Rear suspension (Description): Description and operation

Description

General

The rear suspension comprises two dampers, two radius arms, a Watts linkage and an anti-roll bar assembly. On vehicles without Self Levelling Suspension (SLS) coil springs are used. On vehicles with SLS air springs are used.

The anti-roll bar is an essential part of the rear suspension. On vehicles without ACE, a conventional 'passive' antiroll bar is fitted. On vehicles fitted with the ACE system, a thicker diameter anti-roll bar, known as a torsion bar, is used with an actuator at one end. FRONT SUSPENSION, DESCRIPTION AND OPERATION, Description - ACE.

The hydraulic dampers and springs provide springing for each rear wheel. The long travel dampers, springs and radius arms provide maximum axle articulation and wheel travel for off-road driving. The rear axle is controlled longitudinally by two forged steel radius arms and transversely by a Watts linkage.

Radius arms

Each radius arm is manufactured from forged steel. Two bushes are pressed into the rear of the radius arm. The rear of the radius arm is located between a fabricated bracket on the axle and secured through the bushes with two bolts and nuts. A bush is pressed into the forward end of the radius arm which is located in a fabricated bracket on each chassis longitudinal and secured through the bush with a bolt and nut. Each radius arm is similar in its construction to the front radius arms. The rear radius arms are shorter than the front and have a lug for attachment of the SLS height sensor (when fitted).

The radius arms prevent longitudinal movement of the rear axle and because of their length allow maximum axle articulation. The stiffness of the bushes in each radius arm also contributes to the vehicle roll stiffness.

Each radius arm has a notch on its lower edge which provides location for the vehicle jack.

Dampers

Two conventional telescopic dampers are used to control body/axle movement. The upper damper mounting is fitted with a bush which locates in a bracket on the chassis longitudinal. The damper is secured with a bolt which screws into a captive nut on the bracket. The lower damper mounting is also fitted with a bush and locates in a fabricated bracket attached to the rear axle. The lower mounting is secured with a bolt which screws into a captive nut on the bracket. The upper and lower bushes are replaceable items.

Air springs (vehicles with SLS)

On vehicles with SLS fitted, air springs are fitted between the rear axle and the chassis. Each spring is located at its base on a fabricated platform on the rear axle. The top of the spring locates in a fabricated bracket attached to the outside of each chassis longitudinal.

The plastic base of the air spring has two lugs which locate in a slotted hole in the rear axle platform. The spring is secured by rotating the spring through 90°, locating the lug in the platform. The plastic top of the air spring has two grooved pins which locate in holes in the bracket on the chassis. Two spring clips locate on the grooved pins and retain the top of the spring in position.

Each air spring comprises a top plate assembly, an air bag and a base piston. The air bag is attached to the top plate and the piston with a crimped ring. The air bag is made from a flexible rubber material which allows the bag to expand with air pressure and deform under load. The top plate assembly comprises the plastic top plate with two bonded grooved pins on its top face. In the centre of the top face is a female connector which allows for the attachment of the air hose from the SLS compressor. The piston is made from plastic and is shaped to allow the air bag to roll over its outer diameter. The base of the piston is recessed with a boss moulded in the centre. The boss has two lugs which provide attachment to the axle platform.