| 摘要 |
A pneumatic cylinder having internal hydraulic dampening device for cushioning the motion of a pneumatic piston (44) at its end of stroke. The hydraulic device includes a pair of hydraulic pistons (50, 52) cooperating with a pair of hydraulic cylinders to form a pair of hydraulic chambers (58, 64), which communicate with each other by a restricted flow passage (74). When the pneumatic piston nears its end of stroke, one of the hydraulic pistons is moved to compress the corresponding hydraulic chamber, forcing hydraulic fluid through the restricted flow passage, to the other hydraulic chamber. The flow of hydraulic fluid through the restricted flow passage slows the pneumatic piston, thereby cushioning the end of stroke motion. The restricted flow passage can include a plurality of flow passages which are sequentially closed by pins (136, 138, 140, 142) connected to one of the hydraulic pistons, as the hydraulic piston moves, to vary the restriction in the flow passage.
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