| 摘要 |
1,074,416. Shovel excavators. CESSNA AIRCRAFT CO. Feb. 10, 1966 [Aug. 2, 1965], No. 5962/66. Heading E1F. [Also in Division F1] As the piston (22, 27) of a hydraulically actuated motor operating e.g. the boom of a mechanical shovel or back hoe, Fig. 4 (not shown) approaches the end of its stroke in a cylinder (10), a slide (14) carried by the piston (22, 27) co-operates with the cylinder wall surface surrounding a side wall port (30) to progressively decrease the flow of fluid being discharged therethrough to thereby smoothly decelerate the piston. The slide is provided with an elongated groove (35) on its external surface which co-acts with the port (30) to provide a variable restriction. The groove (35) may be of constant width but gradually decreasing depth, or of gradually decreasing width but either constant on decreasing depth. Alternatively, the groove may be replaced by a series of aligned holes of gradually decreasing diameter. The slide (14) is a loose fit in the cylinder (10) and is attached to the piston by pins (17, 19) disposed in radial slots in the piston. A compression spring (20) disposed between the pin (19) and the slide urges the slide into contact with the side of the cylinder in which the port (30) is located. When the piston is to be moved in the opposite direction, pressure fluid entering the port (30) displaces the slide against the action of the spring (20) to provide a larger inlet flow passage. |
