Subaru 2002 Impreza Service Manual page 336

PROPORTIONING VALVE
Brakes
5. Proportioning Valve
The proportioning valve prevents the rear wheels from locking and resultant skidding that would
occur during hard braking due to transfer of vehicle weight toward the front wheels. The valve dis-
tributes a reduced pressure to the rear wheel brakes as compared with the pressure to the front
wheel brakes when a specified master cylinder fluid pressure (called "split point") is exceeded
as shown in the diagrams below.
\
: A
: B
NF0248
(1)
Master cylinder fluid pressure A: Brakes released
(2) Rear wheel cylinder fluid pressure
(3) Split point
BR-10
B: Brakes kept applied