rear axle trailing arm suspension – also known as a crank axle – consists of a control arm lying longitudinally in the driving direction and mounted to rotate on a suspension subframe or on the body on both sides of the vehicle . The control arm has to withstand forces in all directions, and is therefore highly subject to bending and torsional stress ). Moreover, no camber and toe-in changes are caused by vertical and lateral forces.
The rear axle trailing arm suspension is relatively simple and is popular on front-wheel drive vehicles. It offers the advantage that the car body floor pan can be flat and the fuel tank and/or spare wheel can be positioned between the suspension control arms. If the pivot axes lie parallel to the floor, the bump and rebound-travel wheels undergo no track width, camber or toe-in change, and the wheel base simply shortens slightly. If torsion springs are applied, the length of the control arm can be used to influence the progressivity of the springing to achieve better vibration behaviour under load. The control arm pivots also provide the radius-arm axis O; i.e. during braking the tail end is drawn down at this point.
The tendency to oversteer as a result of the deformation of the link (arm) when subject to a lateral force, the roll centre at floor level the extremely small possibility of a kinematic and elastokinematic effect on the position of the wheels and the inclination of the wheels during cornering consistent with the inclination of the body outwards (unwanted positive camber) are disadvantages.
On rear axle trailing-link suspensions, the vertical force FZ,W together with the lateral forces FY,W cause bending and torsional stress, making a corresponding (hollow) profile, e.g. a closed box profile necessary.