Automobile Suspension, Wheels and Tyres
Automobile Suspension, Wheels and Tyres
Automobile Suspension, Wheels and Tyres
Working: When the vehicle came across a bump and wheel is tended to move
up the lower and the upper arm moves up and the coils spring is compressed,
so shock absorber (Damper) damps the vibrations setup in the coil spring due
to road irregularities. After passing over a bump the lower arm comes to its
original position with upper arm. This type of suspension resists up and down
forces that develop after bump, acceleration, braking and cornering.
Wishbone type suspension
Wishbone type suspension
Macpherson suspension system
Mc-pherson strut type independent suspension: In this type, only lower
wishbones are used as shown in fig. A strut containing shock absorber and the
spring carries also the stub axle on which the wheel is mounted. The wishbone
is hinged to the cross member and positions the wheel as well as resists
accelerating, braking and side forces. This system is simple, lighter and keeping
the unsprung weight lower. Further the camber also does not change when the
wheels move up and down. This type of suspension provides the maximum area
in the engine compartment and is, therefore, commonly used on front wheel
drive cars.
The advantages of MacPherson suspension system
1) System is light in weight, which reduces un-sprung weight.
2) Camber does not change when wheel moves up and down.
3) It provides maximum space for engine.
Macpherson suspension system
Air suspension system
Air suspension system
Shock absorber
A shock absorber is a device used to check or damp out the vibrations of the
suspension springs to a comfortable level.
• The resistance to the free oscillation of the springs is obtained in the
damper by causing a fluid to pass at high speed through small holes.
• The energy absorbed depends upon the viscosity of the fluid and appears as
heat in the fluid.
Types of shock absorbers
Classification by operation:
a). Single action shock absorber
b). Multiple action shock absorber.
• Classification by construction:
a). Mono tube shock absorber
b). Twin tube shock absorber
• Classification by working medium
a). Hydraulic shock absorber
b). Gas filled shock absorber
Telescopic shock absorber
Below figure shows a simple Telescopic Shock absorber. There is a fluid in space
above valve assembly (A), below (A) & also in annular space between cylinder
(C) & tube (D), which is connected to the space below valve assembly (B). (H) is
gland in head (J) & any fluid scrapped off by rod (G) is brought down into
annular space through inclined passage shown in head. Eye (E) is connected to
axle, while eye (F) is attached to chassis frame. Fluid generally used in shock
absorbers is a mixture of 60 per cent Transformer oil & 40 per cent Turbine oil.
When car has come across a bump, Eye (E) would move up & thereby the fluid
will pass from lower side of valve assembly (A) to its upper side. Due to pressure
of fluid through rod (G) fluid will be go to underside of valve (B). This passing of
fluid through valve openings provides damping. Similarly for downward motion
of eye (E), fluid will pass upper side of valve assembly (A) to lower side & also
from lower side of valve assembly (B) to its upper side.
Gas filled shock absorbers
Properties of tyres
NON SKIDDING :-Tread pattern on the tyre must be suitably designed
to permit the least amount of skidding.
• UNIFORM WEAR :-To maintain the non-skidding property, the wear
on the tyre tread must be uniform. The ribbed pattern on the tyre
help to accomplish this.
• LOAD CARRYING:-Tyre material and the design must be able to
ensure that the tyre is able to sustain stresses developed in all
conditions.
• CUSHIONING :- Tyre should be able to absorb small high frequency
vibration set up by the road surface and thus providing cushioning
effect.
POWER CONSUMPTION :- The automotive tyre absorb some power
due to friction between the tread rubber and the road surface and
also due to friction loss on account of the tyre being continuously
fixed release, should be least as less as possible.
• TYRES NOISE :- Tyre noise may be in the form of definite pattern sing,
a sequel, or aloud sound, Should be minimum.
• BALANCING :- As a rotating part of automobile, must be balance
statically and dynamically.
Tyre Cutaway
Radial Ply Tyre
1.Inflation
2.Vehicle maintenance
3.Manner of Driving
4.Miscellaneous factors
Under inflation AND Over inflation
Effect of under inflation:
1) Uneven tread wear, more wear at the tyre sides.
2) Lack of directional stability
3) Increased rolling resistance leading to increased fuel consumption
4) The valve may be ripped out due to tyre sides.
Q 160 99 69
70
325
335
98
99
750
775
R 170 106 71 345 100 800
S 180 112 72 355 101 825
T 190 118 73 365 102 850
91 615
92 630
Load Index
93 650
Causes of tyre wear and remedies
Wheel balancing:
It is a process that ensures wheel spins truely as they are fitted on a vehicle. In
case wheel are not spinning properly then there are problems like uneven tyre
wear, a vehicle pulling on one side, excessive bouncing of a vehicle which we
face. To avoid them this is done. Wheel balancing means balancing wheel
around axis around which it rotates.
1.Wheel balancing will ensure a smoother ride and more enjoyable driving.
2.The tires and wheels to spin without causing any vibrations
3.The better wear from the tyres will save you time and money
4.Vibration free that is comfortable to drive in and easy to handling of the
vehicle.
5.Remove stresses and strains on the wheel bearings and suspension
components
6.Steering components can be safe and prevent from failure of prematurely
extreme cases to all the parts
7.Protect from premature wearing of suspension and steering components,
rotating parts and tyres.
8.Save from any dangerous and expensive