Latest Mechanical Updates

01-Technical Interview questions-how to prepare for technical interview-job interview-getting a job

  • What is the Material composition in IBR tubes?

Carbon max………………… 0.10%

Manganese max……………. 0.60%

Nickel max…………………. 0.25%

Sulphur max………………… 0.050%

Phosphorus max…………….. 0.050%

  • What is the difference between P11 & P22 pipes?

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

P12 the chromium molybdenum composition that is 1% ofchromium and 2% of molybdenum

  • 1st law of Thermodynamics



  • Difference between Unilateral tolerance and Bilateral tolerance

A unilateral tolerance is tolerance in which variation is permitted only in one direction from the specified direction.e.g. 1800 +0.000/-0.060

Bilateral tolerance is tolerance in which variation is permitted in both direction from the specified direction.e.g. 1800 +0.060/-0.060

  • Why we need two angle of projections ( 1st angle and 3rd angle)? Cant we standardize to one.

Generally 1 St. angle followed in India and 3rd angle projection is used in European countries. In 1st and 3rd angle projections there is no overlapping of principal planes while drawing side and top views. but in 2nd and 4th angle projections the principal planes are overlapped while drawing top and side views. It results confusion in drawing. For this reason 1st and 3rd angle projections are used commonly.

  • During which of the following processes does heat rejection takesplace in carnot vapour cycles
    1. Constant volume
    2. Constant pressure
    3. Constant temperature
    4. Constant entrophy


Constant Temperature

  • What is the difference between Corrective actions and preventive actions?

Corrective actions are taken on discrepancies noticed duringinspection of products/documents/process whereas preventiveactions are taken to eliminate the possibility ofdiscrepancy in future.

  • What is the Shaft coupling and its types

It is used to join two shafts for transmission motion from one shaft to another shaft,it may be either flexible or rigid type.

Rigid coupling;(Muff coupling, Flange coupling, Marinecoupling, Oldham”s coupling)Flexible coupling;(Flexible bush pin coupling)

Oldham’s Coupling is used when axis of shaft are not aligned

Other types are:

loveys joy coupling

Spider coupling

Tyre coupling

Pin and bush coupling

Fluid coupling

Vulcan coupling

Flexible coupling

Universal coupling

Articulate joints

  • What is meant by One ton Air conditioner, how fast it cool a room.

1 ton refrigeration means 210 kJ/min extracts heat from thesystem.

  • Boyle’s law

Boyle’s law describes the inversely proportional relationship between the absolute pressure and volume of a gas.

  • When temperature increases the frequency of the tuning fork
    a. Increases
    b. Decreases
    c. Remain same
    d. Increases or decreases depending on the material

B. Decreases

  • What happens in the float chamber during the idling action of the fuel pump
    a. It remains empty
    b. It remains partially filled
    c. It remains filled
    d. None

C. It remains filled

During idling period, no petrol is drawn from the carburettor and the float inside the float chamber floats exerting pressure on the fluid as a result of which the inflow of the fuel to carburettor is stopped.

  • The exact analysis of viscous flow problems can be made by
    a. Euler’s equation
    b. Hagen poiseuille’s equation
    c. Continuity equation
    d. Navier-stroke’s equation

D. Navier – stroke’s equation

Latest Mechanical Interview Questions & Answers | Thermal Interview Q & A | Automobile Interview Q & A

01-Technical Interview questions-how to prepare for technical interview-job interview-getting a job

  • What happens if gasoline is used in a Diesel engine?Diesel 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.

  • Which Mechanism is used in Automobile gearing system

Differential mechanism

  • Why different types of sound are produced in different bikes though they say run on SI engine

Engine specifications are different in different manufactures like as Bore Diameter(CC), Ignition timing.Also the exhaust passage take more responsible for sound.

  • Why entropy decreases with the increase in temperature?

ds=dQ/TEntropy is inversely proportional to the temperature temp. increases,entropy decreases.

  • 1 hp how much watt?


  • How to calculate bearing number to diameter of the inner and outer

Divide the shaft diameter size by 5, it will give last two digitof the bearing no. and according to type of load we have tochose the type of bearing and that will give prior no. ofthe bearing.

  • Explain Bicycle rear wheel Sprocket working?

Rear wheel sprocket works under the principle of ratchet and pawl.

  • In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the
    1. Expansion valve to the evaporator
    2. Evaporator to the thermostat
    3. Condenser to the expansion valve
    4. Condenser to the evoparator


Exapansion valve to the evaporator


A capillary tube is the replacement of thermostatic valve and connects expansion valve to the evaporator

  • Definition of Octane number & Cetane number

Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and 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-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.

  • Poisons ratio is higher in (rubber/steel/wood)

When a material is compressed in one direction, it usuallytends to expand in the other two directions perpendicular tothe direction of compression. This phenomenon is called thePoisson effect. Poisson’s ratio is a measure of the Poisson effect.

For rubber = 0.5

For steel = 0.288

For wood < 0.2

Thus Poisson’s ratio is higher in RUBBER.

  • The Fatigue life of a part can be improved by ?

Improving the surface finish by Polishing & providing residual stress by Shot peening.

  • The commonly used material for insulator of spark plug is
    1. Bekelite
    2. Asbestos
    3. Alumina
    4. Copper


  1. Alumina
  • When crude oil heated Which Hydro carbon comes first?

Natural gas(Gasoline)… at 20 Celsius