Top 30 Job Interview Questions and Answers for Mechanical Engineering

 Here are frequently asked mechanical engineering interview questions for freshers as well as experienced engineering candidates.

Top 30 interview questions and answers;

 1. What are types of gears?

•  Spur Gear
•   Bevel Gear
•   Worm Gear
•   Gear Rack
•   Helical Gear
•   Screw Gear
•   Internal Gear

2. What do you mean by gear module?

The module describes the size of gear, A pair of gears can only mesh correctly if and when the base pitch is the same.

3. What do you mean by gear ratio?

The gear ratio is the ratio of the number of teeth in the gear to the number of teeth in the pinion being the smaller of the two gears in mesh.

                                             EX -:   Driven\ driving = 75\25 = 3\1 =3:1 

4. Why bearing are used?

The bearing are used to allow rotation or linear movement and to reduce friction between two objects, the ease of movement (rotary or linear) reduces friction and improves the speed and efficiency of the object.

5. Classification of pumps?

                                                             

6. What do you mean by pump head?

The pump head or discharge head of a water pump is a measure of the power of a pump, This statistic is measured in meters or feet and is calculated by placing a tube or pump discharge and measuring the maximum height to which it can pump.

7. What do you mean by annealing? 

Annealing is the process of heating any material above the recrystallization temperature increases the hardness and strength of material.

8. What do you understand by heat treatment?

it is an operation that involves heating and cooling prosses of metals to change its properties.

9. Define case hardening?

Case hardening is a method of making outer surface harder of the steel parts, It is done to use low carbon steel.

10. What is universal coupling?

Universal coupling is used to connect two shaft whose axes are inclined to each other, It consist of a pair of hinges , connected by a cross shaft.

11. What is centrifugal pump?

Centrifugal pump are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow.

12. What do you mean by multi-stage centrifugal pump?

Centrifugal pump having two or more than two impeller are called multi-stage centrifugal pump.

13. What is gearbox? and why it is used?

Gearbox is a mechanical device and is used to reduce the speed and increase torque output while in some cases it is used to increase the output rpm reduce torque like in automobile.

14. Which type of gear are used in multi-stage gearbox?

Helical gear are used in multi-stage gearbox.

15. Bearing housing is made up of which metal?

Cast iron.

16. Which bearing is also called as high speed bearing?

Ball bearing.

17. What is formula to calculate module in gear?

formula :-  module = pitch circle diameter (mm) / number of teeth

                                        M= d/T

18. Which type of gearbox is mostly used in conveyor belt?

Worm & Wheel type

19. What is least count of Vernier? 

Least count = 0.02mm or 1/50mm

20. What is lest count of screw gauge?

Lest count = 0.01 or 1/100mm

21. How many pulley are used in conveyor belt?

• Head pulley 
• Tail pulley
• 2 bend pulley
• Take up pulley
• snub pulley

22. Which type of  bearing is used in pulley of conveyor belt?

Spherical roller bearing with tapered bore.

23. What is density steel? 

7.8g/cm3 or 7800kg/m3              
  Density = mass/volume 

24. Which material is called solid lubricant?

Graphite is a solid lubricant.

25. What are the various type of bearing?

a. Sliding contact bearing 

1. Split sleeve bearing
2. slit sleeve bearing 
3. Solid sleeve bearing 

b. Rolling contact bearing 

1. Ball bearing 
2. Ball thrust bearing 
3. Roller bearing 
4. Taper roller bearing 
5. Roller thrust bearing
6. Needle bearing

26. Hydraulic system work on which principal ?

Pascal's law

27. What is engine?

A machine with moving parts that convert heat energy in to mechanical energy.

28. Classification of engine based on working cycle?

1. Two stroke engines                                                             

Four-stroke and two-stroke engines. In a four-stroke engine, the cycle is completed in four strokes of the piston or two revolutions of crankshaft whereas,

      2.  Four stoke engines 

Two-stroke engine, the cycle is completed in one revolution and two strokes, suction and exhaust.

29. Different between diesel engine and petrol engine?

Diesel engine 

• These engines work on the diesel cycle
• The fuel is mixed with air inside the cylinder 
• Ignition is achieved with the help of the hot, compressed air.
• High compression ratio
• These engines work with fuels that have low volatilities 
• Generally used in heavy vehicles such as truck and buses
• Relatively low fuel consumption 

Petrol engine 

• Work on the Otto cycle 
• Air and the fuel are mixed in a carburetor
• Fuel is ignited with an electric spark 
• Relatively low compression ratio
• Relatively low amounts of power are produced in a petrol engine 
• Highly volatile fuels are used in these internal combustion engines  
• Used in light vehicles such as motorcycle and car
• High fuel consumption 

30. What is Otto cycle?

The auto cycle is an ideal thermodynamic cycle that requires four strokes of the piston:

1. Induction 

2. Compression

3. Ignition 

4. Exhaust.

most petrol engines in automobiles work on this cycle.