| 摘要 |
A double acting telescopic hydraulic cylinder comprises a hollow base member arranged to be supported pivotally and including a removably end closure at its inner end. The interior surface of the base member incorporates a set of machined grooves which removably mount a set of rings that act as a stop, a fluid seal, a bearing and a wiper for the largest of a plurality of telescoping cylinder stages each incorporating a similar set of internal machined grooves and rings which cooperate with the adjacent smaller stage. The smallest telescopic cylinder stage receives a hollow telescopic piston stage closed at its inner and outer ends. An internal groove on the inner end of each telescoping cylinder stage removably mounts a lifting ring for engaging the next smaller stage. An external groove on the inner end of each stage removably mounts a guide bearing ring for cooperation at its forward end with the stop ring of the adjacent larger stage. A retraction fluid pressure port communicates with a cavity in the interior of the piston stage. A piston ring on the inner end of one or more of the stages is arranged for sealing engagement with the inside surface of the next larger stage, and a fluid pressure passageway communicates the piston stage cavity with the outer side of each piston ring. An extension fluid pressure port is arranged to apply extension fluid pressure to the inner side of each piston ring.
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