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Independent suspension is a wide ranging expression for any car/automobile suspension system that allows each wheel on the same axle to move vertically up or down in response to a pot-hole or bump in the road independently of each other.

This contrasts with other systems such as live axle, beam axle or deDion systems whereby the wheels are fix linked i.e. movement on one side affects the wheel on the other side.

It is important to note that “independent” refers to the motion or path of movement of the wheels/suspension. It is common for the left and right sides of the suspension to be connected with anti-roll bars or other such mechanisms. The anti-roll bar ties the left and right suspension spring rates together but does not tie their motion together.

Most modern vehicles such as Audi (review Audi cars at www.stokeaudi.co.uk) have independent front and rear suspension (IFS & IRS). Fully independent suspension has an independent suspension on all wheels. Some early independent systems used swing axles, but modern systems use Chapman or MacPherson struts, trailing arms, multiple links, or wishbones.

Independent suspension in Audi cars uses several control arms to guide the wheel. They permit optimum adjustment of the desired characteristics. Double-wishbone suspension, trailing-link double wishbone suspension (LDQ axle) and trapezoidal-link rear suspension are all systems that satisfy varying demands related to vehicle dynamics, ride comfort and space requirements. A sub-frame promotes ride comfort and permits the suspension to be pre-assembled as the car is being built.

Typically, independent suspension offers a significantly better ride quality and handling characteristics, due to lower unsprung weight and the ability of each wheel to address the road undisturbed by activities of the other wheel on the vehicle. Independent suspension requires additional engineering effort and expense in development versus a live axle or beam axle arrangement. The only downside is that complex IRS solutions can also result in higher manufacturing costs. The key reason for lower unsprung weight relative to a live axle design is that, for driven wheels, the differential unit does not form part of the unsprung elements of the suspension system. Instead it is either bolted directly to the vehicle's chassis, or more commonly to a subframe. The relative movement between the wheels and the differential is achieved through the use of swinging driveshafts connected via universal (U) joints, analogous to the constant-velocity (CV) joints used in front wheel drive vehicles.