Skip to main content

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 sucient 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.

See related more FAQs  <<<< Click Here >>>>



Popular posts from this blog

MAGNETIC PARTICLE EXAMINATION (M.P.I.)

MAGNETIC PARTICLE EXAMINATION (M.P.I.) INTRODUCTION This method is used for detecting cracks and other discontinuities open to surface or sub surface in ferromagnetic materials. Fine magnetic particles are applied to the surface of a part which has been suitably magnetized. The particles are attracted to regions of magnetic non-uniformity associated with defects and discontinuities, thus producing indication which are observed visually. PRINCIPLE When a piece of metal is placed in a magnetic field and the lines of magnetic flux get intersected by a discontinuity such as a crack or slag inclusion in a casting, magnetic poles are induced on either side of the discontinuity. The discontinuity causes an abrupt change in the path of magnetic flux flowing through the casting normal to the discontinuity, resulting a local flux leakage field and interfering with the magnetic lines of force. This local flux disturbance can be detected by its affect upon magnetic particles that collect o...

CHARPY V NOTCH IMPACT TEST

CHARPY V NOTCH IMPACT TEST Object : To determine the amount of energy absorbed in fracturing a standardized test piece at a specified temperature. Method : A machined, notched specimen is broken by one blow from a pendulum. Because scatter occurs in the results, at least three specimens are used to assess the joint represented. Testing is carried out at a temperature specified in the appropriate application standard. Reporting Results: Location and orientation of the notch.  Testing temperature. Energy absorbed in joules.  Description of fracture appearance. Location of any defects. The Charpy impact test, measured in joules, is an assessment of TOUGHNESS. Transition temperature (curve) in steel.

The Brinell Hardness Test

The Brinell Hardness Test The Brinell hardness test method consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope. The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation. The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained us...