Boom stop and back hitch compensating system
AssigneeThe Manitowoc Company, Inc.
InventorsJames G. Morrow, Sr., David J. Pech
Life of this patent
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Abstract
The back hitch assembly for a lift or tower crane includes a tension sensing device which regulates the pressure delivered to the boom stop or hold back cylinders such that as the boom hoist line and back hitch become slack when the load line is relieved more pressure is delivered to the cylinders to counteract the rearward pull on the boom or tower due to the suspended weight of the masts and equalizer assemblies.
Claims10
A boom stop compensating system for a load lifting device having a power source, a boom mounted for vertically pivoting movement, boom hoist rigging including a back hitch assembly and a boom hoist line for raising and lowering the boom and boom stop cylinder means for limiting the vertical angle to which the boom may be raised comprising, in combination, pump means for delivering fluid under pressure to the boom stop cylinder, means for sensing changes in tension in the boom hoist rigging, and regulating means interposed between said cylinders and said sensing means for increasing the fluid pressure delivered to said cylinders by said pump means as the tension in said boom hoist rigging decreases.
A boom stop compensating system as defined in clain 6 wherein said sensing means includes a penumatic regulator interposed between said source and said first section for establishing the minimum pressure signal delivered to said first section.
Dependencies are inferred from the claim text.