| 摘要 |
A piston head has opposite fluid drive surfaces and is enclosed in a cylinder housing also having opposite fluid drive surfaces. The piston head is secured to a piston rod anchored at one end to a stationary support whereby the piston head and cylinder housing produce driving movement of the cylinder housing. The cylinder housing has a work engaging arm on the exterior thereof. Fluid supply conduits lead into the piston head and open between the fluid drive surfaces. Control valves are provided between a pressured fluid supply and the piston head and include cycling controls providing advancing and retracting movement of the cylinder housing for reciprocating operation of the work engaging arm. A cycling operation is initiated by a normally closed spring return operating valve. |
