For several years vehicle dynamics engineers have struggled to accomplish a compromise between vehicle handling, ride comfort and stability. The outcomes of this are vibrant in the vehicles we see today. In common, at one extreme are large sedan and luxury cars with excellent ride qualities but only satisfactory handling behavior. On the last end of the spectrum are sports cars with very good handling but very firm ride quality. In between is any number of variations dictated by the vehicle manufacturer and target customer needs.
Every automotive suspension has two objectives: passenger comfort and vehicle control. Comfort is delivered by isolating the vehicle’s passengers from road disturbances like bumps or holes. Control is attained by maintaining the car body from rolling and pitching extremely and maintaining good contact stuck between the tire and the road. By and large, today’s vehicle suspensions use hydraulic dampers and springs that are charged with the tasks of absorbing bumps, decreasing the car’s body motions during accelerating, braking and turning and keeping the tires in contact with the road surface.
History of suspension systems
1903 – Mors from Germany fixed a car using shock absorbers.
1920 – Leyland used torsion bars in their suspension system.
1922 – Unitary constructions and independent front suspension were initiated on the Lancia Lambda.
1932 – By this year ,the independent front suspension became common in standard cars.
1948 – Triumph Mayflower presented the combined coil spring/damper unit.
1950 – Ford implemented the McPherson strut independent front suspension on MK 1 consul.
1959 – Usage of independent rubber suspension started.
1962 – Introduction of the hydrostatic suspension.
Why do vehicles have suspension?
The purpose of a suspension system is to isolate the body and its residents from the irregularities of the road surface. In an ideal world the body should ride level and lacking vertical motion however bumpy the road surface. Another significant feature of suspension is that it should retain the tires on the ground all the time. If there were not at all suspension the tires would incline to lift off the ground every time they passed over a bump at the same time, the shock as the wheels left the ground’ and then came down another time, would be transferred precise to the passengers.
What does a suspension system do?
Preferably the suspension should allow the wheels to move up and down so that they follow the undulations in the road during the body rides level. The first necessity therefore is that the wheels should be capable of moving vertically relative to the body. All suspension has this wheel travel, which must be housed by some means.
Functions of suspension system
The vehicle suspension system is mainly responsible for driving comfort and safety as the suspension carries the vehicle body and transmits all forces between the body and the road.
In order to completely influence these properties, semi-active and active components are introduced. These aid the suspension system to adapt to various driving conditions.
By addition of a variable damper and spring, driving comfort and safety are considerably improved related to suspension setups with fixed properties.
To prevent the road shocks from existence transmitted to the vehicle frame. To preserve the stability of the vehicle in pitching or rolling. To maintain the occupants from road shocks. To provide good road holding while driving, cornering and braking.
Broad Classification of suspension system
Suspension systems can be generally classified into two subgroups: dependent and independent. These terms denote to the ability of opposite wheels to move independently of each other.
A dependent suspension usually has a beam or live axle that holds wheels parallel to each other and perpendicular to the axle. When the camber of one wheel differs the camber of the opposite wheel changes in the same way (by convention on one side this is a positive change in camber and on the other side this a negative change).
An independent suspension permits wheels to rise and fall on their own without disturbing the opposite wheel. Suspensions with other devices like sway bars that link the wheels in some way are still classed as independent.
A third type is a semi–dependent suspension. In this type, the motion of one wheel does disturb the position of the other but they are not firmly attached to each other. A twist beam rear suspension is such a kind of system.