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Part -4 Most commonly asked Mechanical Interview Questions

Most commonly asked Mechanical Interview Questions with answer

 1.          What is Difference between stamina and strength?

 Ans.    Strength is capability over a short length of time and Stamina is the ability to keep going continuously.

2.          What is Hydro-static System?

 Ans.    Hydrostatics is the study of fluid bodies that are
  • At rest
  • Moving sufficient slowly so there is no relative motion between adjacent parts of the body
For hydrostatic situations
  • There are no shear stresses
  • There are only pressure forces that act perpendicular to any surface.
It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply.

3.          What is Cotter joint?

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

4.          How is the excess discharge pressure prevented?

 Ans.     Discharge pressure prevented by a pressurized spike cushion. Here the system employs a pressurized cushion 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 the arrester chamber against the pressurized cushion of air. The air cushion in the arrester reacts instantly, absorbing the pressure spike that causes water hammer.

5.          What is the difference between Strainer and Filter?

 Ans.     Strainer for coarse size, Filter is more accurate than Strainer.

6.          What is the position of Piston Ring?

 Ans.     In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck.

7.          Why Deaerator are placed at Height, In Thermal Power Plant?

 Ans.    To build a Very high pressure and the temperature for a boiler feed water pump and it discharge high pressure water to the boiler.
And to provide the required Net Positive Suction Head (NPSH) for the BFW pump and to serve as a storage tank to ensure a continuous supply of feed water during rapid changes in BFP.

8.          What is meant by One Tonn Air-Conditioner?

 Ans.     1 ton refrigeration means 210 kJ/min extracts heat from the system.

9.          State 1st Law of Thermodynamics?

 Ans.    Heat and mechanical work are mutually convertible. Energy can neither be created nor be destroyed but it can be transferred from one form to another.

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

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