W 250 Pickup V8-360 5.9L VIN I (1987)
Hydraulic Brake Booster: Description and Operation
Hydro-Boost II
Hydro-Boost II is an hydraulically operated power brake booster. The hydraulic brake booster consists of an open center spool valve and an hydraulic
cylinder combined into a single housing. The power steering pump provides the hydraulic fluid pressure to operate both the power brake booster and the
power steering gear.
A dual master cylinder is bolted to the brake booster and is operated by a pushrod projecting from the booster cylinder bore.
The Hydro-Boost II also has an accumulator system which stores sufficient fluid under pressure to provide one power assisted brake application when
steering pump failure occurs.