a presentation on “ suspension system ”
TRANSCRIPT
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A PRESENTATION on
“ SUSPENSION SYSTEM ”
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Suspension Systems
Topics covered in this presentation: Basic Suspension System Spring Types Suspension System Construction
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Basic Suspension System
allow rapid cornering without body roll when the car leans to one side.
keep tyres in firm contact with the road at all times and conditions.
prevent body squat (tilting down at rear) when accelerating.
prevent body dive (tilting down at front) when braking.
allow front wheels to turn for steering.
keep the wheels vertical and in correct alignment at all times.
The primary purpose of a suspension system is to support the weight of the vehicle and give a smooth ride.
It is desirable that it should also:
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Elementary Suspension System
The steering knuckle is ball-jointed to the control arm to allow for vertical and horizontal movements.
A control arm that pivots on the vehicle frame.
This simple example has a coil spring and built-in shock absorber.
In a modern vehicle, the typical suspension components are:
All of the components are attached to the frame.
Coil spring
Shock absorber
Steering knuckle
Frame
Control arm
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A solid axle tilts with road bumps.
Independent Suspension
This is the preferred system for most modern vehicles.
This causes both wheels to be tilted.
Independent suspension allows one wheel to move up or down without appreciably affecting the other.
The design of the control arm keeps the wheel upright.
Solid axle
Independent suspension
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Coil Spring
There are four main types of springs in common use:
This consists of a spring-steel rod wound into a coil.
It is ideally suited to independent suspension.
This is the most common type of spring used by modern vehicles.
Coil spring
Coil Spring
Coil Spring Leaf Spring Torsion Bar Air Spring
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Leaf Spring
Flat plates of spring steel are bolted together.
This type used to be common but is now only used on a few rear suspension systems.
The front end of the spring is bolted directly to the frame.
A swinging shackle at the rear permits the length of the spring to change when it is flexed.
U-bolts and plates clamp spring to axle housing.
Swinging shackle
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Torsion Bar
A strut rod prevents front or rear movements of the control arm.
When the control arm is moved by the suspension, the twisting motion of the torsion bar resists the movement.
Torsion bar
Strut rod
Control arm
The other end of the torsion bar is attached to the control arm so that it twists as the control arm moves up or down.
One end of the torsion bar is fixed to the vehicle frame.
Vehicle frame
Steering knuckle connects onto control arm
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Air Spring
This is normally a two-ply rubber cylinder filled with compressed air.
It has similar rebound reaction to a coil spring.
Rebound (expansion) allows the control arm to move down when there are hollows in the road surface.
This is especially adaptable to automatic levelling systems.
The air spring is much lighter in weight, compared with its steel sprung equivalent, resulting in increased economy and an adjustable controllable ride.
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Control Arm
A control arm holds the steering knuckle, bearing support or axle housing.
The control arm is connected to the steering knuckle by a ball joint.
Control arm bushes act as bearings.
The control arm is free to move up and down with the suspension.
Rear suspension control arms may have bushes at both ends.
Control arm Steering knuckle
Ball joint
Bushes
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Ball Joints
Ball joints allow limited movement in all directions.
The drive shaft must allow universal movement.
Ball joint is short for ball-and-socket joint.
Two pivots, one above and one below, keep the wheel vertical.
A front wheel system is shown, including a steering knuckle.
Drive shaft
Hub
Steering knuckle
Lower pivot ball joint
Upper pivot ball joint
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Shock Absorber
The function of a shock absorber is to reduce spring oscillations (up and down movements) following a road shock.
The upper end (top mount) is attached to the frame and the lower end (bottom mount) to the suspension unit.
A pressurized gas chamber is sometimes added to prevent air bubbles in the oil causing foaming.
A piston and valve assembly moves in an oil-filled cylinder. Movement is controlled by the valve, rate-of-flow, restriction.
The cylinder is enclosed in a dust cover.
Piston and valve assembly
Oil cylinder
Pressurized gas chamber
Top mount
Bottom mount
Dust cover
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Stabilizer (Sway) Bar
The purpose of the stabilizer bar is to prevent excessive body leaning when turning.
Links both the lower control arms together.
When one end of the bar is deflected in either direction (up or down), the bar tries to pull the other side in the same direction, this has the effect of stabilizing and controlling the suspension.
When cornering, the outside of the body tends to drop, which twists the bar and limits the amount of the sway.
Stabilizer bar
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