Rear Axle Trailing Arm Suspension

Honda CR-Z. H-shaped Torsion Beam Rear Suspension.

Honda CR-Z. H-shaped Torsion Beam Rear Suspension.

A crank axle, consists of a control arm lying longitudinally on the driving direction and mounted
to rotate on a suspension sub-frame 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 trailing-arm axle is relatively simple and is popular in 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 changes, 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 behavior under load.

The tendency to over-steer as a result of the deformation of the link (arm) when subject to
a lateral force, the roll center 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.

In the rear, an H-shaped torsion beam suspension helps free up more cabin

space. The trailing arms have been also lengthened to reduce jack-up while
cornering.

Trailing-Arm rear suspension of the Mercedes-Benz A class (1997).

In order to minimize the amount of room required, the coil spring and monotube gas-pressure shock absorber are directly supported by the chassis sub-frame. The connection tube is stress optimized oval shaped in order to withstand the high bending moments from longitudinal and lateral wheel forces which occur in the course of driving.

The torsion-bar stabilizer proceeds directly from the shock-absorber attachment for reasons of weight and ease of assembly. When establishing the spring/shock-absorber properties, the line along which the forces act and which is altered by the lift of the wheel is to be taken into consideration, as disadvantageous load-path can occur with jounce. The two sub-frames are hydraulically damped in order to achieve a good level comfort.