicequilibrium, entropy has increased, or at least has not decreased.Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.

State Laws of conservation of energy?According to the laws of conservation of energy, energy can neither be created nor be destroyed. It can onlybe transformed from one form to another.

Is the boiler a closed system?Yes definitely the boiler is a closed system.


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What is Carnot engine?It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which followsthe Carnot cycle and provides 100% efficiency.

Which formula forms a link between the Thermodynamics and Electro chemistry? Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics andelectromagnetism.

Hs/R = [ lnp / (1/T)]x

where: x mole fraction of CO2 in the liquid phasep CO2 partial pressure (kPa)T temperature (K)R universal gas constant mole ratio in the liquid phase (mole CO2 per mole of amine)

Which is the hardest compound known?Diamond.

What is Hess Law?According to the Hess law the energy transfer is simply independent of the path being followed. If the reactanand the product of the whole process are the same then same amount of energy will be dissipated or

absorbed.

Which has more efficiency: Diesel engine or Petrol engines?Off course Diesel engine has the better efficiency out of two.

What is the difference between Critical Speed and Whirling Speed?In Solid mechanics, in the field of rotor dynamics, the critical speed is the theoretical angular velocity whichexcites the natural frequency of a rotating object, such as a shaft, propeller or gear. As the speed of rotationapproaches the objects natural frequency, the object begins to resonate which dramatically increases systemvibration. The resulting resonance occurs regardless of orientation. Whirling Speed is due to the unbalancedforces acting on a rotating shaft.

How a Diesel Engine Works as Generator?Diesel engine is a prime mover, for a generator, pump,and for vehicles etc. generator is connected to engineby shaft. mostly in thermal power plat ,there is an engine is used to drive generator to generate power.

Explain Second Law of Thermodynamics?The entropy of the universe increases over time and moves towards a maximum value.

Compare Brayton Cycle and Otto Cycle?The heat addition and rejection processes in Otto cycle are of constant volume, whereas in Brayton cycle, theare of constant pressure. Otto cycle is the ideal cycle for spark ignition engines. Brayton cycle is the ideal cycfor gas power turbines.

What is the purpose of Scrapper Ring?scrap the excess lube oil from the cylinder walls. there by preventing oil from entering combustion zone.

What is DTSI Technology?DTSI stands for Digital Twin Spark Plug Ignition. The vehicles with DTSI Technology use 2 spark plugs whichare controlled by digital circuit. It results in efficient combustion of air fuel mixture.

Digital- Since the spark generation will be initiated by a microchip. Twin- Since two spark plugs will be used. Spark ignit ion- Since the ignition will be done via a spark. How to Find, Ductile-Brittle Transition Temperature in Metals?


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The point at which the fracture energy passes below a pre-determined point for a standard Impact tests. DBTis important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter onimpact instead of bending or deforming.

What is the importance of Thermodynamics?All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is veryimportant for the mechanical engineers.

What is the difference between P11 and P12 Pipes?

P11 the chromium molybdenum composition that is 1% ofchromium and 1/4% of molybdenumP12 the chromium molybdenum composition that is 1% ofchromium and 2% of molybdenum

State difference between AnitiFriction Bearing and Journal Bearing?Generally, journal bearings have higher friction force, consume higher energy and release more heat, but theyhave larger contact surface, so normally used in low speed high load applications. In anti friction bearingsfriction is less. One object just rolls over each other.

What is the difference between Technology and Engineering?Engineering is application of science. Technology shows various methods of Engineering. A bridge can bemade by using beams to bear the load,by an arc or by hanging in a cable; all shows different technology butcomes under civil engineering and science applied is laws of force/load distribution.

How to Measure Temperature in Wet Bulb Thermometer?Wet bulb temperature is measured in a wet bulb thermometer by covering the bulb with a wick and wetting itwith water. It corresponds to the dew point temperature and relative humidity.

What are the Advantages and Disadvantages of using LPG in Car?Advantages1. Complete combustion2. Fuel saving3. Homogenous combustionDisadvantages1. As complete combustion is occurring ,more heat liberated,not advised for long journey, engine will be over

heated2. Installation is difficult3. Reduce engine life efficiency

What is the difference between Speed and Economic Speed?The rated speed tells us about the maximum speed which can be achieved by a vehicle or some other

machine but the economical speed means the speed limit at which the machine works efficiently with leastconsumption of fuel.eg-in normal bikes(not racing),the max.speed limit shown on speedometer is upto 120kmph but companies always advice their customers to drive such bikes at around 60 kmph to have maximummileage.

What is Powder Technology?

Powder technology is one of the ways of making bearing material. In this method metals like bronze, Al, Feare mixed and compressed to make an alloy.

State the difference between Unilateral and Bilateral Tolerance?A unilateral tolerance is tolerance in which variation is permitted only in one direction from the specifieddirection.e.g. 1800 +0.000/-0.060Bilateral tolerance is tolerance in which variation is permitted in both direction from the specified direction.e.g1800 +0.060/-0.060

What is the abbreviation of welding rod 7018?7018 =70=tensile strength 70000psi


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1= welding position8=current flux

What is difference between Welding and Brazing?In Welding concentrated heat (high temperature) is applied at the joint of metal and fuse together.In Brazinginvolves significantly lower temperatures and does not entail the melting of base metals. Instead, afiller metal is melted and forced to flow into the joint through capillary action.

Which has more Efficiency Diesel Engine or Petrol Engine?

Diesel engine has the better efficiency out of two.

What is Difference between stamina and strength?Strength is capability over a short length of time and Stamina is the ability to keep going continuously.

What is Hydrostatic System?Hydrostatics is the study of fluid bodies that are at rest moving sufficiently slowly so there is no relative motiobetween adjacent parts of the body. For hydrostatic situations there are no shear stresses, there are onlypressure forces that act perpendicular to any surface.Its a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor anmotor gives return energy to pump supply.

What is Cotter joint?A cotter joint is used to connect rigidly two co-axial rods or bars which are subjected to axial tensile orcompressive forces. Here shaft is locked in place by a smaller pin that passes through the side of the lug andpartly or completely through the shaft itself. This locking pin is named as cotter.

How is the excess discharge pressure prevented?Discharge pressure prevented by a pressurized spike cushion. Here the system employs a pressurizedcushion of air and a two o-ring piston, which permanently separates this air cushion from the water system.When the valve closes and the water flow is suddenly stopped, the pressure spike pushes the piston up thearrester chamber against the pressurized cushion of air. The air cushion in the arrester reacts instantly,absorbing the pressure spike that causes water hammer.

What is the difference between Strainer and Fitler?Strainer for coarse size, Filter is more accurate than Strainer.

What is the position of Piston Ring?In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gabelow the neck.

Why Deareator are placed at Hieght, In Thermal Power Plant?To build a Very high pressure and the temperature for a boiler feed water pump and it discharge high pressurwater to the boiler.

And to provide the required Net Positive Suction Head (NPSH) for the BFW pump and to serve as a storagetank to ensure a continuous supply of feed water during rapid changes in BFP.

What is meanst by One Tonn Air-Conditioner?1 ton refrigeration means 210 kJ/min extracts heat from thesystem.

State 1st Law of Thermodynamics?HEAT AND MECHANICAL WORK ARE MUTUALLY CONVERTABLE. ENERGY CAN BE CREATED NOR BDISTROYED BUT IT CAN BETRANSFERED FROM ONE FORM TO ANOTHER FORM.

If you heat a steel pipe with the hole at center, does heat affects the hole diameter?It gets bigger.

Why the Centrifugal Pump is called High Discharge pump?


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Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. Sothe liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of theimpeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So itdischarges the liquid in high rate. It is given in the following formulae:

Centrifugal force F= (M*V2)/R.Where,M-MassV-VelocityR-Radius

How Cavitation can be eliminated by Pump?Cavitation means bubbles are forming in the liquid. To avoid Cavitation, we have to increase the Pump size to One or Two Inch;To increase the pressure of the Suction Head, or Decrease the Pump Speed.

Why Cavitation will occur in Centrifugal Pump and not in Displacement Pump?The formation of cavities (or bubbles) is induced by flow separation, or non-uniform flow velocities, inside apump casing. In centrifugal pumps the eye of the pump impeller is smaller than the flow area of pipe. Thisdecrease in flow area of pump results in increase in flow rate. So pressure drop happened between pumpsuction and the vanes of the impeller. Here air bubbles or cavities are formed because of liquid vapour due to

increase in temperature in impeller. This air bubbles are transmitted to pump which forms cavitation.

Which Pump is more Efficient Centrifugal Pump or Reciprocating Pump?Centrifugal pump. Because flow rate is higher compared to reciprocating pump. Flow is smooth and it requireless space to install. Lower initial cost and lower maintenance cost.

Why Centrifugal Pump is not called as a Positive Displacement Type of Pump?The centrifugal has varying flow depending on pressure or head, whereas the Positive Displacement pump hamore or less constant flow regardless of pressure.Likewise viscosity is constant for positive displacement pump where centrifugal pump have up and down valubecause the higher viscosity liquids fill the clearances of the pump causing a higher volumetric efficiency.When there is a viscosity change in supply there is also greater loss in the system. This means change in

pump flow affected by the pressure change.One more example is, positive displacement pump has more or less constant efficiency, where centrifugalpump has varying efficiency rate.

Why Entropy decreases with increase in temperature?ds=dQ/T Entropy is inversely proportional to the temperature so, as temp. Increases, entropy decreases.

Why different types of sound are produced in different bikes, though they run on SI Engines? Engine specifications are different in different manufactures like as Bore Diameter (CC), Ignition timing. Alsothe exhaust passage takes more responsible for sound.

How much Watt means 1Hp?

746.2 Watt

Explain Bicycle Rear Wheel Sprocket working?Rear wheel sprocket works under the principle of ratchet and pawl.

Definition of Octane Number and Cetane Number?Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octanand h-heptane. It is the measure of rating of SI engine.Cetane No.- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetaneand alpha methyl naphthalene. It is the measure of rating of CI engine.

Which Mechanism is used in Automobile gearing System?


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Differential mechanism

When Crude Oil is Heated, Which Hydro Carbon comes first? Natural gas (Gasoline) at 20 Celsius

How to calculate Bearing number ti Diameter of the inner and outer? Divide the shaft diameter size by 5, it will give last two digit of the bearing no. and according to type of load whave to choose the type of bearing and that will give prior number of the bearing.

The Fatigue life of a part can be improved by?Improving the surface finish by Polishing & providing residual stress by Shot peening.

What happens if gasoline is used in a Diesel Engine, Siesel Engine will work?No, It will not work, as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to 22.Thus on such high compression, gasoline gets highly compressed & it may blast.

Poissons Ratio is Higher in, Rubber/Steel/Wood?When a material is compressed in one direction, it usuallytends to expand in the other two directionsperpendicular tothe direction of compression. This phenomenon is called thePoisson effect. Poissons ratio ismeasure of the Poisson effect.For rubber = 0.5

For steel = 0.288For wood < 0.2Thus Poissons ratio is higher in RUBBER.

Definit ion of Octane numb er & Cetane number

Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octanand h-heptane. It is the measure of rating of SI engine.Cetane No.- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetaneand alpha methyl naphthalene. It is the measure of rating of CI engine.

What is impo rtant to remember about radial bearings?

A turbine rotor is supported by two radial bearings, one on each end of the steam cylinder. These bearings

must be accurately aligned to maintain the close clearance between the shaft and the shaft seals, and betweethe rotor and the casing. If excessive bearing wear lowers the he rotor, great harm can be done to the turbine

How many governors are needed for safe turbine operation? Why?

Two independent governors are needed for safe turbine operation. One is an over speed or emergency tripthat shuts off the steam at 10 percent above running speed (maximum speed). The second, or main governousually controls speed at a constant rate; however, many applications have variable speed control.

How is a fly bal l governor used with a hydraul ic con trol?

As the turbine speeds up, the weights are moved outward by centrifugal force, causing linkage to open a pilovalve that admits and releases oil on either side of a piston or on one side of a spring-loaded piston. Themovement of the piston controls the steam valves.

What is meant by c ri t ical speed?

It is the speed at which the machine vibrates most violently. It is due to many causes, such as imbalance orharmonic vibrations set up by the entire machine. To minimize damage, the turbine should be hurried throughthe known critical speed as rapidly as possible. (Caution, be sure the vibration is caused by critical speed andnot by some other trouble).

How is oi l pressure maintained when start ing or stoppin g a medium-sized turbine?

An auxiliary pump is provided to maintain oil pressure. Some auxiliary pumps are turned by a hand crank;others are motor-driven. This pump is used when the integral pump is running too slowly to provide pressure,as when starting or securing a medium-sized turbine.


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Besides lubricat ion, what are two functions of lub ricat ing oi l in some turbines?

In larger units, lube oil cools the bearings by carrying off heat to the oil coolers. Lube oil in some turbines alsoacts as a hydraulic fluid to operate the governor speed-control system.

Do you stop c ool ing-water f low throu gh a steam cond enser as soon as the turbine is slopped?

You should keep the cooling water circulating for about 15 mill or more so that the condenser has a chance tocool down gradually and evenly. Be sure to have cooling water flowing through the condenser before startingup in order to prevent live steam from entering the condenser unless it is cooled. Overheating can causesevere leaks and other headaches.

How can the deposits be remo ved?

Water soluble deposits may be washed off with condensate or wet steam.Water insoluble deposits are removed mechanically after dismantling the turbine.Experience shows that water soluble deposits are embedded in layers of water-insoluble deposits. And whenthe washing process is carried out, water soluble parts of the deposit dissolve away leaving a loose, friableskeleton of water-insoluble deposits which then break loose and wash away.

How c an the fat igue damage on hig h-pressure blades be corrected?

Fatigue-damage on high-pressure blades arises due to vibration induced by partial-arc admission. This can bcorrected by switching over to full arc admission technique.

Can anybody please provide any link to calculate force required to bend a metal sheet into pipe? ordescribe how is it calculated?It depends upon the thickness of sheet and required diameter to be formed from the sheet.

A bearing is designated as 6205 , what is its bore diameter:Generally for bearing bore diameter is 5 times the last number in its designation i.e. for designation 6205, Bordiameter should be 25

where half nut is usethe half hut is use in lathe .in this half nut mechanism is engaged during the thread cutting operation.and itconnect carriage and lead screw.it having 2 portion one half is fixed and one movable.

why the rail in form of I-beam?Its flexural rigidity is high and its cross section consume low metal.

what is difference between pressure and stress?When the force or load acting on the fluid(pneumatic or hydraulic)per unit area is known as PRESSURE.. itspurely subjected to fluids..when the force or load acting on the object(solid) within the elastic limit of an object create internal resistanceto resist the apply load. that internal resistance is known as STRAIN for per unit area of that object.. Its mainlysubjected to solids

Is there any rake angle in blade which is used to shave the beard?it consists of negative rake angle.

stress strain diagram for fluidParallel line horizontal to stress axis

Whats the range of poisons ratio of a stable material?Theoretical values are -1 to 0.5Practical values are 0 to 0.5

what is the difference between limit of proportionality and elastic limitUp to the limit of proportionality stress is directly proportional to strain, follows hooks law, elastic limit is limit felasticity of material.


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What is the difference between Fan and Blower?Fan is an air pushing device. Either Axial or Centrifugal type systems are used to move the air in low pressureIt is rotated by a motor separately.When the fan is a housing of blades and motor, then it called as Blower. It directs the air in a single path withhigh pressure.

What is Heat Rate of Power Plant?Heat rate is a measure of the turbine efficiency. It is determined from the total energy input supplied to theTurbine divided by the electrical energy output

What is Hydrodynamic Cavitation?Hydrodynamic cavitation describes the process of vaporization in a constrained channel at a specific velocityBubble generation and Bubble implosion which occurs in a flowing liquid as a result of a decrease andsubsequent increase in pressure.

What is Difference between Hardness and Toughness?Toughness is the ability of a material to absorb energy.Hardness is the ability of a material to withstand wear.

What is the hottest part of Refrigerant in Refrigeration?Compressor

What does F.O.F Stand for Piping Design?Face of Flange, The F.O.F (Raised face and Flat face) is used to know the accurate dimension of the flange iorder to avoid the minute errors in measurement in case of vertical or horizontal pipe lines.

Where Multi stage Pump is Used?Pressure washing of Aircraft, Trains, Boats and Road vehicles as well as Spray washing of industrial parts anElectronic components.

What does pump develop:- (a) Flow (b) PressureA pump does not create pressure, it only creates flow. Pressure is a measurement of the resistance to flow.

How to measure temperature of Bearing?Normally the temperature range from 80 degree to 110 degree Celsius. So the following temperaturemeasurement devices are used. Dial Type Bearing Temperature Detector Stator Winding Temperature Detector Resistance Bearing Temperature Detector (Bearing RTD) Specialized in Pin type RTD

Difference between Performance and Efficiency?The accomplishment of a given task measured against preset known standards of accuracy, completeness,cost, and speed is called as Performance.Efficiency is defined as the input given and the work obtained from that input like money, time, labour etc. Its

the main factor of productivity.

What is Sentinel Relief Valve?Its a special type valve system. The valve will open when exhaust casing pressure is excessive (high). Thevalve warns the operator only; it is not intended to relieve the casing pressure.

What is the difference between Specification,Codes, Standards?Specification is describing properties of any type of materials.Code is procedure of acceptance and rejection criteria.Standard is accepted values and compare other with it.

Which is heavier 1kg Cotton or 1kg Iron?


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Both of them have same weight.

What is Auto Dosing?Auto dosing is an automated system of feeding the equipment with liquid products. It is the ideal way to ensuthe correct calibrated dose at the right time every time in auto.

What is the difference between Sudden Force and Impact Force? An impact is a high force or shock applied over a short time period when two or more bodies collide.A force which applies on the body (material) suddenly is known as sudden force.

What is Geyser Pressure Valve?To release the pressure created inside due to evaporation of water.

What is difference between Corrective actions and Preventive actions?Corrective actions are taken on discrepancies noticed during inspection of products/documents/processwhereas preventive actions are taken to eliminate the possibility ofdiscrepancy in future.

How do you know air is fully saturated?In its Dew point. (100% relative humidity condition)

What is the function of scoop in BFP (Boiler Feed water pump) in Thermal Power Station?

The Function of Scoop tube is regulating the varying amount of oil level in the coupling during operation ofinfinite variable speed.

What is Operating Pressure?The amount of pressure nearest the point of performing work at the output end of a pneumatic system. Thesystem operating pressure is used to specify the capability of valves and actuators

what is HVAC?Heat ventilation Air Condition

Why Isometric View Look Like 3D?In isometric view,we take angle of 30 degree with reference line. so we look from any side we can observe

three views of object with reduced scale. hence,isometric view is 3D.

What Is Difference Between Welding and Brazing?Ans.Welding is a process used to join to similarmetals,whereas brazing is preferred to join to dissimilar metals,In welding molten metal is achieved throughResistance ( electrical circuit used) where as in brazing heating process is used to melt the filler material.

What Are The Resource and Equipment For Measurement and How We Can Defined Measurement? scale. gauges Slip gauge, Wire gauge, Snap gauge. Indicators- Dial Inductor.

On Which Part Of The Flywheel Energy Will Get Be Stored?VanesThe Flywheel Ia A Ring Type Element Mounted On Top Of Crank Shaft. The Energy stored In that Ring Which

Is Flexible And compact And Expand As Per The Load....

How Much Fuel Is Consumed On Full For A 500KVA Diesel Generator In One Hour.Its Depend Upon The Engine Performance Approximately 85 Liters Per Hour.

We Can Conduct The Two Test For Pressure Vessels i.e. HYDRO and Pneumatic. Practically WhichOne Is Danger?The more danger is in pneumatic test.This is bcoz the volume of air going insides the tank is more as compato liquid which cause the shock wave aftertank blast i.e. in fail condition.Example: You can consider a case of fire works. Small body there is no liquidonly shock wave generated by air. You can feel that wave.But is liquid wave propagation is much less.


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What Is The Difference Between Pipe And Tube?long hollow material with capacity to bent at any point is called tube.while pipe has no capacity to bend wehave to use elbow to bend it.

A pipe is a vessel a tube is structural. A pipe is measured ID a tube is measured OD. tube will have aconsistent OD and its ID will change. Engineers see tubes and pipes with different eyes. A tube is structural.By having a consistent OD they can vary wall thickness,changing the ID, to increase strength. Because they are consistent OD, they have predictable characteristics

As We Know That Today Vehicles Coming In Market Without Carburetor. In This Situation How Does

The Engine Work.Instead of carburetor, a multifunctioning fuel injector is used in order to increase the efficiency. instead ofcarburetors nowadays high technology fuel injector are used

Why We Can Not Put Gas Kit In Diesel Vehicle. Please Give The Reason In Detail.It is because diesel engines are designed to take high viscous fuel like diesel only .Also they have highcompression ratio which elevate the temp. of the combustion chamber tremendously so if any petrol or LPGgas is injected in it will lead to precombustion of fuel and we will not get desired power stroke.

What is Function Of accumulator In Hyd. Machine?Accumulator Nothing But To Store The Energy In The Form Of Pressure And Flow Which Supply To SystemIt Is a Hydraulic m/c Which Stores Pressure Energy Of Fluid And Supply It To Other m/c. e.g. Hydraulic Crane

Lift.Accumulator Stores The Energy and Supplies to System Parts.

What Is Compressor?Compressor Is The Device To Compress The atmospheric air, Liquid,Gases To Use For Different Works.Compressor Is A Device Which Is Used For Obtaining The Required Compression Ratio Of Working Fluid asPer Different Work Area.Compressor Is A Device Which Pressurize The Atmospheric Air To Use A specific Work Load.

What Is The Function Of A Different In Vehicles?It Is Used To Provide Differential Speed at The Rear Wheel While Turning. Due To differential The Outer ReaWheel Is Moved Faster than the Inner.

When Eating Ice Cream, Why The spoon Of Wooden Material Is Always Straight And Plastic Spoon IsAlways Convex in Shape?Because In Wooden Material, There Is Greatest Amount Of Methyl Alcohol In Which H-C Bond Occurs..IceCream Means Water Of One Type..Hence The Wooden spoon Is Able To Hold The Ice Cream Without ConvShape..Unlikely In Plastic.....

What Is The Difference Between air-Conditioner and Cooler?Air Cooler Deals With Only Circulating Cool air Irrespective Of Heat Loads In Room....Whereas AC Is A System Which Deals With Maintaining Temperature, Humidity, Quality(Purity) And circulatioOf Air In The Room Taking Into Account The Heat Loads Of The System...

Why are Head Gaskets blown?Normally head gasket blows, when the engine overheats and they can also blow from incorrect installation orpoor design. Head gaskets expand and contract according to engine temperature, these cycles may happenafter a long period of time, causes the gasket to fail. If youre replacing the gasket, check the engine block, anhead for warping. Follow proper cleaning and torque specifications during assembly.

What is the difference between a Fence and a Wall?A fence is either more temporary or constructed from materials, other than concrete, stone or brick.

What is the Difference between a Humidifier and Vaporizer?The basic difference between humidifiers and vaporizers is that humidifiers disperse cool mist into the air, andvaporizers heat the water to disperse hot steam. Humidifiers are normally used in cooler climates, when due t


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the usage of heater, the air in the house becomes too dry for comfort and also, it becomes very difficult tobreathe. Humidifiers release cool moisture droplets into the air.Vaporizers also help in moistening the dry air in the house, but vaporizers release hot vapour into the air.There is a heating element in the vaporizers, which help in releasing steam. Vaporizers heat the water andthen release vapours.The basic difference between them is that one emits cold vapours, while the other one emits hot vapours.

What is the Difference between a Generator and Inverter?An inverter is only effective if there is already a source of electrical energy. It cannot generate its own. It can

simply convert electrical energy that is already there. On the other hand, a traditional generator cannot makeAC current into DC current.

What is the Difference between Quantitative and Qualitative Research?Quantitative research involves gathering data that is absolute, such as numerical data, so that it can beexamined in as unbiased a manner as possible.Qualitative research may yield stories, or pictures, or descriptions of feelings and emotions. The interpretationgiven by research subjects are given weight in qualitative research, so there is no seeking to limit their bias. Athe same time, researchers tend to become more emotionally attached to qualitative research, and so theirown bias may also play heavily into the results.

Difference between Absorption and Adsorption In absorption, one substance (matter or energy) is taken into another substance. But in adsorption only thesurface level interactions are taking place.

Difference between Liquid and Aqueous Liquid is a state of matter, while aqueous is a special type of liquid formed by dissolving a compound in wate All aqueous solutions are liquids, but not all liquids are aqueous solutions

Difference between Gas and Vapour Vapour can turn back and forth into liquid and solid states but a gas cannot Gases cannot be see while vapours are visible Vapours settle down on ground while gases do not

Difference between Boiling Point and Melting Point- The melting point is a defined for solids when it transfers from solid state to liquid state.- The boiling point is defined for liquids for a state change from liquid to gas.- Boiling point is highly dependent on the external pressure whereas the melting point is independent of theexternal pressure.

Why is sound faster in warm air?The speed of sound in air cair = 331.3 + (0.66 x T) m/s, where T is the temperature in C.The speed of sound is proportional to gas temperature and inversely proportional to its molar mass.Sound is transferred by collisions of molecules. Therefore sound waves will travel faster on warm air becausecollisions of molecules of air in warm air is greater.

What is the difference between Pipe and Tube?Ex. Iron Pipe, Carbon Tube, Steel Tube etc. Tube is defined by Outer diameter and Wall thickness (OD and WT). While Pipe is defined by Inner diamete(ID).Example:2 inch pipe have 2.375 inch outer diameter, where 2 inch tube have same 2 inch outer diameter. Tube is easily shaped by bending, where Pipe needs some mechanical work to shape it. Tube is tight then Pipe. Tube is applicable to non cylindrical sections like Square and Rectangular.


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Is gate valve used for Throttling?Gate valves are not suitable for throttling because the control of flow is difficult for the valves design, and theflow of fluid slapping against a partially open gate can cause extensive damage to the valve.

Why is the Suction pipe of Vapour Compression Refrigeration system insulated?1. It prevents the suction line from sweating and dripping water inside the house.2. The insulation also prevents the suction line attracting heat from the outdoors on its way to the condensercoil.

How does Welding damage Eye sight?An Electric welding arc produces Ultraviolet light and the UV light (Sun burn) will damage the retina. Weldingshields or Goggles with the proper shade (Automatic shading) of lens is the best protection for welders.Light filtering curtains and reduced reflective surfaces help protect both welders and observers in the area.

Explain why BCC, FCC and CPH lattice packing and features of grain structure affect the Ductility andBrittleness of parent metallic materials?Ductility is the mechanical property of a material. (It is the materials ability to deform under the tensile stresswithout fracture). So it is depends on the atoms how they arranged in a lattice and its grain size. The ability toabsorb the energy of the impact and fracture resistance depends on the arrangement of the atoms in a latticeand features of grain structure.

Why do you have Truss Bridges?Truss bridges carry load in tension and compression rather than bending (Self weight + The weight of vehiclecrossing it + Wind loads). A truss has the ability to dissipate a load through the truss work. The beams areusually arranged in a repeated triangular pattern, since a triangle cannot be distorted by stress.

Why I-section beam is preferred for heavy loading?Cross sectional shape I, giving many benefits. It is very good for giving stiffness (less deformation on loading)and to withstand higher bending moments (as a result of heavy loading) on comparison with other cross-sectional shapes of same area. Also, it is very easy to manufacture. It will have more moment of inertia.

What is difference between Center of Mass and Center of Gravity?Both terms are same when gravity is uniform. When gravity is non-uniform following are the terms:

The center of mass is a point that acts as if all the mass was centered there (the mass on one side of the poinis equal to the mass on the opposite side). If supported at the center of mass, an object will be balanced undethe influence of gravity.The center of gravity is the point at which where the sum (vector) of the gravitational forces act on an objectwhich will be balanced on that point.

What is the difference between Center of Mass and Centroid?If the material composing a body is uniform or homogeneous, the density or specific weight will be constantthroughout the body, and then the centroid is the same as the center of gravity or center of mass.Centroid: Centroid is the point, where the whole area of plane is going to be act. It is valid only for 2D problemlike plane figures, square plate etc.The center of mass is a point that acts as if all the mass was centered there (the mass on one side of the poin

is equal to the mass on the OPPOSITE side). If supported at the center of mass, an object will be balancedunder the influence of gravity.

What are the differences between Weight and Mass?Mass is a measure of how much matter an object has. Mass is specified in Gram or Kilograms.Weight is a measure of how strongly gravity pulls on that matter. Force is measured in Newtons.F=m.gThus if you were to travel to the moon your weight would change because the pull of gravity is weaker therethan on Earth but, your mass would stay the same because you are still made up of the same amount ofmatter.


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What is the difference between Projectile motion and a Rocket motion?A projectile has no motor/rocket on it, so all of its momentum is given to it as it is launched. An example of aprojectile would be pen that you throw across a room.

A rocket or missile does have a motor/rocket on it so it can accelerate itself while moving and so resist otherforces such as gravity.In mechanics point of view projectile dont have any particular shape it is a point mass. Whereas rocket has aparticular shape and hence it has center of gravity situated at particular point on its body. Therefore rocketmotion comes under kinetics and projectile comes under kinematics.

What type of cooling used in High Voltage Transformer?The big transformers you find on power poles usually use oil as a dielectric insulator, in smaller HVtransformers, like the ones in TVs are usually filled with resin.

What is honing of Cylinder Liners?The honing equipment used has been manufactured by "Chris Marine". The head of the honing device consisof four synchronized stones. For the initial honing diamond stones are used to break up the hardened surfacein the scuffed areas. For the main honing very coarse and hard stones are used to produce a very desirablerough surface all over the liner.The advantage, especially for the 2-stroke engines, is possibility to save the liner after a seizure, scuffing orblow-by or even to eliminate the ovality of the liner. Another advantage is that it is possible to machine a rougliner wall to obtain a well oiled surface.

What is the difference between Speed and Velocity?Speed is scalar quantity and Velocity is a vector velocity has both speed and direction.Speed is expressed as distance moved (d) per unit of time(t). Speed is measured in the same physical units omeasurement as velocity, but does not contain an element of direction. Speed is thus the magnitudecomponent of velocity.

Difference between Yield Stress and Yield Strength?Stress is a measure of the load applied to a sample relative to a cross sectional area of the sample. Strength a quantification of the samples ability to carry a load. The terms "yield strength" and "yield stress" of a materiaare usually used interchangeably (correct or not). It is the stress which will just cause the material to plasticaldeform. If a material yields at 30,000 psi, the yield stress is 30,000 psi. If the part in question has a cross

sectional area of 2 square inches, the strength at yield would be 60,000 pounds, but usually we just say theyield strength is 30,000 psi.

What is the difference between Yield and Ultimate tensile strength?The yield strength is reached when the material becomes Non linear (that is non elastic) and takes apermanent set when load is released. Material stretches but does not break. Ultimate strength is when itbreaks and is higher than yield strength.

What is the difference between Flexural strength and Tensile strength?Flexural strength is resistance offered against bending. Tensile strength is resistance offered against tensileforce.

What is the difference between Shear and Tensile strength?Tensile Strength for a Bolt is determined by applying a Force along it long axis. Shear Strength for a Bolt isdetermined by applying a Force across its diameter, as it would be loaded in a lug joint. Tensile strength isstrength in tension when pulling force is applied. And shear strength is strength against cutting force which isknown as shear force.

What is the difference between Tensile strength and Tensile modulus?Tensile strength is the ultimate capacity of the material to resist a tensile load regardless of deflection.Tensile modulus also known as Youngs modulus is a measure of the stiffness of an isotropic elastic materialIt is defined as the ratio of the uni-axial stress over the uni-axial strain. It is determined from the slope of astress-strain curve traced during tensile tests conducted on a sample of the material.


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1) Pitot tube is used for measurement of(a) Pressure(b) Temperature(c) Discharge(d) Velocity

Ans.: (d) Velocity

(2) Slow plastic deformation of material under constant stress is(a) Creep

(b) Fatigue(c) Endurance(d) Elastic deformation

Ans.: (a) Creep

(3) Mass balancing is done to(a) Avoid flutter(b) Increase bending stress(c) Reduce drag(d) Distributing mass on control surface

Ans.: (a) Avoid flutter

(4) Short columns are preferred over long columns from(a) Strength consideration(b) Buckling consideration(c) Weight consideration(d) None of the above

Ans.: (b) Buckling consideration

(5) Centre of pressure of an aerofoil with an increase of angle of attack will(a) Move forward(b) Move backward(c) Not move(d) None of the above

Ans.: (a) Move forward

(6) Thermal efficiency of a gas turbine plant as compared to diesel engine plant(a) Higher(b) Lower(c) Same(d) May be higher or lower

Ans.: (a) Higher

(7) A closed cycle gas turbine works on(a) Carnot cycle(b) Rankine cycle

(c) Joule cycle(d) Atkinson cycleAns.: (c) Joule cycle

(8) A bolt of uniform strength can be developed by(a) Keeping the core dia of threads equal to the dia of unthreaded portion of bolt(b) Keeping the core dia of threads smaller than the dia of unthreaded portion of bolt(c) Keeping the nominal dia of threads equal to the dia of unthreaded portion of bolt(d) None of the above

Ans.: (a) Keeping the core dia of threads equal to the dia of unthreaded portion of bolt


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(9) Stress concentration factor is defined as ratio of(a) Max stress to endurance limit(b) Nominal stress to endurance limit(c) Max stress to nominal stress(d) Nominal stress to max stress

Ans.: (c) Max stress to nominal stress

(10) Principle effect of humidity is(a) Corrosion

(b) Leaking from sealed enclosures(c) Permanent set of packing and gaskets(d) Differential contraction of metal parts

Ans.: (a) Corrosion

(11) Backlash is(a) Sum of the clearance of two gears(b) Mutual play between two gears(c) Amount by which the width of a tooth space exceeds the thickness of the engaging tooth on pitch ircle(d) Any of the above

Ans.: (c) Amount by which the width of a tooth space exceeds the thickness of the engaging tooth on pitch circle

(12) Teflon is used for bearings because of(a) Low co-efficient of friction(b) Better heat dissipation(c) Smaller space constraint(d) All of the above

Ans.: (a) Low co-efficient of friction

(13) When two elastic bodies collide with each other(a) Two bodies will momentarily come to rest after collision(b) The two bodies tend to compress & deform at the surface of contact(c) Two bodies begins to retain their original shape(d) All of the above

Ans.: (d) All of the above

(14) Antifriction bearings are(a) Thick lubricated bearing(b) Thin lubricated bearing(c) Ball & roller bearing(d) Plastic bearing

Ans.: (c) Ball & roller bearing

(15) What is Hertzian stress?(a) Tensile stress on inner surface of cylinder(b) Bending stress on two contact surface

(c) Contact stress on two contact surfaces(d) Shear stress on two contact surfacesAns.: (c) Contact stress on two contact surfaces

(16) Mohrs circle can be used to determine following stress on inclined surface(a) Principal stresses(b) Normal stresses(c) Maximum shear stresses(d) All of the above

Ans.: (a) Principal stresses

(17) What size of material required for making rolled threads?


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(a) Pitch diameter(b) Root diameter(c) Major diameter(d) None

Ans.: (a) Pitch diameter

1. What is mechanism?2. How Sap is useful for mechanical engineers?

3. What is Newton law, explain it.4. Explain the law of thermodynamics? What is a importance of it in a field of Mechanical Engineering?5. What is Hess law?6. What is PS?7. What is bearing? Explain types of it.8. What is the process flow diagram?9. What is a time and motion theory?10. Which is the hardest material on earth?11. One unit of BTU has how much number of Joules?12. Explain the procedure of operating a pump?13. What does a pump develop, Give reason to support your answer14. Pipe Explain the concept behind it

15. Explain the difference between pipe and a tube?16. Explain the formula of heal loss in a pipe.17. What kind of pipes are used for steam lines?18. Who invented a four stroke engine? According to you which one is more efficient Four stroke engineand a two stoke engine and why?19. What do you understand by the concept of 6 stroke engine? Explain how it work.20. Explain what is torque?21. What is the difference between torque and power?22. Explain why diesel engine called as high torque and petrol engine as high speed engine?23. Why heavy vehicles are made by diesel engine?24. How does length and initial angel effect period in a simple pendulum?25. Explain the difference between projectile motion and rocket motion?

26. According to you which one is stronger thick steel wire or thick steel wire and why?27. Between steel copper and brass,which conduct faster heat.28. Explain the types of sensor and their explanation.29. What all are the mineral needed to make a car?30. With the help of which instrument we can measure a speed in a car?31. Advantage and disadvantage of using LPG in a car?32. Why gas container are mostly in a cylindrical shape?33. Explain, why re-heater is used in gas turbine?34. How can a square section cut in lathe?35. how many types of suspension is used in automobiles?36. What is DTSI? Why it is used in motor bikes?37. What are the advantages of DTSI over normal engines?

38. What is meant by gear ratio?39. What is the ratio of specific heat of air?40. What is the percentage of carbon present in pig iron?

Q: Describe yourself.Q: Tell me about your educational background?Q: What do you know about the organization?Q: How would you do justice to the job?Q: What are your weaknesses?Q: What are your salary expectations for this job?Q: What are the projects you have ever undertaken?Q: What do you do in leisure?


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Q: Do you want to ask anything from us?Q: What are your hobbies?Q: Why do you want to go into this field?Q: Describe one of the technical problems you had to solve.Q: How would you develop yourself in this type of Structural Engineer role?Q: Do you have any experience in developing technical specifications?Q: What are the differences between vector and array?Q: What experience have you had in writing technical materials?Q: What is the thing you dislike the most in the world? Why?

Q: What does success mean to you?Q: How do you define failure?Q: How do you define arrogance? Are you arrogant?Q: What role are you ready to take in a group?Q: Who has been an inspiration for you?Q: What is more important to you, money or success?Q: What were some of your most important engineering achievements?Q: Can you name some engineers that you knew or worked with?Q: Can you describe how engineering generally has changed during your lifetime?Q: Why do you want this job?Q: Why do you want to work with this organization?Q: Where do you see yourself five years down the line?

Q: What are your strengths?Q: How do you pursue your hobbies?Q: What has been your greatest achievement?Q: What has been your greatest failure?Q: How do you take challenges?Q: Are you willing to work in shifts?Q: What is the thing you like the most in the world? Why?Q: What kind of person are you?Q: Rate yourself on a scale of 10.Q: Why did you choose _________ as your major/subjects?Q: Are you willing to travel?Q: Why are you leaving the organization you work for?

Q: How much time do you need to join the organization?Q: Are you aggressive?Q: What makes you a good manager?Q: What motivates you the most?Q: What skills and abilities do you have?Q: Is there anything you want to ask?Q: Design a four-input NAND gate using only two-input NAND gates.Q: What experience have you had in working with field forces?Q: Tell us about your experience with computer-aided design software.Q: Where were your early contributions in your engineering work planning, design, construction,operation, writing, teaching, and research?General Questions for Civil Engineers

Q: According to you, what is the best design for building bridges?Q: What are all the new civil construction materials and concepts?Q: What is softsoil?Q: Explain your project management?Q: What are the CAD software versions you have used?Q: What are some of the different ways to lay a foundation?Q: Why is a manhole round?Q: What is earth?General Questions for Mechanical EngineersQ: Explain about power technology?Q: How is SAP useful for mechanical engineers?Q: What are the different types of bearings? What are different types of rivets?


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Q: What is the applicability of mechanical engineering in the industry?Q: Explain Newtons Laws.Q: How is a factor of safety used in design?Q: Interpret a Stress vs. Strain Curve.Q: What types of equations or theories would be used in Static Failure?Q: What types of equations would be used in Fatigue Failure?Q: Which one is more efficient a four stroke engine or a two stroke? Why?

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