Hydraulic motor seal and valve arrangement

摘要

The hydraulic brake booster power piston has a rectangular cross section seal groove containing a rectangular cross section lathe cut seal having a greater inner diameter than the groove as well as a greater outer diameter. Radial clearance is provided between the piston and the cylinder wall. The groove has one or more holes at its inner diameter opening axially into the booster power pressure chamber. The seal is also axially thinner than the groove. Power pressure holds the seal in sealing relation with the cylinder wall and the piston. When fluid must flow from the exhaust chamber side of the piston to the power chamber side (e.g. during manual no-power operation) the seal moves to the other groove side, allowing flow radially inward in the groove and past the seal inner periphery through the hole or holes to the power chamber.