Crown block compensator

Abstract

Disclosed is a compensator applicable for use with a traveling block supported from a mast, derrick or the like by means of a crown block wherein the traveling block may be utilized for supporting objects. Two fluid pressure piston-and-cylinder assemblies are arrayed on opposite sides of a line of travel of the traveling block relative to the crown block so that a flexible line positioned about the sheaves of both blocks passes over a pulley supported by one fluid pressure assembly to one side of the line of travel and, on the other side, the flexible line passes over a pulley supported by the other fluid pressure assembly. One end of the flexible line may be anchored relative to the mast as a deadline while the line at its other end may be selectively retracted or payed out by a drawworks or the like fixed relative to the mast. In one embodiment, the pulleys are carried by a carriage which is carried by the fluid pressure assemblies. The crown block is supported by flexible lines passing over pulleys also supported by the fluid pressure assemblies. In another embodiment, the fluid pressure assemblies directly support the crown block, and pulley assemblies are supported by flexible lines between the crown block and the mast, and include pulleys over which the flexible line connecting the two blocks passes. With the drawworks holding the first flexible line fixed, the crown block and the traveling block may move in unison relative to the mast with proportional reciprocable movement on behalf of each of the fluid pressure assemblies while the traveling block remains stationary relative to the crown block. Operation of the drawworks to retract or pay out the line results in manipulation of the traveling block relative to the crown block regardless of movement of the two blocks relative to the mast.