| 摘要 |
A hydraulic actuator has a housing, a drive chamber in the housing, a fluid inlet into the chamber, and a piston reciprocable in the chamber. The piston has diametrical steps Exposed to fluid under pressure to cycle the piston. A sleeve is spaced from and positioned around the piston to define a return chamber. The housing has first and second seats. The first seat and a first surface of the sleeve define an exhaust valve, which has an exhaust port, for the return chamber. The exhaust port is opened and closed by reciprocating the sleeve. The second seat and a second surface of the sleeve define an inlet valve for the return chamber. Reciprocating the sleeve opens and closes the return chamber to the drive chamber. The piston and the sleeve are configured so that they interact hydraulically during cycling to generate hydraulic pressure changes in the return chamber.
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