# Latest Placement Papers in Mechanical

• WHAT IS THE DIFFERENCE BETWEEN RATED 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 LEAST CONSUMPTION OF FUEL.EG-IN NORMAL BIKES(NOT RACING),THE MAX.SPEED LIMIT SHOWN ON SPEEDOMETER IS UPTO 120 KMPH BUT COMPANIES ALWAYS ADVICE THEIR CUSTOMERS TO DRIVE SUCH BIKES AT AROUND 60 KMPH TO HAVE MAXIMUM MILEAGE.

• 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 are the causes of main engine black smoke?

There is many cause of black smoke.

1.is improper mixture of fuel supply by carburetor like very rich mixture so the fuel improper burn.

2. it is when piston or piston ring is fail so back side cooling oil release in combustion chamber it cause black smoke.

3.improper ignition system like not sufficient time of pressure rise delay period .

• how cooling tower height selected?

The Function of a cooling tower is to cool the water coming from condenser.The water coming from condenser is hot and it is sprayed in a cooling tower and a air coming out from bottom cool the water which is coming down.Outside air is cool and air in inside the cooling tower is hot due to humidity.So there is a density difference between outside and inside air which caused pressure difference.

Pr Difference = g x H x ( density difference)

Where,

H = Height of chimney

Pr Difference = Pr Difference so that air can flow to cooling tower from outside

• How does axial thrust balance in multistage pump?

A BALANCING LINE FROM DISCHARGE END IS CONNECTED TO SUCTIONSIDE TO BALANCE AXIAL THRUST.

• how to calculate the boiler efficiency?any formula is there?

boiler efficiency= (heat transferred to feed water inconverting it to steam)/(heat released by completecombustion of fuel)

n(eta)= Mass of steam * (h- H(water))/(mass of fuel *calorific value fuel)

• What is the significance of torque(in N-m) given in the engine specification

it give the moment about any point or simple rotation.

• what is the exact requirement of priming?

priming is done in pumps to remove the entrapped air from the suction pipe thus aiding in smooth operation and avoiding in excess load on the pump.

• What is the use of a PULLEY?

transmission of power(force) in rotary form

• why does cycle rim don’t bend even in heavy loads?

Because of rubber tires. The load is distributed and its effect reduces i.e. tires absorbs heavy load and shocks with the support of steel rim.

The rim has many spokes. The spokes distribute the load equally and the rubber tires absorb more than half of the load.

• How tonnage can be controlled in PLC base hydraulic press

custom integration of press interlocks to interfacing with other parts of the hydraulic press line such as the feeder or transfer systems.

• Water circulation in a thermo syphon cooling system is caused by (choose the right one)
1. Conduction currents
2. A belt driven water impeller
3. A gear driven water pump
4. The change density of the water

2. A belt driven water impeller

Reason:

Water circulation in a thermo syphon cooling system is caused by a belt driven water impeller. The main advantages of the system are its simplicity and automatic circulation of water. There is no need of large flow rate of water particularly for the engines.

• What is BHP?

Brake horsepower is the amount of work generated by a motor under ideal conditions. This work is calculated without the consideration of effects of any auxiliary component, that may slow down the actual speed of the motor. Brake horsepower is measured within the engines output shaft and was originally designed to calculate and compare the output of steam engines.

As per the conventions, 1 BHP equals to:

• 745.5 watts
• 1.01389 ps
• 33,000 ft lbf/min
• 42.2 BTU/min

# Mechanical Engineer Job Interview Questions

• Different between technology & engineering?

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

• how a diesel engine works in generator?

Diesel engine is a prime mover,for a generator,pump,and for vehicles etc.generator is connected to engine by shaft.mostly in thermal power plat ,there is an engine is used to drive generator to generate power.

• WHAT IS THE OTHER NAME OF MICROMETER & VERNIER CALLIPER

Micrometer’s other name is Screw Gauze & Vernier caliper’s other name is slide caliper.

• What is flashpoint?

Flash point: the lowest temperature at which the vapor of a combustible liquid can be ignited in air.

• what is basic difference between impulse turbine and reaction turbine

In impulse turbine, jet is used to create impulse on blades which rotates the turbine and in reaction turbine, no jet
is used pressure energy is converted into kinetic energy.

In impulse turbine fluid enter& leave with same energy ,but in reaction turbine fluid enter with pressure energy &
leaves with kinetic energy

In impulse turbine all the pressure drops in nozzle only & in reaction turbine pressure drops both fixed & moving

• What is the need for drafting?

Drafting is the allowance give to casting process.it also used to remove the casting from mould without damage of
corners.

internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. British Standard Whitworth (BSW) is one of a number of imperial unit based screw thread standards which use the same bolt heads and nut hexagonal sizes.

• What is refrigerant?

Any substance that transfers heat from one place to another,
creating a cooling effect. water is the refrigerant in absorption machines.

• The amount of carbon present in Cast Iron

Carbon is basically present in the form of cementite in cast iron.Its percentage lies in the range of 2.03-6.67(% by weight of cementite for Cast Iron.If the amount is less than the above range than it is stainless steel.

• What are the loads considered when designing the Nut and Bolts?

• The main purpose of the fan of a liquid cooling system for an engine is to
1. Disperse engine fumes
2. Cool the external surfaces of the engine
3. Pump hot air over the cold cooling water
4. Give an airflow when the vehicle speed is low

4. Give an airflow when the vehicle speed is low

Reason:

Fan is a forced cooling system. The fan throws air on the liquid continuously which forcibly dissipate the heat gained by the liquid.

• What is the effect of reheat on rankine cycle?

1.Efficiency increases

2.Work output increases

3. both

4. none of these.