Springs and dampers the dynamic elements of suspension

Springs and dampers prevent the shocks from the wheels of a vehicle to be transmitted to its body. So what is it that we want when we go about looking for the best combination of these dynamic elements of a vehicle?

A spring must be be resilient, that is to say, it must be able to absorb energy when it is compressed and then must also be able to release energy when it expands. While doing so the spring must not become permanently deformed.

It must also be compact and ideally be able to serve as a suspension linkage as well.

The spring rate should increase as we compress it. Here the spring rate is the amount of load required to compress the spring through a unit deflection. So an increasing spring rate would mean that the load required to compress the spring increases as it gets compressed.

In a vehicle the spring experiences repetitive stressing. So it must be able to sustain the fatigue this causes and not fail under such loading.

In Armored Fighting Vehicles (AFVs) the spring must not be vulnerable.

Finally having as spring which gives variable height could be advantages in  AFVs.

Dampers form the other part of the dynamic elements of a suspension.

These must like springs be compact, robust and should be able to act partially as a suspension linkage.

In addition to these they should have the ability to compress softly but rebound quickly. Also dampers should have the ability of working well even under a high frequency of compression and release.

All this movement of the suspension will produce considerable heat in the dampers. They should be able to dissipate this heat well.

An ideal combination of springs and dampers is to be designed for every vehicle. This is vital for comfort of the crew of a vehicle and for the proper functioning of the more delicate of the systems mounted inside and AFV

Why do we need a suspension in a vehicle?

Simply stated, we need a suspension in vehicles, to ensure that the we get a smooth ride and to allow the vehicle to be handled properly.

A supermarket trolley does rattle a lot when we take it to the parking lot on a surface rougher than the store flooring. The vibrations received from the ground are directly transmitted to the basket of the trolley as the wheels are mounted on the basket structure without any suspension.

A vehicle without a suspension would find itself in a similar situation. Riding in such a vehicle would be very uncomfortable.

Engineers while designing a vehicle's suspension focus on making the ride and handling of the vehicle as comfortable as possible. They do this for a variety of ground surfaces and for a range of vehicle speeds.

So suspension design aims to do two main things:

First is to insulate the occupants of the vehicle from shocks and vibrations transmitted from the ground to the wheels.

Second to ensure that the wheels of the vehicle stay in contact with the ground and to enable the control and steering of the vehicle.

These two aims are achieved by having springs and dampers, these being the dynamic elements of suspension, and linkages from the vehicle body to the wheels, which are the kinematic elements of suspension.

The way in which we design and construct the dynamic and kinematic element of suspension shape the ride and handling characteristics of vehicles.