affects both the driver's control of the car and the comfort of the occupants. The springs allow the wheels to move up to absorb bumps in the road and reduce jolting, while the
prevent bouncing up and down. Various mechanical links keep the wheels in line.
Types of spring
Most cars have steel springs, and the oldest type is the
. The topmost and longest strip, the master leaf, is curled at each end into an eye by which it is connected to the
. The leaves below are progressively shorter and less curved.
As the spring deflects, it flattens, causing the second leaf to touch the master leaf, then the third to touch the second. The spring thus becomes progressively stiffer. Such a spring gives a smoother ride than a stiff, plain single leaf could.
In some cars the multi-leaf spring has been replaced by a special single leaf that is tapered in section and has progressive stiffness as it is deflected.
is simply a spiral of resilient steel rod. It is stretched or compressed by the vertical movement of the wheels.
is a length of
with splined or square ends. One splined end is fixed to a
arm that forms part of the suspension. The bar rotates as the lever arm moves up and down.
The other splined end is fixed to the frame. The
stop the bar turning in its fixings. Instead, the bar has to twist as the suspension deflects.
In all forms of steel spring, the
set up by road shocks are stored by the spring deflection rather than passed on to the passengers. The forces are then released gradually to restore the car to a level ride.
Rubber springs can perform the same function, but they do not store as much
and are therefore used on light vehicles only.
A form of
suspension can be combined with rubber springs to refine the system. Up-and-down movement of the wheel
fluid from one chamber to another through a damper
. Each chamber has a flexible
on the other side of it.
The gas is compressed further as fluid comes into the chamber through the valve. In effect the gas is acting as a pneumatic spring.
There is usually a link tube through which some of the fluid pumped out of a front-wheel chamber travels to the rear wheel on the same side to equalise the suspension.
Citroen hydraulic suspension can be pumped up and down to raise or lower the car to a desired height.
Springs deflect as the car goes over a bump, then bounce back. The car would continue to bounce up and down if the energy stored in the springs were not dissipated in some way.
Dampers - commonly called
- perform this function. A damper has a
which moves inside a sealed, oil-filled
with the up-and-down movement of the wheel.
There are narrow control passages and one-way valves in the piston, which allow oil to flow through it from one chamber to another - but only very slowly.
This action slows down the
and returns the car to a level ride.
There are three types of damper. Telescopic dampers look like telescopes and shorten in the same way. One end is bolted to the
, the other to the body.