Interview Question for Automobile Engineering - Part 03

Question No. 51
What is kingpin offset? State some of its application.
AnswerThe kingpin offset is the part, basically called as pivot used in the steering of the vehicles. This offset helps in rotating of the steering and thus it’s very useful in steering mechanism of the cars.
Applications: This is also used to measure scrub radius with the help of geometric parameters of wheel plane above and below ground level. It provides directional stability to the vehicles when it i combined with the caster.

Question No. 52
Explain the basic difference between BS2 and BS3 engine.
AnswerThe basic difference of BS2 and BS3 engines is the presence of catalytic converter. Catalytic converter is present in BS3 engine which helps in reducing the formation of HC and CO. While in BS2 engine, no catalytic converter is present which forms HC and CO. Thus in BS3 engine there is no emission of harmful CO and HC. The full form of BS is bharat stage, which is a standard of emission in India.

Question No. 53
In a tractor, how the hydrostatic propulsion systems work?
AnswerThis system is based on Pascal’s law. In a tractor the pressure is same, so the force given by the liquid to the surrounding is equal to the pressure × area. Thus, obeying the Pascal’s law hydrostatic propulsion system is designed, similarly small piston feels small force and the large piston feels larger area.

Question No. 54
Explain the reason that why the tyres are always black in color. Is this phenomena related to the heat conduction?
AnswerTyres color is black due to the proportion of carbon mixed in it during the vulcanization of the rubber, to make the tyre shear resistant. Without vulcanization tyres won't be able to bear the friction heat and stress of the road. Thus carbon is responsible for giving tyres the prominent black color. Adding of carbon prevents tyres from rapidly deteriorating because when ozone combines with the ultraviolet light from the sun. It attacks the polymer of the tyre.

Question No. 55
What is back compressor in engines?
AnswerBack compression means the compression capability of the engine. A diesel engine can compress at the ratio of 14:1 to as high as 25:1. Thus the higher compression leads to better efficiency of the engine. Thick black smoke is emitted when the engine’s compression is reduced which leads to the deformed head-gasket lead into crankcase.

Question No. 56
Why the plastic materials used in the screwdriver's handles?
AnswerDue to non-conducting nature of plastic, it is widely used for the electricity purposes. Moreover, plastic is cheap and strong so it is less prone to damage. Furthermore, plastic does not bend and does not slip from the users hands.

Question No. 57
Does diesel engine powered automobile use unit pump and unit injector?
AnswerIn the case of the engines powered by diesel fuel supply systems, unit pump & unit injector are operated by camshaft & thus pressure of injected fuel depends on engine speed. Whereas, in common rail systems it is independent of engine speed.

Question No. 58
What are MPFI and TPFC systems?
AnswerMPFI stands for Multi Point Fuel Injection. In this system fuel is injected into the intake ports which is situated just upstream of each cylinder’s intake valve. These systems are sequential systems, in which injection is timed to coincide with intake stroke of each cylinder.
TPFC stands for transient power fuel control system. In this type of systems constant choke carburettor is used. The salient feature of this carburettor is that it provides jerk less engine raise. In these systems, throttle valve creates vacuum which opens the slide which controls the air fuel ratio through a tapered jet.

Question No. 59
Why does a compression engine use high octane fuel?
AnswerThe property of a fuel, which describes how fuel will or will not self-ignite, is called the octane number or just octane. Engines with low compression ratios can use fuels with lower octane number, but high compression engines must use high-octane fuels to avoid self-ignition and knock.

Question No. 60
What is pitching in the suspension system?
AnswerPitching is a rocking action about a transverse axis through the vehicle, parallel to the ground. The front suspension moves out of phase with the rear, experiencing the rocking effect due to pitching.
What do you mean by Independent suspension?
Independent suspension refers to the mounting of the wheel on a separate axle, so that road shocks affect only the particular wheel.

Question No. 61
What is clutch drag?
AnswerWhen the clutch is not disengaging fully and provides some difficulty in changing the gears then this defect is called clutch drag.

Question No. 62
What is the cause of black smoke from the exhaust?
AnswerThere are various possible causes of black exhaust smoke, almost all of which should let you know that your engine is burning too much fuel. Check all of your vehicle's intake components, including your air filter, sensors, fuel injectors, and fuel-pressure regulator. One other cause could be a clogged fuel line.

Question No. 63
What type gear is used for sun gear?
AnswerMost commonly used gears as Sun gears are Spur gears and Helical gears. In some cases Epicyclic Gear trains with Bevel Gears are also used.

Question No. 64
Why don't auto-rickshaws have differential gears?
Answer Auto-Rikshaws have engine directly connected to rare end wheels. There is no need of differential gears.
But some Auto-Rikshaws are not driven by the engine directly instead they use a differential gear. The entire differential mechanism is inside the gearbox unlike other vehicles.

Question No. 65
Which type of gears is used in motorcycle gearbox?
AnswerSpur gears in sequential arrangement are used inside a gear box of a motorcycle. While chain and sprocket are engaged to transmit power from engine to the rear wheel.

Question No. 66
How many differential gears are used in a car?
AnswerThere is only one differential working in a car,  however in a differential 5 bevel gears are used,  one is mounted upon the shaft,  the 2 are mounted upon the 2 shafts connecting to the rear wheels, the other 2 gears are so arranged so that they mess with the gears upon the wheel shafts.

Question No. 67
Which Mechanism is used in Automobile gearing system?
AnswerDifferential mechanism

Question No. 68
1 hp is how much watt?

Question No. 69
Explain Bicycle rear wheel Sprocket working?
AnswerRear wheel sprocket works under the principle of ratchet and pawl.

Question No. 70
The Fatigue life of a part can be improved by?
AnswerImproving the surface finish by Polishing & providing residual stress by Shot peening.

Question No. 71
When crude oil heated Which Hydro carbon comes first?
AnswerNatural gas (Gasoline) at 20 degree Celsius

Question No. 72
What type of metal is used in a propeller?
AnswerAluminium, stainless steel, magnesium bronze, NIBRAL (nickel, brass, aluminium)

Question No. 73
What is more dangerous longitudinal stress or Hoop stress and why?
AnswerHoop stress is more dangerous than longitudinal stress, because the dangerous area coming under the hoop stress is circumferential, while in longitudinal, the axial area will come under dangerous area will be less than circumferential area. So the hoop stress is more dangerous than longitudinal stress.

Question No. 74
For the purpose of inflating car tyres, spray painting, etc. i.e. say a small workshop, what size of a compressor (CFM) is recommended? It will be generally for a hobby use and not commercial use?
AnswerSpray painting it is generally used for painting in a very smaller area of any part and where it is very hard to paint in a brush and to improve faster rate of painting, spray painting r used. Usually reciprocating compressor r used but size depends upon requirement.

Question No. 75
What is king pin offset?
AnswerA geometric parameter which is positive if the kingpin axis intersects the wheel plane at or below ground level, or is negative if the point of intersection is above ground level. Also called scrub radius.
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