Automobile Engineering Job Interview Questions and Answers for fresher and Experienced Automobile and Mechanical Engineers:
Question No. 01
What is
Automobile Engineering?
Answer: Automobile Engineering
is a branch of engineering which deals with designing, manufacturing and
operating automobiles. It is a segment of vehicle engineering which deals with
motorcycles, buses, trucks, etc. It includes mechanical, electrical,
electronic, software and safety elements.
Question
No. 02
How will you differentiate between two
stroke engine and four stroke engines?
Answer: 2-stroke piston engine
has an intake and an exhaust stroke. All air, fuel, and combustion products
must be moved in those 2 strokes. A 4-stroke engine has a separate stroke for
moving burned (or burning) and unburned mixtures - intake, compression,
expansion, and exhaust. Using 4-stroke results in cleaner emissions at the
expense of specific power.
Two stroke: For
each explosion in cylinder piston moves downwards and upwards (one complete
cycle) (Power stroke and Exhaust stroke).
Four stroke: for each explosion in cylinder piston moves down and upwards twice (two complete cycle) (Intake , compression, power, exhaust stroke.)
Four stroke is highly efficient than two stroke.
But two stroke is powerful than four stroke.
Four stroke: for each explosion in cylinder piston moves down and upwards twice (two complete cycle) (Intake , compression, power, exhaust stroke.)
Four stroke is highly efficient than two stroke.
But two stroke is powerful than four stroke.
Question
No. 03
What is the range of engine efficiency in
case of two stroke engine?
Answer: The two stroke engines
have very high range to be compared to the four stroke engines. Because power
stroke is generated every two revolution while in four stroke, power stroke is
generated every four revolutions.
Question
No. 04
Definition
of Octane number & Cetane number
Answer:
- Octane Number - 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 Number - 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.
Question No. 05
What do you understand by CC of engine?
Answer: The meaning of CC is
cubic centimeters. It represents the total volume of the engine cylinder. This
reflects that the engines with more CC can generate more powers than the other
engines. CC can also be related as inversely proportional to the fuel
consumption.
Question
No. 06
If we use gasoline in diesel engine, what will
happen?
Answer: Adding gasoline to the
diesel engine may blast off the engine. Compression ratio of the petrol engine
is 6 to 10 and diesel engine is 15 to 22. Thus gasoline will get very highly
compressed and might result in blast off engine.
Question
No. 07
Explain the significance of governor in
automobiles?
Answer: Governor is an important
component of automobile engine. It is used to regulate the main speed of engine
during the variations in loads. With the variations in the load, fuel supply
has to be maintained. This task is performed by the governor. In the case of
high load on the engine, speed decreases, hence fuel supply has to be increased
and similarly when load decreases then the fuel supply has to be decreased.
Question
No. 08
What is the use of hydrogen in automobile?
Answer: Low emissions.
Essentially no CO or HC in the exhaust as there is no carbon in the fuel. Most
exhaust would be H₂O and N₂ Fuel availability. There are a number of different
ways of making hydrogen, including electrolysis of water.
Question
No. 09
What is the use of Natural gas in
automobiles?
Answer:
- High octane number makes it very good S.I engine fuel
- Low engine emissions. Less aldehydes than with methanol
Question
No. 10
What is an automotive differential and how
does it work?
Answer: The automotive differential is designed to drive
a pair of wheels while allowing them to rotate at different speeds. In vehicles
without a differential, such as
karts, both driving wheels are forced to rotate at the same speed, usually on a
common axle driven by a simple chain-drive mechanism.
Question
No. 11
What is the working principle of
hydrostatic propulsion system in a tractor?
Answer: It depends on Pascal
law. As the pressure in the system is the same, the force that the fluid gives
to the surroundings is therefore equal to ‘pressure × area’. In such a way, a
small piston feels a small force and a large piston feels a large force
Question
No. 12
What is oil grade SAE stands for?
Answer: "SAE" stands
for "SOCIETY OF AUTOMOTIVE ENGINEERS" (USA).
Question
No. 13
By mixing
oil in fuel of four stroke bike will it damage engine, performance? If not than
what happen?
Answer: Yes, absolutely. It leads to higher wear and tear in cylinder
liners, piston and damage of the piston. It even leads to knocking and
detonation where abnormal combustion appears and dark smoke and harsh
sound will be produced by the engine.
Question
No. 14
Why are
car steering wheels round?
Answer:
- A steering wheel is round so that your hands locate in the same place regardless of the steering wheel's orientation.
- While turning / steering the car it is ergonomically the best design.
- Also as design is circle, there are no edges to hit while turning / steering is moving as the circle position remains the same.
- From Design view, it should be able to give uniform force i.e. torque, by varying the distance from center will vary the torque provided.
Question No. 15
How
Trains take turns, though there is no any differential?
Answer: Purpose of the
differential is to enable vehicles to take turn, by allowing both the wheel to
rotate with different speed. This is required when wheels, like in car, are
connected with same axle. Interestingly, wheel in trains are not connected with
the axle, they are independent and hence can take turns without ant
differential. This is same as how the bullock cart takes turns, without any
differential.
Question
No. 16
What is
the difference between BS2 & BS3 engine?
Answer: IN BS2 there is No catalytic converter to reduce formation of co
and HC whereas in BS3 catalytic converter is available to reduce the
formation of HC and CO. So less emission of HC and co will take place in
BS3
Question
No. 17
Why big
tyre used in rear of Tractors?
Answer: Tractors have big rear tires because, the larger the surface area of the
tractor's wheels touching the ground, the more pulling power you have.
Like how tractor pullers have large tires.
Another reason is that the tractor doesn't
have to operate at a higher speed to get the same ground speed with larger tires.
Gear ratios don't have to be as high b/c of the larger tires.
Question
No. 18
What will happen if someone adds oil to the
fuel of four stroke bike engine?
Answer: This will result in
damaging of the engine faster. Adding oil will lead to the higher wear and tear
of the cylinder liner, piston and damage to the piston. It will lead to
abnormal combustion and knocking and detonation. Dark smoke and abnormal sounds
will be generated by the engine. One should not mix oil with the fuel of four
stroke engine.
Question
No. 19
How air conditioners work in cars?
Answer: Air conditioners are
based on the principles of evaporation and condensation and then compression
and expansion. The hot air of the car is removed by the process of evaporation
and then the condensation of the evaporated air takes places which is then
further compressed by the compressor and then finally expanded to us in the form
of cold breeze. Somehow, Air conditioning reduces the average of the car, as
the energy is required to remove the hot air and then compression and
expansion.
Question
No. 20
Why
entropy decreases with the increase in temperature?
Answer: The relation is ds = dQ/T
Entropy is
inversely proportional to the temperature so as temperature increases, entropy
decreases.
Question
No. 21
What is SAE? Mention the importance of SAE
to the automobile domain.
Answer: SAE stands for society
of automotive engineers. This society is responsible for developing the
standards for the engineering of powered vehicles of all kind. The vehicles may
include car, boat, truck and even aircraft. SAE has developed standards for
ground vehicles and aerospace vehicles. SAE also encourages students of
engineering, technology, science and math’s disciplines. This society has been
publishing technical information since 1906.
Question
No. 22
How does the thermostat work?
Answer: When the engine is too
cold the thermostat closes the main valve, thus stopping the flow to the
radiator. When the engine is too hot, it opens the main valve for normal
circulation through the radiator.
Question
No. 23
Why
involute curve used in gear?
Answer:
- It’s smooth to drive the gear.
- In gears contact is only point, this type is curve take the more load than normal one
Question No. 24
What does it mean when your car emits white
smoke?
Answer: White smoke is a sign of a coolant leak as is milky brownish
oil. This could be due to bad head gasket or cracked block. Burning oil smoke is usually more bluish in
color. White smoke is
usually associated with a coolant leak, but burning oil can also look
like white smoke
Question
No. 25
What
happens if gasoline is used in a Diesel engine? Diesel engine will work?
Answer: 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.