SUSPENSION & Principles of suspension

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems serve a dual purpose — contributing to the vehicle's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations,etc. These goals are generally at odds, so the tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

Types of Suspension

solid beam axle:

in the beam axle setup both of the front wheels are connected to each other by a solid axle. 




beam alxe suspension




Solid-axle coil spring suspension

 Swing alxe

 the axles pivot about a location somewhere near the center of the car and allow the wheels to travel up and down through their respective arcs.

swing alxe

 trailing link suspension

 uses a set of arms located ahead of the wheels to support the unsprung mass

MacPherson

This strut based system, where the spring/shock directly connects the steering knuckle to the chassis and acts as a link in the suspension, offers a simple and compact suspension package

equal length A-arm   &  unequal length double A-arm

Principles of suspension

The suspension system isolates the body from road shocks and vibrations which would otherwise be transferred to the passengers and load.
It also must keep the tires in contact with the road. When a tire hits an obstruction, there is a reaction force. The size of this reaction force depends on the unsprung mass at each wheel assembly.
The sprung mass is that part of the vehicle supported by the springs - such as the body, the frame, the engine, and associated parts.
Unsprung mass includes the components that follow the road contours, such as wheels, tires, brake assemblies, and any part of the steering and suspension not supported by the springs.
Vehicle ride and handling can be improved by keeping unsprung mass as low as possible. When large and heavy wheel assemblies encounter a bump or pothole, they experience a larger reaction force, sometimes large enough to make the tire lose contact with the road surface.
Wheel and brake units that are small, and light, follow road contours without a large effect on the rest of the vehicle.
At the same time, a suspension system must be strong enough to withstand loads imposed by vehicle mass during cornering, accelerating, braking, and uneven road surfaces.