Question
No. 26
What is the range of the engine efficiency
for two stroke engine? Why you don't see two stroke engines in car? What are
problem with two stroke engine?
Answer: The range of two stroke engine is too high
compare to the four stroke engine because of each revolution one power
in two stroke engine. I cannot see the 2 stroke engine in car. Power
loss is more.
Question
No. 27
What is
the formula for calculating BHP in SI units?
Answer: Boiler horse power (BHP) is a power unit used
for measuring the power output of boilers, widely used in the past, but now
confined to North America. The boiler horsepower conversion formula is as
follows.
1 Boiler Horsepower = 9,809.5 Watts
Question
No. 28
What is
the meaning of CC engine?
Answer: CC stands for Cubic centimeter. CC represents
the total volume of an engine cylinder. The engine which has more CC
can produce more power than others.
Question
No. 29
Why
freezer in the fridge is placed in top level?
Answer: Because
density of cold air is higher than warm air, hence it is placed at top. Cold
air comes downward & cool the bottom part.
Question
No. 30
Poisons
ratio is higher in (rubber/steel/wood)
Answer: When a
material is compressed in one direction, it usually tends to expand in the
other two directions perpendicular to the direction of compression. This
phenomenon is called the Poisson 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.
Question
No. 31
What type
of gears is used in small cars?
Answer: A gear in a
car is used mainly in the transmission system, the steering system and the
differential system. In the transmission system the gears used are
helical gears these provide better efficiency, better safety and durability at
high speeds, steering system uses rack and pinion type of gear
system. While differential uses bevel gears. As the torque is to be
transmitted perpendicularly.
Question
No. 32
How is
power generated from fuel?
Answer: Fuel
generates power by being burned, oxidized is the technical term. In the process
of burning, heat is released. The energy of the heat is used to do work.
Exactly what kind of work depends on what kind of energy absorbing device the
energy is put into.
Steam power can be generated by burning the fuel under a container with water in it and using the steam for some purpose.
Steam power can be generated by burning the fuel under a container with water in it and using the steam for some purpose.
Question
No. 33
What are
the different type’s sun gears and planet gears used in differential?
Answer: A
differential is a particular type of simple planetary gear train that has the
property that the angular velocity of its carrier is the average of the angular
velocities of its sun and annular gears. This is accomplished by packaging the
gear train so it has a fixed carrier train ratio R = -1, which means the gears
corresponding to the sun and annular gears are the same size. This can be done
by engaging the planet gears of two identical and coaxial epicyclic gear trains
to form a spur gear differential. Another approach is to use bevel gears for
the sun and annular gears and a bevel gear as the planet, which is known as a
bevel gear differential
Question
No. 34
What is pan hard rod or track bar?
Answer: A pan hard
rod is a bar or tube running from one side of the axle to the frame on the
other side of the vehicle. It helps the leaf spring in keeping the axle
centered under the body during turning a corner.
Question
No. 35
What is DTSI? Why this technology is used
in motor bikes?
Answer: DTSI stands
for Digital Twin Spark Ignition. This is used to get better combustion in the
combustion chamber. In this technique double spark plugs are used to obtain
better combustion of fuel in cylinder head. Through this technique fuel is
ignited properly. Moreover it provides better efficiency and it is economical
in fuel consumption.
Question
No. 36
What is the reason for emitting the white
exhaust smoke during start of the vehicle? How will you prevent this?
Answer: The main
cause of white smoke is water or anti-freeze entering the cylinder, so the
engine starts to burn it with the fuel. That white smoke is nothing but
steam.
Prevention measures: There are special gaskets i.e. head gaskets and primary gaskets that prevent the anti-freeze from entering into the cylinder area. This anti-freeze will produce a white steam which will accumulate at the tailpipe area.
Prevention measures: There are special gaskets i.e. head gaskets and primary gaskets that prevent the anti-freeze from entering into the cylinder area. This anti-freeze will produce a white steam which will accumulate at the tailpipe area.
Question
No. 37
What are three methods of heat transfer?
Answer: Three
methods of heat transfer are conduction, convection and radiation.
- Conduction: The transfer of energy by collisions between the atoms and molecules in a material.
- Convection: Transfers heat when particles move between objects or areas that differ in temperature.
- Radiation: The transfer of energy by waves.
Question
No. 38
What is BHP? How can you measure BHP?
Answer: BHP is
‘Brake Horsepower’. It reflects the powerfulness of the brakes of the vehicles.
BHP stands for how much power will be required to make the engine stop working
i.e. to stop the rotation of the engine.
BHP = 2 times pi times torque times revolutions; all this divided by 550.
π (Pi) is 3.1416 and torque is in pounds-feet, and revolutions are revs per second
BHP = 2 times pi times torque times revolutions; all this divided by 550.
π (Pi) is 3.1416 and torque is in pounds-feet, and revolutions are revs per second
Question
No. 39
During the drive torque, what will be the
weight shift?
Answer: In case of
cars the torque is applied to the rear wheels, thus limiting accelerator due to
front wheel drive due to weight transfer. This drive is bolted to the chassis
of the car. Modern manufacturers therefore design rear wheel drive to have
similar handling to front wheel drive wherever possible via suspension tuning.
Question
No. 40
Explain the reason that why big tyres are
used in rear of vehicles.
Answer: Large tyres
provide larger surface area touching the ground, thus providing the more
pulling power. Basically tractors have larger rear tyres because tractors don’t
have to operate at higher speeds, thus getting the same ground speed with
larger tyres. Moreover gear ratios don’t have to be as high as b/c of the
tyres.
Question
No. 41
When we
start a vehicle, exhaust smoke appears white. Why?
Answer: When you
start, the mixture is rich, and the exhaust will be cold, so any unburned
hydrocarbons and water vapor will condense out into a cloudy mist and appear
white.
Once the engine is warmed up, the exhaust system gets hot enough that the vapor is invisible.
Once the engine is warmed up, the exhaust system gets hot enough that the vapor is invisible.
Question
No. 42
What is an injector pressure in heavy
vehicles? Why it is used?
Answer: Injector
pressure i s the pressure at which the fuel can be injected into the vehicle.
In heavy vehicles, injector pressure is 220 kg/cm square. It is used to set up
the standard fuel injection in the vehicles. With the help of injector pressure
we can calculate the amount of fuel needed, through the following formula:
Est. Horsepower × B.S.F.C / No. of injectors × duty cycle = lb/hr per injector
cc = lb/hr × 10.5
Est. Horsepower × B.S.F.C / No. of injectors × duty cycle = lb/hr per injector
cc = lb/hr × 10.5
Question
No. 43
What is the size of the recommended
compressor CFM? Where it can be used?
Answer: It is
generally used in spray painting of very small areas. It can be used where
painting with brush is very difficult. Thus to improve the rate of painting the
spray painting is used as this method is very fast and efficient. Usually
reciprocating compressors are used but size depends on requirements.
Question
No. 44
What is a pressure cap in the radiator?
Answer: It is a seal
in the radiator that maintains the selected pressure in the cooling system when
the engine is hot.
Question
No. 45
How to
generate power from differential gear?
Answer: Differential
Gear comes under the category of Power transmitting mechanisms called Gears.
Gears can't generate power; they can only transmit the power from one source to
the receiver.
A Differential
Gear has three jobs.
- It directs engine power to the wheels. It's the connecting link between the drive shaft and the wheel axles.
- It acts as the final gear reduction in the vehicle, slowing the rotational speed of the transmission before it hits the wheels.
- The differential also transmits the power to the wheels while allowing them to rotate at different speeds.
Question
No. 46
How to
calculate bearing number to diameter of the inner and outer?
Answer: Divide the
shaft diameter size by 5, it will give last two digit of the bearing no. and
according to type of load we have to choose the type of bearing and that will
give prior no. of the bearing.
Question
No. 47
Define fit?
Answer: Fit
is defined as the degree of tightness and looseness between two meeting parts.
Question
No. 48
What is transverse weight shift due to
drive torque?
Answer: It
is weight of drive torque which is bolted to chassis of the car.
Question
No. 49
Why tractor rear wheel is big then front
wheel?
Answer: For
maximum torque provide
Question
No. 50
Does the
design & fittings vary on the type of the vehicle engine? Why they use
petrol for engines only & vice versa?
Answer: No, the type of fitting & design does not
vary for automotive segment. It’s the same. However, it’s different in
case of aerospace & other sector.
In the fittings, usually of hole/shaft one of
those is made at the basic size so that it can accommodate the other one.