The suspension system has multiple purposes. First of all it is responsible for constantly keeping the wheels in contact with the road surface during all situations, ensuring handling and stability. It is also the part of the vehicle responsible for isolating the passengers from road shocks and maintaining a balance between safety and a comfortable ride. Components of the suspension system may include, control arms, bushings, torsion bars, spring coils, dumpers, leaf springs (in older vehicles), anti roll bars, ball joints and air springs (in case of more modern air suspension systems).
Linkages and joints of the suspension system may be worn and require replacement. Bushings also get worn often. Dumpers will fail through time (the first sign of this is usually oil leak). Other suspension parts may bend or brake due to collisions or intense driving