| 摘要 |
A pneumatic load balancer having a hoist cylinder adapted for attachment to an overhead support such as a hook, rail, trolley or the like having a piston assembly disposed in the cylinder, a fluid chamber and a lifting cable which is wound around a dual set of pulleys with one end anchored with respect to the cylinder and the other end arranged for attachment to a load. One set of pulleys is fixed against motion near the center of the cylinder and the other set is carried by the piston assembly to reel in or to unwind the cable from the cylinder upon movement of the piston assembly by means of fluid pressure. A pneumatic control system is provided which comprises a monostat in the form a pilot pressure operated fluid pressure regulator having a built-in relief valve and which is fitted to the cylinder inlet and which can be operated either through pilot or mechanical connections to adjust the pressure of fluid available at the inlet of the cylinder in correspondence with the load carried by the cable. Valve means are also provided which are normally open to communicate the fluid chamber with atmosphere and which closes upon an increased pressure in the chamber to thereby dampen upward movement of the cable.
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