Hydro-Boost at Rest
With the Hydro-Boost at rest (engine on, brakes released) oil flows from the inlet (pump) port, across the number 3 land and out the gear port. In this position, steering pressure created by the steering gear and pump is isolated from the boost cavity by the spool valve. Lands 2 and 4 block this steering pressure avoiding activation of the unit. Any leakage goes directly back to the reservoir.

For disassembled photos, see this post.

Owner caption January 2006 · Photo 1156 of 5000