| 摘要 |
A hydraulic power steering system including a rotary control valve having an inner sleeve rotatable with the input stub shaft and a concentric outer sleeve mounted for rotation with the output worm shaft. The inner sleeve is formed on its outer periphery with axially extending equally spaced pressure and return slots associated with axially extending equally spaced slots for fluid flow switching operation. The inner sleeve has an annular recess on its inner periphery and an orifice radially extending through the inner sleeve for permitting the supply of pressure fluid into the annular recess. A piston member may be inserted between the inner sleeve and the stub shaft for rotation with the stub shaft and for sliding movement on the stub shaft. In a preferred embodiment of the invention, a plate member having thereon a projection such as a ball is provided for rotation with the outer sleeve. The piston member has a cutout adapted for receiving the projection to establish a temporary engagement between the piston member and the plate member under the fluid pressure supplied in the inner sleeve recess to urge the piston member toward the plate member.
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