Suspension system

1. ActivityTask 104-1

2. PURPOSE OFTHE SUSPENSION SYSTEM
• The suspension system is located between the wheel axles and the vehicle body
or frame.
• It allows the vehicle to travel over rough surfaces with a minimum of up-and-
down body movement.
Its purpose is to:
1. Support the weight of the vehicle.
2. Cushion bumps and hole in the road.
3. Maintain traction between the tires and the road.
4. Holds the wheels in alignment.

3. COMPONENTSOF SUSPENSION SYSTEM
• The suspension system component includes the springs and related
parts that support the weight of the vehicle body on the axles and
wheels.
• The springs and the shock absorbers are the two main parts.
• Shock absorbers allow the basic springs movement, but quickly
dampen out the unwanted bouncing that follows.

4. Shock absorber and Coil spring

6. TYPES OF SPRINGS
• Four types of springs are used in automotive suspension system.
These are coil, leaf, torsion bar, and air spring.

7. • COIL SPRING
- Is made of a length of round spring-steel rod wound into a coil.
- As the string is compressed, its resistance to further compression
increases.

8. LEAF SPRING
• Two types of leaf spring are single-leaf and multi leaf springs.
• In operation, the spring bends to absorb road shocks. The plates bend
and slide on each other to permit this action.

9. TORSION BAR
• Is as straight rod of spring steel, rigidly fastened at one end to the vehicle frame or body. The other end attaches to
an upper or lower control arm .
• As the control arm swings up and down in response to wheel movement, the torsion bar twists to provide spring
action.

10. AIR SPRING
- Is a rubber cylinder or air bag filled with compressed air.
- A plastic piston on the lower control arm moves up and down with the lower control arm. This
causes the compressed air to provide spring action.

11. SPRUNGAND UNSPRUNGWEIGHT
• The total weight of the vehicle includes the sprung weight and the
unsprung weight.
• The sprung weight is the weight supported by springs.
• The unsprung weight is the part not.

12. SPRING RATE
• The softness or hardness of a spring is its spring rate.
• This is the load required to move a spring that compresses uniformly
(a linear-rate spring) is the weight required to compress it 1 inch.

13. CONTROLLING SPRINGACTION
• The ideal spring for automotive suspension absorbs road shock rapidly
and the returns to its normal position slowly.
• A very flexible or soft spring allows too much movement.
• A stiff or hard spring gives too rough a ride.
• A medium-soft spring and a shock absorber produce satisfactory ride.
• The shock absorber prevents spring override.

14. PURPOSE OF SHOCKABSORBERS
• A shock absorber is a tubular hydraulic device placed near each wheel
to control or dampen spring oscillations.
• One end is attached to the vehicle body or frame. The other end
attaches to a moving suspension part such as axle housing or a control
arm.
• It doesn’t support the weight of the vehicle, nor does it affect the
height of the vehicle.

16. SHOCK-ABSORBER OPERATION
• It is basically an oil-filled cylinder on tube in which a piston moves up
and down.
• This forces the oil or hydraulic fluid in the cylinder to flow through
small fluid passages in the piston.
• The resulting fluid friction limits spring bounce.

17. GAS-FILLED SHOCK ABSORBERS
• There is some air above the fluid in the shock absorber.
• During compression and rebound, the rapid movement of the fluid
between the chambers can mix the air with the fluid. Then the fluid
foams or aerates.
• When the piston moves through air or foam, it meets little resistance.
• Some shock absorbers have a rubber bag or cell that contains the gas
to prevent mixing.

19. OTHERTYPES OF SHOCKABSORBER
• Various vehicles and suspension systems use different types of shock
absorbers. Some shock absorbers can adjust.