What are springs used for in a vehicle ?

Appearences can be deceptieve but it is the springs in a suspension system that support the vehicle weight and not the shock absorbers.This is why they are so important for the stability and balance of the vehicle.

The springs are elastic components and must be able to support large displacements and be able to regain their original shape after compression. During compression, they store energy which is then released. During the life of a vehicle, a spring will go through hundreds of thousands of compression cycles. A vehicle spring is required to regain its original form, without any deformation.

The design and manufacture of the springs is tailored to suit the particular specifications and requirements of each vehicle manufacturer, e.g. weight and cost optimisation, vehicle packaging and centre of gravity, ride comfort and handling.

This has led to a range of spring designs from the very simple to the highly complex, all made possible by Allevard Rejna Autosuspensions's extensive Research and Development work.

When a vehicle is cornering, it tends to roll towards the outside of the corner. The outboard spring is under compression whereas the inboard spring is under extension. The purpose of the stabiliser bar is to reduce the "roll" effect and to stabilise the vehicle.

The extremities of the stabiliser bar are attached to the wheels on the axle, with the central portion fixed directly to the vehicle chassis. As a result, during cornering, the right and left springs are compressed by different amounts. This creates torque in the stabiliser bar that resists the rolling effect; the extent of which is controlled by the stiffness of the bar.

An additional function of the bar is to reduce the effects of under steer and over steer whilst cornering.

As with the springs, the stabiliser bar is required to meet a wide range of vehicle manufacturer's specifications in terms of stiffness, weight, durability, noise etc. As the the stabiliser bar is often one of the last vehicle components to be specified, it is often tightly constrained by packaging requirements leading to complex geometries.

Straight stabiliser bars contribute to the torsional stiffness of semi-rigid rear axles which are required for many modern vehicles.

Torsion bars behave similarly to springs. They typically allow for large wheel displacements than springs and require less packaging space. The bars are transversal for the rear axle and longitudinal for the front axle.