suspension, in automobiles, system of springs used to suspend the frame, body, engine, and power train above the wheels. Its principal purpose is to lessen the jarring of the automobile that is caused by irregularities in the roads traveled. Since the wheels of an automobile accelerate, stop, and steer it, the suspension must also serve to keep the wheels in close contact with the road surface at all times. The types of springs used in suspensions include leaf springs, coil springs, torsion bars, and air springs. There have been many refinements in modern suspensions. On most vehicles the front wheels are suspended independently, i.e., the front axle has been eliminated. Certain vehicles also have the rear wheels suspended independently. Hydraulic shock absorbers have been included to prevent the springs from shaking the automobile excessively after a jolt. An elaborate system of mechanical linkages is often included to position the mass of the vehicle accurately with respect to its wheels during accelerating, braking, and steering.