L322 Range Rover System Description and Operation
BRAKES
70-34
DESCRIPTION AND OPERATION
Hand Brake
Introduction
The parking brake system utilised on the New Range Rover is a new application on Land Rover vehicles. The
characteristics of the system are significantly different to the transmission brake based system that is currently fitted
to most Land Rover vehicles.
Description
The handbrake lever is a clenched two-shell construction incorporating an automatic cable adjuster. The handbrake
cables are actuated via an equaliser and a cable centrally mounted within the lever, which is in turn attached to one
half of the spring loaded adjuster
The design of this hand brake incorporates an automatic adjuster which eliminates the need for warranty adjustments.
The two-shell design allows automatic assembly of the internal components.
The hand brake cable is centrally mounted within the lever as a significant offset of the cable causes the lever to rotate
sideways under the high cable loads required. This construction means that the part of the bracket that supports the
lever pivot must be moved outside the lever rather than having the conventional inboard position. The lever is high
mounted to suit the 'Command' driving position, on a secondary - mounting bracket, which also allows the assembly
of necessary components under the handbrake.
Function
When the lever is in the rest position, the adjuster opener holds the adjuster open. In this position, the lever is
effectively disconnected from the handbrake cable. This allows the adjuster spring, if required, to remove slack in the
handbrake cables. After less than 5 degrees of lever travel and normally before the first tooth is engaged, the adjuster
is closed and the cables and hence the parking brakes are actuated. No adjustment of the cables is required during
assembly or by the dealer. The function of the adjuster is to remove slack in the handbrake cables and not to provide
any adjustment of the parking brake itself. The adjuster spring force is always lower than the brake shoe return spring
force.
Performance
In order to achieve the required performance targets, the lever ratio is relatively high at 7.25:1. Also, in comparison to
Range Rover, fine ratchet teeth are employed for the convenience of slighter drivers. The overall performance of the
system is totally dependent on the correct adjustment and bedding of the Duo-Servo parking brake. The adjuster
travel is 25-30 mm, in other words in the worst tolerance condition the system can compensate for 25mm of slack in
the cable system. Slack in the system can be caused by both initial tolerance stack-up in the body / parking brake
system and actual 'stretch' in the system.
Replacement
The handbrake is supplied with a pin in position that locks the adjuster spring in the fully compressed condition. This
allows the handbrake to be raised to the fully up position with the cables connected, in order to facilitate the assembly
of the centre console. Subsequent to the assembly of the centre console, the pin can be removed and the lever
lowered, at which point the adjuster will provide the required cable tension.
A mounting clip is provided, which is clipped to the equaliser and fitted over the ends of the body tubes, in order to
provide location whilst the cables are fed through the body tubes and into the 'quick fit' connections in the equaliser.
This allows a 'one man' operation for cable fitment.
