thumb|right|A multi-link type rear independent suspension on an [[Four-wheel drive|AWD car. The anti-roll bar has some yellow paint on it.|255x255px]]
Independent suspension is any automobile suspension system that allows each wheel on the same axle to move vertically (i.e. reacting to a bump on the road) independently of the others. This is contrasted with a beam axle or deDion axle system in which the wheels are linked. "Independent" refers to the motion or path of movement of the wheels or 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 have independent front suspension (IFS). Many vehicles also have an independent rear suspension (IRS). IRS, as the name implies, has the rear wheels independently sprung. A 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, multilink, or wishbones.
Independent suspension typically offers 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 beam or live axle arrangement. A very complex IRS solution 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 joints (U joints), analogous to the constant-velocity (CV) joints used in front-wheel-drive vehicles.
Independent suspension
Suspension
Suspension is the only component that separates the driver and/or passenger from the ground. The suspension in a vehicle helps absorb harshness in the road. There are many systems and designs that do this, such as independent suspension.
Advantages
This system provides many advantages over other suspension systems. For example, in solid axle suspension systems, when one wheel hits a bump, it affects both wheels. This will compromise traction, smoothness of the ride, and could also cause a dangerous wheel shimmy when moving at high speeds. With independent suspension systems, the bump primarily affects only the contacted wheel. This offers many advantages such as greater ride comfort, better traction, and safer, more stable vehicles on the road.
Rather than centrally mounting the transverse leaf spring and thus isolating the left and right sides of the springs, some manufacturers, starting with Fiat used two widely spaced spring mounts. This was first used on the front of the 1955 Fiat 600 and later at the rear on the Fiat 128. The spring is allowed to pivot inside of the mounts which allows the displacement of the spring on one side to affect the other side. This mechanical communication between the left and right sides of the suspension results in an effect similar to that of an anti-roll bar. Chevrolet Corvettes, starting with the 4th generation in 1984 have combined the dual pivot mounts with FRP leaf springs.
The transverse leaf spring is not used as commonly as it was earlier. It is very rare on modern cars, the Corvette and a few Volvo models being examples. In the past it was more widely used in many Triumphs. The Herald, Vitesse, Spitfire, and GT6 all used a rear transverse leaf spring, as well as the 1995-98 Volvo 960/S90/V90 and a rare Swedish sports car incorporating the Volvo 960 rear suspension called the JC Indigo.