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5 - 58
BRAKES
When captured fluid pressure i s high, the control
module opens the dump valve (Fig. 7). Since the
dump valve is connected to the accumulator, a por-
tion of the captured fluid is diverted through the
valve and into the accumulator. The amount of fluid
diverted i s sufficient to reduce apply pressure to anti-
lock levels.
When rear brake pressure requirements return to
normal levels, the accumulator spring closes the ac-
cumulator. Fluid i n the accumulator is forced out
and back into the hydraulic system.
ACCUMULATOR
OPEN
•mini]
• r v i i f f t i l
DUMP
VALVE
ISOLATION
VALVE
CLOSED
FROM
MASTER
CYLINDER
Isolation/Dump Valve Cycle Times
Activation (opening/closing) of the isolation and
dump valves is continous during anti-lock operation.
The valves cycle rapidly i n response to speed sensor
inputs and control module signal commands. Cycle
times are measured i n milliseconds.
A s the demand for anti-lock mode brake operation
is decreased, the module deactivates the hydraulic
valve components to restore normal brake operation.
FROM REAR BRAKES TO ACCUMULATOR
J9005-95
Fig. 7 Dump Valve And Accumulator Position In
Pressure Relief Mode
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