724 / 1232
BRAKES
INTRODUCTION:
Dual circuit, diagonal split vacuum assisted hydraulic brakes
through tandem master cylinder have been provided on BOLT
and ZEST. The front brakes are ventilated disc brakes with
floating type calipers while the rear brakes are drum brakes with
self-shoe clearance (automatic) adjustment. No adjustments
are required for front & rear brakes. The parking brake is a
mechanical lever type, (cable operated) acting on rear wheels.
In addition to the conventional hydraulic brake system, an Anti-
lock Braking System (ABS) incorporating Electronic Brake
Force Distribution
(EBD) is also provided.
During a normal braking event EBD replaces the pressure
conscious regulating valve (PCRV) and limits the level of
braking force transmitted to the rear wheels. The advantage of
EBD over a PCRV is that it can moderate the braking forces at
the rear axel depending upon the load condition and available
friction at the rear wheels.
During an emergency braking event the ABS modulates the
braking force for each individual wheel. In doing so the system
optimizes the level of braking being achieved while maintaining
a stable, controllable vehicle. Where EBD only acts on the rear
wheels the ABS is able to control each wheel individually and
can facilitate pressure hold, release and increase cycles.
Both the EBD and the ABS functions work by continuously
monitoring and comparing the four individual wheel speeds and
reacting to when a wheel is detected as loosing grip with the
road surface.
The ABS is designed to be incorporated into the circuits of the
foundation brake system, and will not prevent the normal
hydraulic operation of the brakes in the event of an ABS failure.