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Mechanical Interview Questions 15 contain questions about...

141. What is the purpose of scrapper ring?

142. What are the causes of main engine black smoke?

143. How cooling tower height selected?

144. How does axial thrust balance in multistage pump?

145. How to calculate the boiler efficiency? Any formula is there?

146. What is the exact requirement of priming?

147. What is the use of a PULLEY?

148. Why does cycle rim don’t bend even in heavy loads?

149. How tonnage can be controlled in PLC base hydraulic press?

150. What is BHP?

141. What is the purpose of scrapper ring?

scrap the excess lube oil from the cylinder walls.there by preventing oil from entering combustion zone.

142. What are the causes of main engine black smoke?

There is many cause of black smoke.

1.It 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 .

143. 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

144. How does axial thrust balance in multistage pump?

A balancing line from discharge end is connected to suctionside to balance axial thrust.

145. How to calculate the boiler efficiency? Any formula is there?

Boiler efficiency= (heat transferred to feed water in converting it to steam)/(heat released by complete combustion 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.

146. 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.

147. What is the use of a PULLEY?

transmission of power(force) in rotary form

148. 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.

149. How tonnage can be controlled in PLC base hydraulic press?

Custom integration of press interlocks to inter facing with other parts of the hydraulic press line such as the feeder or transfer systems.

150. 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