Steering geometry and types of steering gear box-Power Steering- Pneumatic and Hydraulic Braking Systems - Antilock Braking System (ABS)- Electronic brake force distribution (EBD) and Traction Control - Types of Front Axle- types of Suspension systems

1. KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY
(AUTONOMOUS)
NAMAKKAL- TRICHY MAIN ROAD, THOTTIAM, TRICHY
DEPARTMENT OF MECHANICAL ENGINEERING
20ME603PE - AUTOMOBILE ENGINEERING
SIXTH SEMESTER
PRESENTED BY
M.DINESHKUMAR,
ASSISTANT PROFESSOR,
DEPARTMENT OF MECHANICAL ENGINEERING,
KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY.

2. UNIT-IV
STEERING, BRAKES AND
SUSPENSION SYSTEMS

3. • Function of steering system:
• It provides wheels swinging to the left of right
• It provides vehicle turning as per the will of the
driver
• It provides the directional stability
• It helps to control wear and tear of tyres
• It helps in achieving the self rightening effect
• It converts the rotary movement of the steering
wheel into an angular turn of front wheels
• It multiples the effort of the driver by leverage to
make wheels easy to turn
• It absorbs a major part of road shocks in such a way
from being transmitted to hands of the driver.

4. LAYOUT OF STEERING SYSTEM

5. • Steering wheel: control wheel to steer a vehicle
by the driver. It contains traffic indicator switch,
light switch, wiper switch.
• Steering linkage: Steering wheel are turned by
the steering linkage. It consists of pitman arm,
ball joints, drag link, steering arm, spindle, tie
rod kingpin assembly.
• Pitman arm: In which converts the output
torque from the steering gear into force to the
drag link.
• Drag link: It is connected between pitman arm
and steering arm.

6. • Ball joints: these joints are connected at both
ends of the drag link and tie rod. It performs the
angular displacement, rotational movement of
the drag link and tie rod produced by the front
wheel rotation.
• Tie rod: It is tubular member. Both the left and
right tie rod arms are connected by this tie rod.
The force is transmitted between these two
components.
• Steering gear: The pitman arm is splined to the
steering gear box rocker arm at one end and the
other end is connected to the drag link by a ball
joint.

7. STEERING GEOMETRY
• Castor
• Camber
• Kingpin inclination
• Toe-in
• Toe-out

8. • Requirements of the steering system:
• It multiples the turning efforts applied on the
steering wheel by the driver
• The shocks of the road surface absorbed by wheel
should not be transmitted to the driver’s hand.
• When ever driver releases the steering wheel
after completing the turn, the wheel should
achieve a straight ahead position immediately.
• It must keep the wheel at all time in rolling
motion without rubbing on the road.
• It must be light and stable
• It must easily be operated with less maintenance.

9. • Function of the steering system:
• It provides wheels swinging to the left or right
• It provided vehicle turning as per the will of the
driver
• It provides the directional stability
• It helps to control wear and tear of tyres
• It helps in achieving the self rightening effect
• It converts the rotary movement of the steering
wheel into an angular turn of front wheels.
• It absorbs a major part of road shocks in such a
way from being transmitted to hands of the
driver.

10. CAMBER
The camber should not exceed to 2 degree

11. • Effects of wheel camber:
• Bending stresses in the kingpin and stub axle are
reduced.
• Steering effort is drastically reduced.
• Shock loads are not permitted to transmit to the
steering wheel at high speeds
• It imparts the directional stability.

12. CASTER
Castor angle ranges from 2 to 7 degree in modern vehicles

13. KINGPIN INCLINATION
• The angle between vertical line and centre of
the kingpin when viewing from the front of
the vehicle. It varies from 3.5 to 7.5 degrees
• Effect: Both kingpin inclination and castor give
directional stability.
• Particulary steering effort is reduced when the
vehicle is stationary.
• Tyre wear also is greatly reduced.

14. TOE-IN
The amount Toe-in does not exceed 3mm

15. Steering gears
• Rotary motion of the steering wheel is converted
into straight line motion of the linkage by the
steering gear.
• Two types of steering gears
• 1.The pitman-arm type and
• 2.The rack-and-pinion type
• Steering gear converts the turning motion of the
steering wheel into to and fro motions of the link
rod of the steering linkage.
• Steering gear assembly not only steers from
wheels but it also reduces the steering wheel
turning effort by increasing the output torque.
• The reduction ratio is known as steering ratio.

16. Steering gear box & types
• Worm and roller
• Worm and sector
• Cam and roller
• Cam and peg
• Cam and turn lever
• Screw and nut
• Recirculating ball
• Rack and pinion
• Worm and ball bearing

17. Recirculating Ball Type Steering Gear
Box

18. Rack and Pinion type Steering Gear
Box

19. Cam and Roller Type

20. Cam and lever type steering gear

21. Cam and peg type steering gear

22. Ackerman - Jeantaud Steering Linkage

23. Steering linkages for independent
front suspension

24. • Steering ratio:
• Number of turns on the steering wheel required
to produce one turn of the steering gear cross
shaft. (OR) the ratio of the output force to the
input force applied.
• The number of degrees through which the
steering wheel is turned is divided into number of
degrees for which front wheels turn is known as
overall steering ratio.
• The steering ratio ranges from 11:1 to 24:1 in
passenger car having no power steering.
• This ratio varies from 15 to 20% higher than
steering gear ratio in both manual steering &
power steering.

25. • Steering gear ratio: The ratio between number of
degrees of rotation on the steering wheel and
number of degrees through which the cross shaft
is free to rotate at the same time.
• High steering ratio is called slow steering because
the steering wheel has to be turned for many
degrees to obtain a small steering effect.
• Low steering ratio is called fast or quick steering
because the steering wheel has to be turned to
obtain a large effect.
• There are two factors:
• 1. Steering linkage ratio, and
• 2. Gear ratio in the steering gear

26. • Steering linkage ratio is determined by the
relative length of the pitman arm and the steering
arm.
• If the effective lengths of the pitman arm and the
steering arm are equal, the linkage has a ratio of
1:1.
• If the pitman arm is shorter than steering arm ,
the linkage ratio will be less than 1:1.

27. • Some disadvantages in manual steering:
• It is bigger and heavier in engines on cars
• Low pressure tyres should be used in case of cars.
• The larger steering ratio is required to steer these
cars. For more turns of the steering wheel are
required to move to the desired distance.
• Power steering system uses compressed air,
electrical devices and hydraulic pressure.
• Hydraulic oil pressure is used in all cars an most
trucks having power steering systems.
• Power steering is to improve the driving comfort.

28. • POWER STEERING

29. Straight ahead position

30. Turning position

31. FRONT AXLE
• The major unit on front part of a motor vehicle
is the front axle.
• It takes the weight of the front portion of the
automobile. It gives steering facility and absorbs
shocks.
• The weight of the front part of the vehicle is
transmitted to the road surface through front
wheels by the front axle of a vehicle.
• It also houses the mechanism for steering the
vehicle to absorb shocks due to road surface
variations.

32. Functions of front axle:
• It turns the front wheel easily
• It provides a cushioning effect though a spring
• It takes the weight of front vehicle
• It provides steering action
• The spring transmits cushion effect to the vehicle
• It controls the ride through shock absorber
• It takes the braking system
• It transmits power to the front wheels in case of
four wheel drive
• It carries both the hub and wheels

33. Construction and Components of Front
Axle

34. Axle beam
Axle beams are made by drop forging of steel having 0.4% carbon or 1-3% nickel steel
The centre portion of the front axle is provided a downward sweep to maintain the chassis
height low.

35. Types of Front Axles
The front axis are called dead axles when they do not rotate but live axles transmit
power to rear wheels.
A live front axle also transmits the driving power to front wheels having different
swiveling mechanisms.

36. Stub axle:
• The steering have to turn the front wheel. It is done by
hinging the stub axle with steering knuckle at the axle
beam.
Types of stub axle:
• Elliot: It is connected to the front stub axle by placing in
the yoke end with a kingpin and cotter is used to join these
together
• Reversed elliot: the arrangement is reversed. The kingpin if
fixed in the axle beam. Its ends turn in the forks of the
steering knuckle.
• Lamoine:L shaped spindle is used instead of yoke type
hinge.
• Reversed lamoine: The construction is similar to the
lamoine stub axle but the upside of the axle is inverted so
that the wheel axle is below the axle beam. Modern
vehicles the front axles are straight.

38. SUSPENSION SYSTEM:
• Chassis of vehicle is connected to the front and rear
through the medium of springs, shock absorbers and
axles. All parts perform the function of protecting
parts from shocks .
• Suspension system has a spring and damper. The
energy of road shock produced by the spring
oscillates. These oscillations are arrested by the
damper knows as shock absorber.
• Spring: used to shocks from road surface
• Dampers: shock absorbers used to improve a riding
comport
• Stabilizer: sway bar or anti roll bar is to prevent
lateral swinging of the car
• A linkage system to control the longitudinal and
lateral movements of wheels.

39. • Function of suspension system:
• To eliminate road shocks from transmission to
vehicle components
• To keep the proper steering geometry
• To obtain a particular height to body structure
• To resist the torque and braking reactions
• To minimize the effects of stresses due to road
shocks on the mechanism & provide a
cushioning effect
• To prevent the structure of the vehicle from
shock loading and vibration due to irregularities
of the road surface
• To obtain the requisite height to body structure

40. Principles of Suspension System
The principles of the suspension system are due
to springing action of motor vehicles.
1. Supporting the weight of vehicle.
2. Absorbing satisfactorily larger and smaller
road impacts with the help of a single
springing device.
3. The reduction of rolling or pitching of the
body to a minimum design and attachment of
springs.

41. Basic Suspension Movements

42. Bouncing
• The vertical movement of the complete body
is called bouncing

43. Pitching
• Recking chair action or rotating action about a
transverse axis through the vehicle parallel to
ground is known as pitching.
• Due to this, the front suspension will move
out of phase thereby resulting a rocking
effect.

44. Rolling
• The movement of the wheel about
longitudinal axis produced by centrifugal force
when cornering is known as rolling.
• It results the body rolling in the lateral which
means side-to side direction.

45. Yawing
• Yawing is the movement of the car's
longitudinal centerline to the right and left in
relation to the car's center of gravity.
• On roads where pitching occurs, there will be
a chance to occur yawing.

46. • Sprung Weight and Unsprung Weight:
• Sprung: the body of vehicle is supported by spring. The weight
of the body is supported by springs called sprung.
• Wheels, axles and other parts of the automobile which are not
supported by spring called the unsprung.
Types of suspension springs:
1. Steel springs:
a. Leaf springs, b. Tapered leaf springs
b. Coil springs, 4. Torsion bar
2. Rubber springs:
a. Compression springs b. Compression – shear spring
c. Steel reinforced springs, d. Progressive spring
e. Face shear spring
3. Air springs
a. Bellow type springs, b. Piston type spring
4. Plastic spring.

47. • Leaf Spring Suspension
It has a number of leaves of increasing lengths made of steel plates.
The spring eye is mounted to the frame by a pin called shackle pin.
The centre portion of the spring is attached to the front axle by a V-bolt.
One end of the spring is mounted on the frame with a simple pin.
The other end is mounted by a shackle with the frame.

48. • Length of the spring: shorter spring will have
higher stiffness
• Width of the spring: wider spring will have higher
stiffness
• Thickness of the leaf: Thicker leaf will have higher
stiffness
• Number of leaves: greater the number of leaves
higher the stiffness
• Types of spring:
• Semi elliptical spring, Quarter elliptical, three
quarter elliptical, full elliptical, transverse spring,
Platform type spring.

49. Types of leaf springs

50. Helper springs
• Helper springs are used along with the main leaf springs on many
commercial vehicles . It is more suitable for a wide range of loading.
Helper springs are mainly provided on rout suspension.
• When the load on the road wheel increases, ends of the helper
spring is just made to touch the special brackets fitted to the side
member thereby operating the helper spring

51. Coil Spring

52. • Coil spring:
• Coil wire if a steel wire
• Required length is coiled throughout
• Coil springs are used both rear & front independent
suspensions
• Energy stored per unit volume is twice in the coil
spring compared to leaf spring
• Coil spring carries both shear and bending stresses
but torque reaction & side thrust cannot be carried
out.
• Both driving reaction and braking torque are also
considered in arranging the coil spring.
• Two types:
• Tension, and Compression spring.

54. • Torsion bar is a steel bar operated by both twisting and
shear stress
• Two long steel bars form springs
• Torsion bar can be used with independent suspensions
• When the wheel strikes a bump, it will start to vibrate up
and down thereby producing torque on the torsion bar
called spring.
• Torsion bar spring is lighter in Wt compared to leaf spring
• It also occupies less space
• Torsion tubes replace torsion bars in many cases
• Main Disadvantages: Does not carry the braking or driving
torque
• Additional linkages are needed
• Absence of friction force, damping is required to absorb
road shocks.

55. • Air suspension system:
• Air springs are used in air suspension systems
• Metal spring is removed & an air bag referred to an
air spring, is inserted or fabricated to fit in the place
of the factory spring
• Air pressure is supplied to the air bag, the
suspension can be adjusted either up or down
• Air spring is nothing but a flexible bellows made for
textile-reinforced rubber, containing compressed air
which is used to carry load on vehicles.
• Air pressure inflates the bellows and raises the
chassis from the axle
• Used on many heavy duty trucks , trailers and buses

59. Shock Absorber
Purpose
(i)To control the vibrations on springs.
(ii) To provide comfortable ride.
(iii) To act flexible and to be rigid enough
(iv) To resist the unnecessary motion of the
spring.

60. Types of shock absorbers
• 1. Mechanical shock absorber (friction type)
• 2 Hydraulic shock absorbers

61. Telescopic Shock Absorber

62. Advantages of telescopic shock
absorber
• 1. Large amount of energy is dissipated due to
large volume of fluid displaced without causing a
high temperature rise.
• 2. There is no wear development in the damper
with the absence of connecting arm pivots.
• 3. The leakage is very less due to lower pressure
and absence of the rotating shaft enteringthe
reservoir.
• 4. Cost is less than springs.

63. Types of Suspension System
(i) Front end suspension
(a) Independent front suspension
(b) Rigid axle or conventional front suspension
(ii) Rear end suspension
(a) Longitudinal leaf spring rear suspension
(b) Transverse leaf spring rear suspension
(c) Coil spring rear end suspension.

64. Longitudinal independent front
suspension

65. Transverse independent front
suspension

66. Mac Pherson strut and link type
independent front suspension

67. Wishbone type independent
suspension with coil spring

68. Rigid Axle Front Suspension

69. BRAKING SYSTEM
• The mechanism which is used to slow down and
stop the vehicle is known as braking system
Need for brakes:
1. To stop or slow down the vehicle at the will of an
operator.
2. To control the vehicle descending a hill.
3. To keep the vehicle in a desired position even at
rest.
4. To park the vehicle and hold it in stationary
position without the presence of driver

70. Types of Brakes
1. According to the applications:
(i) Service or running or foot brake
(ii) Parking or emergency or hand brake.
2. According to the number of wheels:
(i) Two wheel brakes
(ii) Four wheel brakes.
3. According to the brake gear:
(i) Mechanical brake
(a) Hand brake
(b) Foot brake
(ii) Power brake:
(a) With booster.
(b) Without booster.
4. According to construction
(i) Drum brake
(ii) Disc brake.
5. According to location
(i) Transmission brakes
(ii) Wheel brakes.

71. Types of Brakes
6. According to method of braking contact:
(i) Internal expanding brakes
(ii) External expanding brakes.
7. According to the power unit:
(i) Cylinder brake
(ii) Diaphragm brake.
8. According to power transmission:
(i) Direct acting brake
(ii) Geared brake.
9. According to method of applying brake force:
(i) Single acting brake
(ii) Double acting brake.
10. According to power employed:
(i) Vacuum brakes
(a) Atmospheric suspended
(b) Vacuum suspended
(ii) Air or pneumatic brakes
(iii) Hydraulic brakes
(iv) Hydrostatic brakes
(v) Electric brakes.

72. DRUM BRAKE
A brake drum is connected to the wheel and also a back plate is mounted on the axle
casing.
Two brake shoes are connected on the back plate. Friction linings, called brake linings,
are provided on brake shoes

73. DISC BRAKES

74. Fixed caliper disc brake

75. Hydraulic Brakes
• Hydraulic braking system consists of two main
components which are master cylinder and
wheel cylinder.
• The master cylinder is attached to the wheel
cylinder by tubes on each of four wheels.
• The system has light liquid pressure which acts
as a brake fluid.

76. HYDRAULIC CYLINDER

77. • When the pressure attains the upper limit, this valve get
opened to allow air to the atmosphere
• Brake valve is connected to the driver pedal which controls
the air pressure acting on four brake chambers
• When the driver releases the brake pedal, force is exerted
on spring and piston
• Exhaust valve seat will also move downward when the
piston moves downwards to contact the exhaust valve and
seals the exhaust opening in the piston stem
• Driver releases the pedal fully the graduated spring is
compressed and strike by the piston shoulder in the body.
• The inlet valve is fully opened and full air tank pressure is
admitted to pass through brake valve into the brake
chamber

78. Master cylinder:
Purpose:
• The required hydraulic pressure is built up to operate
the system
• It maintains a constant volume of fluid in the system
• To bleed or force air out of the brake line and wheel
cylinder, a pump is used.
Main parts of a mater cylinder:
• Brake fluid reservoir
• Cylinder or compression chamber
• Piston assembly
• Check valve or control valve
• Piston return spring

79. MASTER CYLINDER

80. Working of master cylinder

81. Wheel cylinder
The following are the functions of wheel cylinder.
1. It actuates the shoes outward to contact the brake drum.
2. It converts the hydraulic pressure of very low value into a significant value of
mechanical force of higher value.

82. Pneumatic Braking System
Advantages of pneumatic brakes:
1. It is more effective when compared to other brakes.
2. The air brake parts are easily located where the chassis
design making is simple.
3. The compressed air can be used for tyre inflation wipers,
horn and other accessories.
4. It employs only air as the working medium which is easily
available.
5. It is easy to store air at high pressure.
6. It provides heavy braking effect used in heavy vehicles and
trucks.
7. It provides better control.
8. It reduces the stopping distance.
9. It mainly allows less wear and tear of parts.
10. It has flexible hose connection.

83. PNEUMATIC BRAKES

84. VACCUM SERVO BRAKE

85. ANTILOCK BRAKING SYSTEM(ABS)
• Stopping safely is one of the most important
functions a motor vehicle.
• Antilock brake system (ABS) prevents the
wheels of a vehicle brake from locking when
the brakes are applied suddenly, thus it avoids
skidding and maintain the ability to steer a
vehicle.
• The locking of wheels of a vehicle is extremely
dangerous on wet or icy roads.

86. ANTILOCK BRAKING SYSTEM(ABS)

87. ANTILOCK BRAKING SYSTEM(ABS)

88. Components of ABS:
• Wheel speed sensors(pick up and exciter)
• Electronic control unit(ECU)
• Hydraulic modulator valves
• Pump motor and accumulator
• Wheel speed sensors: consists of magnetic pickup and
toothed sensor ring are mounded in steering knuckles,
wheel hub, brake backing plates, differential housing.
Wheel speed sensor pickup has a magnetic core
surrounded by coil windings. When wheel turns, teeth
on the sensor ring move through the pickup magnetic
field. The number of voltage pulses per second is
induced in the pickup change in direct proportion to
the wheel speed.

89. • ECU: ECU processes all ABS information and signal
functions. It receives and interprets voltage pulses
generated by the sensor pickup as the exciter
teeth pass by and its uses this information.
• Hydraulic modulator valve: Valves regulate the
fluid pressure to brake during ABS action. ECU
commands the modulator valve to either
Change the fluid pressure to the brake chamber
Hold the existing pressure
ABS solenoid valves for each brake circuit. The
exact number of valves per circuit depends on
ABS system.

90. Advantages of ABS:
(i) ABS guarantees the stable braking characteristics on all road
surfaces. Hence, it avoids overturning of the vehicle.
(ii) It reduces friction on wheels and road. Thus, increases
efficiency of tires up to 30%.
(iii) Although ABS will not decrease a vehicle's stopping
distance compared to an identical non-ABS vehicle, it
ensures the shortest distance in which a vehicle can be
brought to rest.
(iv) ABS is particularly effective in wet or icy roads upon which
a vehicle is much more likely to skid.
(v) Steering control is effective, i.e., vehicle can be steered
smoothly while braking. Thus, it minimizes the accidents.
(vi) A driver without experience can drive ABS vehicle
effectively than an experienced driver on the non-ABS
vehicle.

91. Electronic Brake Force Distribution
(EBD)
• EBD (Electronic Brake Force Distribution) is a technology that enables the
braking force of a vehicle to be increased or applied automatically
depending on road conditions, speed of the vehicle, weight of vehicle, etc.

92. TRACTION CONTROL
• A Traction Control System (TCS) also known as
Anti-Slip Regulation (ASR) is typically a
secondary function of ABS.
• The primary function of the traction control
system is to maintain the traction and stability
of the vehicle regardless of the road surface
condition.
• It is achieved by reducing the drive torque
applied to rear wheels to eliminate the wheel
slip.

93. TRACTION CONTROL