05-04-2010, 11:09 AM
Suspension system in automobiles
Presented BY ,
SAGAR BABU-06J61A0318
What is suspension system
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to
its wheels
Serve a dual purpose “ contributing to the car's handling and braking.
Protects the vehicle itself and any cargo or luggage from damage and wear
Different suspension systems
Conventional suspension system
Independent suspension system
Air suspension system
Hydro elastic suspension system
Conventional suspension system
Two wheels are mounted on either side of the rigid axle
When one wheel encounters the bump, both the wheel do not execute parallel up and down motion
So it gives rise to gyroscopic effect and wheel wobble
Rear driving wheels mounted on live axle suspended by laminated leaf springs and shock absorbers
Independent suspension system
Both the front and the rear wheel are utilized
Design incorporated in the front wheels
One wheel goes down ,the other wheel does not have much effect
Basic classification of the design
MacPherson Strut
Double Wishbone
Multi link
the most widely used front suspension system in cars
comprises of a strut-type spring and shock absorber combo, which pivots on a ball joint on the single, lower
arm.
The steering gear is either connected directly to the lower shock absorber housing, or to an arm from the front
or back of the spindle (in this case
When you steer, it physically twists the strut and shock absorber housing (and consequently the spring) to turn
the wheel
DOUBLE WISHBONE SUSPENSION
Type of double-A or double wishbone suspension
Wheel spindles are supported by an upper and lower 'A' shaped arm.
The lower arm carries most of the load.
If you look head-on at this type of system, parallelogram system that allows the spindles to
travel vertically up and down.
This side-to-side motion is known as scrub
Type of double-A arm suspension although the lower arm in these systems can sometimes be replaced with a single
solid arm (as in my picture).
The spring/shock combo is moved from between the arms to above the upper arm.
This transfers the load-bearing capability of the suspension almost entirely to the upper arm and the spring
mounts.
The lower arm in this instance becomes a control arm.
Multi-link suspension
It's currently being used in the Audi A8 and A4 amongst other cars.
The basic principle of it is the same, but instead of solid upper and lower wishbones, each 'arm' of the
wishbone is a separate item.
These are joined at the top and bottom of the spindle thus forming the wishbone shape.
The super-weird thing about this is that as the spindle turns for steering, it alters the geometry of the
suspension by torquing all four suspension arms.
Spring is separate from the schock absorber.
Advantages ( independent front )
Bigger deflection of front wheels, no reaction on steering
Greater distance for resisting rolling action
Front axle (small-stub), improves road holding tendency of tyres.
Minimum vibrations
DISADVANTAGES
Better shock absorber required.
Expensive
Tyre wear increases due to transmission of torque.
Advantages ( independent rear suspension)
Lesser unsprung weight “ improves ride , reduces tyre wear.
Increased passenger space
Rear wheels remain stable ..
DISADVANTAGES
Increased cost
Complicated design
Steering action is not proper
Traverse suspension system
Normally find on the rear suspension
Combines independent double wishbone suspension with a leaf spring.
It involves one leaf spring mounted across the vehicle, connected at each end to the lower wishbone.
The centre of the spring is connected to the front subframe in the middle of the car.
There are still two shock absorbers, mounted one to each side on the lower wishbones.
Air suspension
Comprises of compressor , suppling air to air tank
Pressure maintained “ 5.6 to 7 kg/sq.m
Air bags “ on each wheel
As load applied , air bags compressed actuating the levelling valve .
Air from the tank fills the compressrd air bag & hence raise the level of the frame.
Air from air bag gets released as load on chassis decreases .
Air suspension layout
Advantages of air suspension
These maintain a constant frequency of vibration whether the vehicle is laden or unladen.
Constant frame height is maintained.
It helps to reduce the load while the vehicle in motion i.e. the dynamic loading as the spring rate variation
between laden and unladen weight is much less.
It gives smooth and comfort ride of the vehicle.
The stiffness of the system increases with the increase of the deflection.
Common Air Suspension Problems
Air bag or air strut failure
- due to old age, or moisture within the air system that damages them from the inside.
Compressor failure
- Primarily due to leaking air springs or air struts
- Compressor burnout may also be caused by moisture from within the air system coming into contact with its
electronic parts.
Dryer failure
- which functions to remove moisture from the air system eventually becomes saturated and unable to perform
that function
Hydrolastic Suspension
a system where the front and rear suspension systems were connected together in order to better level the car
when driving.
The front and rear suspension units have Hydrolastic displacers, one per side.
These are interconnected by a small bore pipe. Each displacer incorporates a rubber spring
Damping of the system is achieved by rubber valves.
when the front wheel encounter bumps ,the piston moves upwards pressurising the fluid to enter into the rear
unit.
Hydroelastic was eventually refined into Hydragas suspension.......
Hydrogas suspension
Known as hydro-pneumatic suspension.
The difference is in the displacer unit itself.
In the older systems, fluid was used in the displacer units with a rubber spring cushion built-in.
With Hydragas, the rubber spring is removed completely.
The fluid still exists but above the fluid there is now a separating membrane or diaphragm, and above that is a
cylinder or sphere which is charged with nitrogen gas.
The nitrogen section is what has become the spring and damping unit whilst the fluid is still free to run from
the front to the rear units and back.
Difference ¦
HELPER SPRING
DIRECTLY MOUNTED ON MAIN SPRINGS
TAKE CARE OF LARGE VARIATION IN SPRING LOAD
DURING LIGHT LOADS ,ONLY MAIN SPIRNG IS ACTIVE , AS LOAD INCREASE TO A PARTICULAR FIXED VALUE , BOTH THE
SPRINGS ARE ACTIVE
Presented BY ,
SAGAR BABU-06J61A0318
What is suspension system
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to
its wheels
Serve a dual purpose “ contributing to the car's handling and braking.
Protects the vehicle itself and any cargo or luggage from damage and wear
Different suspension systems
Conventional suspension system
Independent suspension system
Air suspension system
Hydro elastic suspension system
Conventional suspension system
Two wheels are mounted on either side of the rigid axle
When one wheel encounters the bump, both the wheel do not execute parallel up and down motion
So it gives rise to gyroscopic effect and wheel wobble
Rear driving wheels mounted on live axle suspended by laminated leaf springs and shock absorbers
Independent suspension system
Both the front and the rear wheel are utilized
Design incorporated in the front wheels
One wheel goes down ,the other wheel does not have much effect
Basic classification of the design
MacPherson Strut
Double Wishbone
Multi link
the most widely used front suspension system in cars
comprises of a strut-type spring and shock absorber combo, which pivots on a ball joint on the single, lower
arm.
The steering gear is either connected directly to the lower shock absorber housing, or to an arm from the front
or back of the spindle (in this case
When you steer, it physically twists the strut and shock absorber housing (and consequently the spring) to turn
the wheel
DOUBLE WISHBONE SUSPENSION
Type of double-A or double wishbone suspension
Wheel spindles are supported by an upper and lower 'A' shaped arm.
The lower arm carries most of the load.
If you look head-on at this type of system, parallelogram system that allows the spindles to
travel vertically up and down.
This side-to-side motion is known as scrub
Type of double-A arm suspension although the lower arm in these systems can sometimes be replaced with a single
solid arm (as in my picture).
The spring/shock combo is moved from between the arms to above the upper arm.
This transfers the load-bearing capability of the suspension almost entirely to the upper arm and the spring
mounts.
The lower arm in this instance becomes a control arm.
Multi-link suspension
It's currently being used in the Audi A8 and A4 amongst other cars.
The basic principle of it is the same, but instead of solid upper and lower wishbones, each 'arm' of the
wishbone is a separate item.
These are joined at the top and bottom of the spindle thus forming the wishbone shape.
The super-weird thing about this is that as the spindle turns for steering, it alters the geometry of the
suspension by torquing all four suspension arms.
Spring is separate from the schock absorber.
Advantages ( independent front )
Bigger deflection of front wheels, no reaction on steering
Greater distance for resisting rolling action
Front axle (small-stub), improves road holding tendency of tyres.
Minimum vibrations
DISADVANTAGES
Better shock absorber required.
Expensive
Tyre wear increases due to transmission of torque.
Advantages ( independent rear suspension)
Lesser unsprung weight “ improves ride , reduces tyre wear.
Increased passenger space
Rear wheels remain stable ..
DISADVANTAGES
Increased cost
Complicated design
Steering action is not proper
Traverse suspension system
Normally find on the rear suspension
Combines independent double wishbone suspension with a leaf spring.
It involves one leaf spring mounted across the vehicle, connected at each end to the lower wishbone.
The centre of the spring is connected to the front subframe in the middle of the car.
There are still two shock absorbers, mounted one to each side on the lower wishbones.
Air suspension
Comprises of compressor , suppling air to air tank
Pressure maintained “ 5.6 to 7 kg/sq.m
Air bags “ on each wheel
As load applied , air bags compressed actuating the levelling valve .
Air from the tank fills the compressrd air bag & hence raise the level of the frame.
Air from air bag gets released as load on chassis decreases .
Air suspension layout
Advantages of air suspension
These maintain a constant frequency of vibration whether the vehicle is laden or unladen.
Constant frame height is maintained.
It helps to reduce the load while the vehicle in motion i.e. the dynamic loading as the spring rate variation
between laden and unladen weight is much less.
It gives smooth and comfort ride of the vehicle.
The stiffness of the system increases with the increase of the deflection.
Common Air Suspension Problems
Air bag or air strut failure
- due to old age, or moisture within the air system that damages them from the inside.
Compressor failure
- Primarily due to leaking air springs or air struts
- Compressor burnout may also be caused by moisture from within the air system coming into contact with its
electronic parts.
Dryer failure
- which functions to remove moisture from the air system eventually becomes saturated and unable to perform
that function
Hydrolastic Suspension
a system where the front and rear suspension systems were connected together in order to better level the car
when driving.
The front and rear suspension units have Hydrolastic displacers, one per side.
These are interconnected by a small bore pipe. Each displacer incorporates a rubber spring
Damping of the system is achieved by rubber valves.
when the front wheel encounter bumps ,the piston moves upwards pressurising the fluid to enter into the rear
unit.
Hydroelastic was eventually refined into Hydragas suspension.......
Hydrogas suspension
Known as hydro-pneumatic suspension.
The difference is in the displacer unit itself.
In the older systems, fluid was used in the displacer units with a rubber spring cushion built-in.
With Hydragas, the rubber spring is removed completely.
The fluid still exists but above the fluid there is now a separating membrane or diaphragm, and above that is a
cylinder or sphere which is charged with nitrogen gas.
The nitrogen section is what has become the spring and damping unit whilst the fluid is still free to run from
the front to the rear units and back.
Difference ¦
HELPER SPRING
DIRECTLY MOUNTED ON MAIN SPRINGS
TAKE CARE OF LARGE VARIATION IN SPRING LOAD
DURING LIGHT LOADS ,ONLY MAIN SPIRNG IS ACTIVE , AS LOAD INCREASE TO A PARTICULAR FIXED VALUE , BOTH THE
SPRINGS ARE ACTIVE
