| Fig. 1: Schematic of hill holder assembly on manual transaxle
equipped models
|
A feature unique to Subaru, the hill holder is a system designed to engage a single brake channel when a manual transaxle vehicle is stopped on an uphill. The system, in effect, holds the vehicle, to enable ease of starting on an uphill.
The system consists of the basic brake system components and the addition of the Pressure Hold Valve (PHV). The pressure hold valve is connected to one of the service brake pipes. When the clutch pedal is depressed on an uphill, the pushrod in the PHV is pushed in and/or pulled out by the camshaft that is interlinked with the clutch pedal to change the clearance between the PHV ball and the seal. This opens or closes the hydraulic system to the brakes.
The operation of the system is fairly simple; when the car is stopped on an uphill, and the clutch is pressed along with the brake pedal (as in any normal stop), the cam mechanism in the PHV moves the ball valve. This, in effect, applies one side of the brake system and your foot can be taken off of the brake pedal and moved to the gas pedal. As you begin to move the vehicle and release the clutch, the brake system is then also released and you can begin moving ahead. This all has the same effect as stopping on a hill and putting the parking brake on, to make taking off easier.
The hill holder feature is standard on all manual shift models of Subaru from 1985–92, except for the Justy.
