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DEPARTMENT OF MECHANICAL ENGINEERING
Two Marks With Answers (2017 Regulation)
Subject Code : OAT551 (Open Elective)
Subject Name : Automotive System
Year/Semester : III/V
Author - Biography
Prof.S.Sathishkumar.BE (Mechanical Engineering)., ME (Engineering Design)., MBA (Operations
Management).,MISTE
Assistant Professor, Department of Mechanical Engineering
Vel Tech (Owned By RS Trust) Engineering College, Avadi, Chennai-62
Website : www.kssathishkumar.blogspot.com
Email : [email protected]&[email protected]
Mobile : 9994274071, 9597178818
Face Book : K.s. Sathishkumar
Twitter : K.s. Sathishkumar
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SYLLABUS
OAT 551-AUTOMOTIVESYSTEM
OBJECTIVES:
Tounderstandtheconstructionandworkingprincipleofvariouspartsofanautomobile. To have the practice for assembling and dismantling of engine parts and transmission
system
UNIT I AUTOMOTIVE ENGINEAUXILIARYSYSTEMS 9
Automotive engines‐ External combustion engines –Internal combustion engines ‐classification of engines‐ SI Engines‐ CI Engines‐ two stroke engines ‐four stroke engines‐ construction
and working principles ‐ IC engine components‐ functions and materials‐valve timing –port timing
diagram‐ Injection system ‐Unit injector system‐ Rotary distributor type-Electronically controlled injection
system for SI engines‐CI engines‐Ignition system ‐ Electronic ignition system ‐Transistorized ignition
system, capacitive discharge ignitionsystem.
UNIT II VEHICLE FRAMES ANDSTEERINGSYSTEM 9
Vehicle construction and different Chassis layouts –classifications of chassis‐ types of framesframeless
chassis construction –articulated vehicles‐ vehicle body ‐ Vehicle aerodynamics‐various resistances and its
effects ‐ steering system –conventional – sophisticated vehicle‐ and types of steering gear box‐Power
Steering‐ Steering geometry‐condition for true rolling motion‐Ackermann‟s‐ Devi‟s steering system ‐ types of stub axle – Types of rear axles.
UNIT III TRANSMISSIONSYSTEM 9
Clutch‐types and construction, gear boxes‐ manual and automatic, gear shift mechanisms, Over drive,
transfer box, fluid flywheel, torque converter, propeller shaft, slip joints, universal joints –‐ Hotchkiss
Drive and Torque Tube Drive‐ rear axle‐ Differential‐wheels and tyres.
UNIT IV SUSPENSION ANDBRAKESSYSTEM 9
Suspension Systems‐ conventional Suspension Systems ‐independent Suspension Systems –leaf spring –
coil spring –taper‐lite ‐ eligo,s spring Types of brakes ‐Pneumatic and Hydraulic Braking Systems,
Antilock Braking System (ABS), electronic brake force distribution (EBD) and Traction Control. Derive
the equation of Forces acting while applying a brakes on plain surface ‐ inclined road‐gradient.
UNIT V ALTERNATIVE ENERGY SOURCES 9
Use of Natural Gas, Liquefied Petroleum Gas, Bio‐diesel, Bio‐ethanol, Gasohol and Hydrogen in
Automobiles‐ Engine modifications required –Performance, Combustion and Emission Characteristics of
SI and CI engines with these alternate fuels ‐ Electric and Hybrid Vehicles, Fuel Cell. Turbo chargers ‐Engine emission control by three way catalytic converter system.
Note: Practical Training in dismantling and assembling of Engine parts and Transmission
Systems should be given to the students.
TOTAL: 45 PERIODS
OUTCOMES:
Upon completion of this course, the students will be able to identify the different components in
automobile engineering.
Have clear understanding on different auxiliary and transmission systems usual.
TEXT BOOKS:
1. GanesanV.“InternalCombustionEngines”,ThirdEdition,TataMcGraw‐Hill,2007.
2. Jain K.K. and Asthana .R.B, “Automobile Engineering” Tata McGraw Hill Publishers, New
Delhi,2002.&Kirpal Singh, “Automobile Engineering”, Vol 1 & 2,7thStandard Publishers-, New
Delhi,1997
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GRAPHICAL REPRESENTATION OF AUTOMOTIVE SYSTEM
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UNIT-1
AUTOMOTIVE ENGINE AUXILIARY SYSTEMS
PART-A – (Two Marks)
INTRODUCTION OF AUTOMOTIVE ENGINE
Heat engine defined as ait is a device which transforms the chemical energy of a fuel into thermal energy and uses
this energy to produce mechanical work. It is classified into two types-
(a) External combustion engine
(b) Internal combustion engine
1. Define: Automotive Engine
Automotive engineering is a branch of engineering which deals with everything about automobiles and
practices to propel them. Automobile is a vehicle driven by an internal combustion engine and it is used
for transportation of passengers and goods on the ground. Automobile can also be defined as a vehicle
which can move by conversion of chemical energy to Mechanical Energy
Examples: Car, jeep, bus, truck, scooter, etc.
2. Mention the Classification of Automotive Engine
Automotive Engines are generally classified according to following different categories: Internal
combustion (IC) and External Combustion (EC)
Type of fuel: Petrol, Diesel, Gas, Bio / Alternative Fuels.
Number of strokes – Two stroke Petrol, Two-Stroke Diesel, Four Stroke Petrol / Four Stroke Diesel
3. Write about External Combustion Engine
External Combustion Engine also called as heat engine that derives its heat from fuel consumed outside
the cylinder
Examples: Steam engine
4. Define Internal Combustion Engine
Internal combustion engine is defined as the combustion of air and fuels take place inside the cylinder and
are used as the direct motive force.
5. Mention the Classification of Internal Combustion Engine
1.According to the method of igniting the fuel
(a) Spark ignition engine,
(b) Compression ignition engine and
(c) Hot spot ignition engine
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2. According to the type of fuel used
(a) Petrol engine
(b) Diesel engine
(c) Gas engine (CNG, LPG)
(d) Alcohol engine (ethanol, methanol etc)
3. According to the number of strokes per cycle
(a) Four stroke
(b) Two stroke engine
4. According to the basic engine design
(a) Reciprocating engine (Use of cylinder piston arrangement)
(b) Rotary engine (Use of turbine)
5. According to the working cycle
(a) Otto cycle (constant volume cycle) engine
(b) Diesel cycle (constant pressure cycle) engine
(c) Dual combustion cycle (semi diesel cycle) engine
6. Write the Differentiation between the External and Internal Combustion Engine
S/No External Combustion Engine Internal Combustion Engine
1 Combustion of air-fuel is outside the
engine cylinder (in a boiler)
Combustion of air-fuel is inside the engine
cylinder (in a boiler)
2 It can use cheaper fuels including solid
fuels
High grade fuels are used with proper
filtration
3 Higher ratio of weight and bulk to output
due to presence of auxiliary apparatus like
boiler and condenser. Hence it is heavy
and cumbersome
It is light and compact due to lower ratio of
weight and bulk to output
4 The engines are running smoothly and
silently due to outside combustion
Very noisy operated engine
5 Lower efficiency about 15-20% . Higher efficiency about 35-40%
6. Define Spark Ignition Engine
A spark-ignition engine (SI engine) is an internal combustion engine, it is also called petrol engine, where
the combustion process of the air-fuel mixture is ignited by a spark from a spark plug.
7. State Compression Ignition Engine
Compression-ignition engines also called as diesel engines, where the heat generated from compression
together with the injection of fuel is enough to initiate the combustion process, without needing any
external spark.
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8. Write the different between Two Stroke and Four Stroke Engine
S/NO TWO STROKE ENGINE FOUR STROKE ENGINE
1 It has one revolution of the
crankshaft during one power stroke
It has two revolutions of the crankshaft during
one power stroke
2 It generates high torque It generates less torque
3 Its uses ports for fuel’s outlet and
inlet It uses valves for outlet and inlet of a fuel
4 It generates more smoke and shows
less efficiency
It generates less smoke and shows more
efficiency
5 Engines are cheaper and are simple
for manufacturing
Engines are expensive due to lubrication and
valves and are tough to manufacture
9. Enlist the IC Engine Components
Cylinder block
Cylinder Head
Piston
Piston Pin or Gudgeon pin
Connecting Rod
Crank Shaft
Cam Shaft
11. What are the two types of cylinder liners?
1. Dry liners 2.Wet liners
12. What are the functions of piston rings?
To provide a gas tight seal between the piston and cylinder liner to prevent the escape of gases from top
side of the piston to the underside.
13. What are the two types of piston rings?
Compression rings
Oil rings
14. What is clearance volume? And what are its effects?
The volume above the piston, when it reaches TDC is known as clearance volume. The clearance volume
is inversely proportional to the compression ratio.
15. What is the function of piston, connecting rod, crank shaft and cylinder head?
Piston – The piston assembly transfers the force from the power stroke to the crankshaft
Connecting rod – converts reciprocating motion of piston into rotary motion of crankshaft
Cylinder head – it acts as a top cover to the cylinder block. The valves are placed in the cylinder
head in an overhead valve engine.
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16. What are the functions of Piston rings?
Prevention of leakage of gas into the crankcase
Prevention of lubricating oil film.
Easy transmission of heat from piston to cylinder wall.
Balancing of side thrust of the piston.
17. Define manifolds?
The term manifold is applied to the external pipes or castings containing gas passages that connect
the carburetor and the pipes to the inlet and outlet ports of the engine. In order to maintain
maximum velocity of the gases and to ensure the best possible breathing, it is obviously desirable that
the passages should offer minimum resistance to flow.
18. What are the qualities of a good liner?
Strength to resist stresses due to pressure.
Hard to resist wear.
Capable of taking a good bearing surface.
Strength to resist stresses due to heat flow through the liner.
19. What are the forces acting on crank shaft?
i) Centrifugal force ii) Inertia force iii) Twisting and shear forces.
20. Define common rail injection system.
A common rail which is maintaining high fuel pressure is connected to individual fuel injectors of a multi
cylinder engine.
21. What is unit injection system?
It is an integrated direct fuel injection system for diesel engines, combining the injector nozzle and the
injection pump in a single component
22. What is a rotary distributor?
The rotary distributor has a rotating element, which releases a high intensity spark to the individual spark
plugs according to the engine firing order.
23. What is an Electronic ignition system?
The ignition system, in which the mechanical contact points are replaced by electronic triggering and
switching devices, is known as electronic ignition system
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24. State the merits and demerits of Mono point and Multi point fuel injection system?
No. Mono Point Injection Multi Point Injection
1 Single injector is sufficient Separate fuel injector for individual cylinders
2 Low cost High cost 3 Low injection pressure Comparatively higher injection pressure
4 Slightly higher SFC and emissions than Low SFC and engine emissions MPFI
25. What is the function of an ignition system in I.C Engine?
The function of an ignition system is to ignite the air-fuel mixture at the end of the compression stroke.
26. State the requirements of ignition system? And state its types
It should consume minimum of power and produce high intensity spark across spark plug
electrodes
It should have a sufficient spark duration which is sufficient to establish burning of air- fuel mixture
under all operating conditions
It should provide sufficient ignition energy over the entire speed range of theengine
Good performance at high speed
Longer life of contact breaker points and sparkplug
Adjustment of spark with speed & load
27. List out the types of Ignition System
1. Battery ignition 2. Magneto ignition 3.Electronic ignition
28. Write the Different between battery coil ignition and magneto ignition system
S/No Battery Ignition Magneto Ignition
1 Battery supplies current in primary circuit Magneto produces the required current for primary circuit
2 A good spark is available at low speed also Quality of spark is poor in slow speed
3 Occupies more space Very much compact
4 Recharging is a must in case battery gets discharged
No such arrangement required
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UNIT II
VEHICLE FRAMES AND STEERING SYSTEM
1. Define Chassis
A complete vehicle without a body structure is known as Chassis. It comprises of basic structure, power
unit, transmission system, controls and auxiliaries.
2. What are the functions of a frame?
To support the chassis components and the body.
To withstand static and dynamic loads without undue deflection or distortion.
To carry the load of the passengers or goods carried in the body.
3. List out the various materials used in the construction of frame.
Low Carbon Steel - 0.18 or 0.20 % carbon content
High Carbon Steel - 0.25 % carbon content
Alloy Steel – With alloying elements like Ni & Cr.
4. Types of Chassis Frames?
There are three types of frames
Conventional frame Integral frame
Semi-integral frame
5. List out the main components of the Chassis
Frame
Engine or Power plant
Clutch
Gear Box
U Joint
Propeller Shaft
Differential
6. Mention various loads acting on the vehicle frame
Short duration Load - While crossing a broken patch.
Momentary duration Load - While taking a curve.
Impact Loads - Due to the collision of the vehicle. Inertia Load - While applying brakes. Static Loads - Loads due to chassis parts.
Over Loads - Beyond Design capacity. 7. Write the Requirements of Bodies for Various Types of Vehicles The body of the most vehicles should fulfill the following requirements: The body should be light. It should have minimum number of components.
It should provide sufficient space for passengers and luggage. It should withstand vibrations while in motion.
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It should offer minimum resistance to air 8. Name the different kind of resistances to vehicle motion.
Air resistance
Rolling resistance
Gradient resistance
9. What loads are coming to axle?
Vertical bending load due to vehicle weight
Driving torque
Braking torque
Side thrust
10. What are the advantages of frameless construction over the conventional framed
Construction?
Reduced weight and consequent saving in fuel consumption.
Lower manufacturing cost
During collision the body crumbles, thereby absorbing the shock due to impact and thus
providing safety to the passengers.
Compared to framed construction lower body position may be obtained, thus resulting in
increased stability of the automobile
11. What is the different type of steering gears?
a) Worm and wheel steering gear
b) Cam and double roller steering gear
c) Worm and nut steering gear
d) Reticulating ball type steering gear
e) Rack and pinion steering gear
12. Define steering ratio.
It is the ratio of the angle turned by the steering wheel to the corresponding turning angles of the stub
axle. The steering ratio generally used with the present day steering gears vary from about 12:1 for cars
to about 35:1for heavy vehicles.
13. What is power steering?
Large amount of torque is required to be applied by the driver for steering medium and heavy vehicles.
The power steering system provides automatic hydraulic assistance to the turning effort applied to the
manual steering system.
14. What is the advantage of electronic power steering over hydraulic power steering?
No problem of leakage of fluid.
Energy being consumed only while steering.
Steering assistance available even when the engine is not running.
While steering manually lesser force is required compared to a hydraulic system since there is no
fluid to be forced through valves.
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15. Write about reversible steering & irreversible steering
Reversible steering
When deflection of the steered wheels due to road surface is transmitted through the
steering linkage and steering gear box to the steering wheel the system is said to be
reversible.
Irreversible steering
When the steered wheels do not transfer any deflection to the steering wheel, the steering
system is said to be irreversible.
16. What is over steering & under steering?
Over steering
When the rear slip angle is greater than the front slip angle, the vehicle tends to move
away from the direction of the side force. This is known as over steer and is advantageous
when the vehicle is moving on roads having many bends and curves.
Under steering
When the front slip angle is greater than the rear, the vehicle tends to steer in the direction
of side force. This is called under steer. This provides greater driving stability especially
when there is a side wind.
17. State Ackermann principle of steering.
The basic principle of Ackermann steering system to obtain true rolling. The Ackermann steering gear
mechanism consists of a cross link KL connected to the short axes AC and BD of the two front wheels
through the short arms AK and BL. Forming bell crank levers CAK and DBL respectively. When the
vehicle is running straight the cross link KL is parallel to AB. The short arm AK and BL both make
angle α to the horizontal axis of chassis.
For correct steering, cot Φ – cot θ = b / l
18. Define centre point steering?
If the imaginary king pin axis and the centre line of the wheel meet at the road surface this condition is
known as ‘Centre point steering’. If this condition is allowed in the front wheels the bending stress and
the splaying couple are greatly reduced.
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UNITIII
TRANSMISSION SYSTEM
1. What is the necessity of transmission system in automobile?
a) Variation of resistance to the vehicle motion at various speeds.
b) Variation of tractive effort of the vehicle motion at various speeds.
2. What is the function of a clutch?
A mechanism which enables the rotary motion of one shaft to be transmitted, when desired, to a second
shaft, the axis of which is coincident with that of the first.
3.What is “clutch free pedal play”?
When the clutch pedal is pressed, the trust bearing is not pressed immediately. Rather a part of the pedal
movement is purposely kept idle. This is done to avoid a rapid wear of the thrust bearing and the clutch
plates and is called clutch free pedal play.
4. Why are cone clutches better than disc clutches?
Since the cone discs are having large frictional areas and welding action, they can transmit a larger torque
than disc clutches with the same outside diameter and actuating force and hence cone clutches are
preferred to disc clutches .But usually cone clutches are mainly used in low peripherals speed
applications.
5. Define slip in the clutch. Write down the causes for it.
A large amount of heat is generated due to which clutch facings wear out rapidly and even burn out. This
is called as slip in the clutch. This may be caused by the following reasons.
Incorrect linkage adjustment
Weak or broken clutch springs.
Worn out facings
6. What are the main components in friction clutch?
Clutch plate
Clutch facing
Pressure plate
Springs
Bearing
7. What do you mean by fluid flywheel?
It is an alternative to clutch, uses fluid for transmitting the torque. It is also called hydraulic coupling.
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8. What is the function of a synchronizer in a gearbox?
It is used for avoids the double declutching. It fitted only on the high gears and on the low and
reverse gears ordinary dog clutches are only provided. This is done to reduce the cost.
9. List out some automatic transmission device.
Epicyclical gear box
Multi plate clutches
Torque convertor
10. Difference between torque convertor and fluid flywheel
Fluid flywheel
The fluid flywheel transmits the same torque given to it b y the engine shaft.
Stator is not there.
Efficiency is low.
Torque convertor
The torque convertor increases the torque in a ratio of about 2:1 to3:1.
Stator is there.
Efficiency is high.
11. What is the function of stator in a torque convertor?
Stator is used for avoid the dragging action on the impeller.
12. Define over drives. What are its advantages?
Overdrive is a device to step up the gear ratio in the car. It is fitted in between transmission
and the propeller shaft.
13. Define propeller shaft and list out various parts of propeller shaft.
This is the shaft which transmits the drive from the transmission to the bevel pinion or worm
of final drive in front engine rear drive vehicles. It is also called as drive shaft. It consists
mainly of three parts
Shaft
One or Two universal joints
Slip joint
14. What is the function of universal joint?
It is a special type of joint between two shafts whose axes are inclined to each
other. Most common example is the Hook’s joint.
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15. List out various steps involved in the overhaul of propeller shaft
Removal of the shaft from the chassis
Dismantling
Inspection and service
Reassembling
Refitting
16. List out three types of final drives
Straight bevel gears
Spiral bevel gears
Hypoid gears
17. What is the need for a differential mechanism in an automobile?
When the vehicle is taking a turn, the outer wheels will have to travel greater distance as compared to
the inner wheels in the same time. If therefore, the vehicle has a solid rear axle only and no other device;
there will be tendency for the wheels to skid. Hence the wheel skidding is to be avoided, some
mechanism must be incorporated in the rear axle, which should reduce the speed of the inner wheels
and increase the speed of the outer wheels when taking turn ; it should at the same time keep the speeds
of all the wheels same when going straight ahead.
18. List out various forces acting on rear axle.
Weight of the body
Driving thrust
Torque reaction
Side thrust
19. List out two type of rear axle drive & rear axle casting
Hotchkiss drive
Torque tube drive
Split type
Banjo or separate carrier type
Salisbury or integral carrier type.
20. What are the functions of brake?
i) To stop the vehicle,
ii) To control speed, when and where required quickly and efficiently,
iii) To control the vehicle while descending along a slope,
iv) To keep the vehicle in the required place after bringing it to rest
even when the operator is not present.
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21.What are the types of brakes?
1. Feed brake 2.Hand brake 3.Mechanical brake 4.Hydraulic brake
5.Vacuum brake 6.Electrical brake 7.Air brake 8.Disc brake.
22. What are the braking requirements?
It should develop maximum possible retarding force irrespective of road conditions
and quality.
The response time should be as minimum as possible.
Must be reliable.
Should be of minimum weight.
Noise and vibration are to be minimum.
23. What are brake drums?
Brake drums are made of steel or alloy of chrome nickel. The walls of the drums are very thin
and made of centrifugal castings. The brake drum assembly is mounted on the wheel bolts between
the hub and the wheel, so as to revolve with the wheel. The drum surrounds the brake shoes. The drum
diameter ranges from 200 to 375 mm.
24. What is a master cylinder?
The master cylinder is the heart of the hydraulic brake system. The master cylinder is the fluid
reservoir for the brake and is operated by the brake pedal.
25. What is tandem master cylinder?
Tandem master cylinder refers to the master cylinder arrangement with two separate cylinders
and reservoir in the same master cylinder assembly. One cylinder to operate the front brakes and the
other to operate the rear brakes. So because of this arrangement even if any one of the cylinders goes
out of order, the other cylinder functions for the operation of the brake
26. What are the merits of air brakes?
More effective: heavy effort at brakes.
Employs only air as working medium which is easily available.
Better control.
Reduced stopping distance.
27. What are disc brakes?
The motor vehicles are now being fitted with disc brakes. It is normally of a caliper type,
consisting of a rotating disc and two friction pads on either side. The disc is made of high grade grey
cast iron. The friction pads are made up of asbestos fibre. The chief advantage of the disc brake is their
resistance to fading.
28. What are the merits of disc type brakes?
Better stability because of uniform pressure distribution over the pads.
Less bearing load on the application of the brake.
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Higher temperature does not affect the disc pads.
Simple design of brake adjuster.
Less weight
Repair and maintenance are easy.
Resistance to fading.
29. What are power brakes?
Normally for operation of brakes some physical effort is applied on the brake pedal. If instead
of physical effort some other external source of power is applied then it is known as power brake. The
external sources may be air pressure, engine vacuum or electrical energy from battery.
30. What are the advantages of power brakes?
Reduces driver’s effort.
Higher braking efficiency.
More rapid in action.
Lesser time lag.
Used in trailers and tractors.
Flexible hose connection.
31. What are the various brake troubles?
Sl.No.
Troubles
Causes
1. Pedal can be moved to strike floor
board without producing braking
action.
1. Normal wear of linings
2. Defective master cylinder
3. Air in system
2. One wheel drag 1. Brakes too tight.
2. Clogged liner.
3. Brake fade 1. Too hot brake drum
2. Glazed lining.
4. Spongy pedal 1. Air in line
2. Poor shoe adjustment.
32. What are the functions of the gear box?
To exchange engine power for greater torque and provide mechanical advantage to drive
the vehicle under different operating conditions.
To provide reverse motion.
To provide neutral position and disallow power flow to the rest of the transmission.
33. What is the necessity of gear box?
To regulate the torque by selecting the appropriate speed range.
To regulate vehicle speed at which maximum torque is available.
To balance the tractive effort with the sum of the various forces tending to
oppose the motion.
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34. Define tractive effort.
Tractive effort is the driving force which acts at the rear wheel to propel the vehicle. To
obtain uniform speed, the total tractive resistance should be balanced by the tractive effort. Tractive
effort is produced at the point of contact of the wheel on the road.
T = Total torque at the wheel / Wheel radius
= n x m x r x T
where,
n = gear box ratio m =
final drive ratio
r = radius of the wheel T =
engine torque.
35.What are the type of gear boxes?
i) Selective type ii) Progressive type
36.What is an epicycle gear box?
This is also known as planetary gear train. One shaft is called sun gear shaft and the other
shaft is called planet carrier shaft. The epicyclical gear box uses no sliding dogs or gears to engage,
but different gear speeds are obtained by merely tightening brake bends on the gear drums, which
simplify gear changing. A three speed gear box provides 3 speed gears: I, II, and top gear. A four
speed gear box provides 4 speed gears: I, II, III and top gear. A five speed gear box provides 5 speed
gears: I, II, III, IV and top gear.
37.What is gear shifting?
The gears are shifted by means of a gear shift lever. In manually operated selective
transmissions, the gear shift lever is located either on steering column or on the floor board. To shift
any gear the clutch pedal is depressed to disconnect momentarily the engine from the transmission.
Then the gear shift lever is moved first to demesh the previous gear and then to mesh the desired
gear. The directions of the first, second, third, neutral and reverse gears are marked on the knob of
the gear shift lever.
38. What is a transfer case?
The transfer case is essentially a two speed transmission located at the rear of the standard
transmission which provides a low and direct gear. It also provides a means of connecting the power
to the front axle. The shifting mechanism is located on the transfer case.
39. How does a tyre being specified?
i) Width ii) Speed rating and diameter iii)Ply rating.
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40. What are the causes for rapid wear of a tyre?
Rapid wear: Operating condition like rough surface, high speed.
Remedy: Maintain correct speed, correct pressure.
41. What is tubeless tyre?
Tubeless tyre does not enclose the tube. The air under pressure is filled in the tyre itself. A non-return
valve is fitted to the rim through which the air is forced inside the tyre. Any hole in tubeless tyre can
be repaired simply by rubber plugging.
42. What are the causes of tyre wear?
i)Incorrect inflation ii)Incorrect caster, camber or toe-in, iii) Over loading , iv) Wrong loading,
v)Misalignment, vi)Unequal tyres vii)Careless driving viii)Worn kingpins.
UNIT-IV
SUSPENSION AND BRAKES SYSTEM
1. What is the need of suspension system?
i) To safeguard the passengers and goods against road shocks.
ii) To pressure the stability of the vehicles while in motion.
iii) To maintain proper steering geometry.
iv) To bear the torque and braking reaction.
2. What is independent front suspension?
The term independent suspension system means any arrangement that connects the road wheels
to the frame; in which the rise or fall of one wheel has no direct effect on the other wheels.
3. What are the advantages of independent front suspension?
More space for engine accommodation.
It enables front springs to be arranged for enough apart to promote under steer conditions,
which is preferable to over steer.
It may provide softer suspension.
4. What is sprung and unsprung weight?
Sprung weight is the weight of all the parts supported by the springs including the weight
of springs.
Unsprung weight is the weight of all parts between the springs and the rod and a portion of
the spring weight itself.
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5. What are the functions of a spring?
To provide cushioning effect for the passengers.
To absorb and store energy.
To prevent or reduce the transmission of road shocks as far as possible.
6. What are spring shackles?
Spring shackles provide the link by means of which the chassis frame is connected to the
leaf spring. The shackles help the spring to spring in and out during flattering and rebounding. This
is provided for lubricating purposes.
7. What is a torsion bar?
A torsion bar is a steel bar which functions by twisting and absorbing shear stress only. This is
generally used in front independent suspension. The energy absorbed per unit volume by torsion
bar is 4 times that of a leaf spring and 3 times that of a coil spring.
8. What are the advantages of torsion bar?
i) Light ii) Occupies less space iii) Stiff iv) Easy to assemble & v) Double acting.
9. What is a shock absorber?
Shock absorber controls the spring action during compression and rebound and prevents
bouncing. To control vibration shock absorber is used.
10. What are the types of shock absorber?
i) Mechanical shock absorber
ii) Hydraulic shock absorber
11. What is a fluid coupling?
This is a liquid coupling used to transmit the engine turning force to a clutch. It is located
between the crankshaft and the clutch. Air is the fluid used as a medium of power transmission.
12. Compare fluid coupling and torque converter.
Sl.No. Fluid coupling Torque convertor
1. Contains only two members impeller And turbine.
Three members impeller, turbine and a stator.
2. Simply a torque transmission unit. Torque multiplication unit 3:1 to 4:1
3. Efficient at high speed. Inefficient at high speeds.
4. Serves as an automatic clutch. Serves as an automatic clutch as well
as torque multiplier.
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13. What are the functions of brake?
iii) To stop the vehicle,
iv) To control speed, when and where required quickly and efficiently,
v) To control the vehicle while descending along a slope,
vi) To keep the vehicle in the required place after bringing it to rest
even when the operator is not present.
14. What are the types of brakes?
i)Feed brake ii) Hand brake iii) Mechanical brake iv) Hydraulic
brake v)Vacuum brake vi) Electrical brake vii) Air brake and viii)Disc brake.
15. What are the braking requirements?
It should develop maximum possible retarding force irrespective of road conditions and
quality.
The response time should be as minimum as possible.
Must be reliable.
Should be of minimum weight.
Noise and vibration are to be minimum.
16. What are brake drums?
Brake drums are made of steel or alloy of chrome nickel. The walls of the drums are very thin and
made of centrifugal castings. The brake drum assembly is mounted on the wheel bolts between the
hub and the wheel, so as to revolve with the wheel. The drum surrounds the brake shoes. The drum
diameter ranges from 200 to 375 mm.
17. What is a master cylinder?
The master cylinder is the heart of the hydraulic brake system. The master cylinder is the
fluid reservoir for the brake and is operated by the brake pedal.
18. What is tandem master cylinder?
Tandem master cylinder refers to the master cylinder arrangement with two separate cylinders and
reservoir in the same master cylinder assembly. One cylinder to operate the front brakes and the
other to operate the rear brakes. So, because of this arrangement even if any one of the cylinders
goes out of order, the other cylinder functions for the operation of the brake.
19. What are the merits of air brakes?
i) More effective: heavy effort at brakes.
ii) Employs only air as working medium which is easily available.
iii) Better control.
iv) Reduced stopping distance.
20. Define disc brakes
The motor vehicles are now being fitted with disc brakes. It is normally of a caliper type,
consisting of a rotating disc and two friction pads on either side. The disc is made of high grade
grey cast iron. The friction pads are made up of asbestos fibre. The chief advantage of the disc
brake is their resistance to fading.
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21. Write the merits of disc type brakes?
Better stability because of uniform pressure distribution over the pads.
Less bearing load on the application of the brake.
Higher temperature does not affect the disc pads.
Simple design of brake adjuster.
Less weight
Repair and maintenance are easy.
Resistance to fading.
22. Define power brakes?
Normally for operation of brakes some physical effort is applied on the brake pedal. If
instead of physical effort some other external source of power is applied then it is known as
power brake. The external sources may be air pressure, engine vacuum or electrical energy from
battery.
23. Mention the advantages of power brakes?
Reduces driver’s effort.
Higher braking efficiency.
More rapid in action.
Lesser time lag.
Used in trailers and tractors.
Flexible hose connection.
24. What are the various brake troubles
Sl.No. Troubles Causes
1.
Pedal can be moved to strike floor
board without producing braking
action.
1. Normal wear of linings
2. Defective master cylinder
3. Air in system
2. One wheel drag 1. Brakes too tight.
2. Clogged liner.
3. Brake fade 1. Too hot brake drum
2. Glazed lining.
4. Spongy pedal 1. Air in line
2. Poor shoe adjustment.
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UNIT V
ALTERNATIVE ENERGY SOURCES
1. What are the general compositions for natural gas?
1. Methane: 85-90% 2. Ethane: 5-7% 3. Propane: 2 % 4/ Carbon dioxide: 3-5% 5. Others: 1%
2. What are the physical properties of natural gas?
1. Colourless 2.Odourless 3. Non-toxic 4. Lighter than air.
3. What is the need for CNG?
a. Rising urban pollution.
b. Rising global concern for environment.
c. Rising vehicle pollution.
4. What are the constraints in natural gas?
d. Gas availability.
e. Availability of CNG equipment.
f. Pipeline network infrastructure.
g. Competition from other fuels.
5. What are the different concepts used in the description of CNG system?
h. Mother-Daughter concept.
i. On-line station concept.
6. What are the advantages of using compressed natural gas over diesel?
j. Natural gas provides clean burning characteristics.
k. Natural gas does not saturate flammable materials.
l. The explosive limit of natural gas mixture is higher than air-diesel mixture.
7. What are the components of LPG pipe line
Vapourizer
Regulator
Safety valve
Mixer
Fuel line
8. What are the methods for using hydrogen into the cylinder?
a. by manifold connection.
b. by direct injection of hydrogen.
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c. by supplementation to gasoline.
9. What are components of an electric vehicle?
Motor.
Power pack.
Onboard charger.
Motor controller.
Energy management.
Regenerative braking.
10. What are the advantages of electric car?
Maintenance cost is low.
Vibration free operation
Lighter in weight.
11. Mention the classification of Hybrid vehicles?
Series Hybrid.
Parallel Hybrid.
12. What are the components of Hybrid cars?
Electric motor.
Generator.
Direct injection gasoline.
13. What is meant by a fuel cell? Mention Types
A fuel cell is a device that harnesses the energy produced during the electro chemical reaction between
hydrogen and oxygen. The products are water and electricity.
Types:
Alkaline fuel cell
Phosphoric acid fuel cell
Direct methanol fuel cell
Solid oxide fuel cell
Molten carbonate fuel cell
14. What is the need of fuel cell?
a) Depletion of conventional types of fuels leading to energy crisis.
b) Low emission required to make a car economic friendly.
c) To attain certain standards of emission control.
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15. List out fuel cell gases
a) Oxygen
b) Hydrogen
16. What are the advantages of fuel cell?
The fuel cell has low emission of pollutants.
The oxygen air bags are varying useful for the passenger.
The fuel cell prevents the depletion of the fossil fuels.
The CO2 exhaled by the passenger is also removed.
17. What are the requirements of hybrid vehicle?
a) Increased fuel efficiency
b) Reduced emissions
c) Increased acceleration capacity
d) Reduced noise emission
18. Write short notes on series hybrid vehicles
The engine runs a motor directly and also charges a battery. Thus the motor thus drives the vehicle
always. The motor can also be used for regenerating braking.
19. What are components of hybrid cars?
a) An electric motor
b) A generator
c) Direct injection gasoline engine.
20. List the advantages of hydrogen fuel used in automobiles.
It can be manufactured from water through electrolysis process
It does not contain carbon. Hence, CO and unburned HC emissions are not present. The flame
speed is highest. Hence it results in high thermal efficiency
It has wide ignition limits.
21. Define detonation and pre-ignition
The abnormal combustion occurring in IC engines is called as detonation. This results in sudden
rate of pressure rise, abnormal heat release, heavy vibrations of the engine and loud noise
operation.
The ignition of the air-fuel mixture before the introduction of the spark in the combustion
chamber is called as pre-ignition.
22. What are the disadvantages of using alcohol as an alternative fuel?
A larger quantity of fuel is required to produce a specified power output. For example, in an
automobile, more fuel is required for each mile driven.
Low boiling points and high vapor pressures of methyl and ethyl alcohol indicate that vapor
Lock could be a serious problem, particularly at high altitudes on warm summer days.
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23. List out the various forms of Natural Gas.
Natural Gas (NG)
Compressed Natural Gas (CNG)
Liquefied Natural Gas (LNG)
24. Write down the components of LPG equipment.
Converter
Mixer
Gas Injector
25. What are the properties of CNG?
Colorless
Odorless
Lighter than air
Non - toxic
26. What are the two types of LPG used for automotive-engine fuel?
Propane based LPG
Butane based LPG
************** Wish You Happy Learning ************
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