| 摘要 |
A fluid pressure powered apparatus comprises a double-acting member, a first pilot valve, a second pilot valve, and a switchable valve is disclosed. The double-acting member is operable between a first stroke end and a second stroke end by fluid pressure from th e switchable valve. The first and second pilot valves are configured to establish a biasi ng fluid pressure to first and second bias surfaces, respectively, of the switchable valve. The first and second pilot valves are actuatable by the double-acting member when at the first and seco nd stroke ends, respectively, to reduce the biasing fluid pressure on the first bias surface . In operation, the reduction of biasing fluid pressure on either the first bias surface or the second bias surface, respectively, triggers the switchable valve to switch between a first stroke position and a second stroke position, respectively. A method of reciprocating a fluid pressure powered apparatus is also disclosed.
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