Impreza Coupe FWD F4-1820cc 1.8L SOHC (1995)
Fig. 19 Hill Holder Deactivated
The Hill holder is essentially a Pressure Hold Valve (PHV), Fig. 16, built into one brake circuit, that maintains hydraulic pressure in the brake
circuit when the vehicle is facing uphill and the clutch pedal is depressed, Fig. 17.
The PHV lever, Fig. 16, is connected through a linkage to the clutch pedal and controlled by a camshaft which provides the motion to the PHV
driveshaft. The PHV driveshaft controls the clearance between the PHV inertia controlled ball and seal.
When the clutch pedal is depressed, the PHV driveshaft is pulled into the seal, allowing the ball free movement. If the vehicle is facing uphill,
inertia will cause the ball to roll onto the seal, Fig. 18, thereby holding hydraulic pressure. When the clutch is released, Fig. 19, the driveshaft is
forced into the ball chamber, unsealing the ball and releasing hydraulic pressure.
