US 4,552,339 A · Hoisting device with compensated tackle

Abstract

A hydraulic or pneumatic cylinder supports a pair of non-circular discs and a circular pulley about which a hoisting cable and a carrying cable are trained. The discs are configured such that a constant force is exerted on a load supported by the hoisting cable independent of the variation in pressure in the cylinder due to displacement of the piston supporting the discs. The carrying cable comprises two runs; one having one end fixed to one of the discs and the other end fixed to the supporting base, and the other having one end fixed to the other disc and the other end fixed to a pulley block supporting the load. The hoisting cable extends from a winch, over the circular pulley, to the pulley block. The arrangement compensates for relative motion between the load and the supporting base.

Claims14

Dependent claims

A hoisting device arranged on a movable support, carrying cable means attached to the support, a tackle suspended from said carrying cable means and including means for attaching a load thereto, at least one hoisting cable connected with said tackle for raising and lowering a load, and motion compensating means for causing said load to remain in a fixed position when said movable support moves relative to said fixed position, said motion compensating means including a control pressure source, and pressure actuated means connected to said control pressure source said pressure actuated means being extendable and retractable in response to variation of said control pressure;

said motion compensating means also including first means and second means which are engaged by said carrying cable means and shifted by said pressure actuated means for simultaneously reeling in and paying out said carrying cable means to impart varying load-related forces on said pressure actuated means.

A hoisting device for suspending a load from a floating hull subjected to vertical wave motion, comprising the combination of:

a tackle assembly comprising an upper block having at least one pulley and a lower block having at least two pulleys and provided with load supporting means;
a winch on said hull and a hoisting cable wound thereon, said hoisting cable being passed over one of said two pulleys of said lower block, over said one pulley of said upper block, over the other of said two pulleys of said lower block and then into connection with said upper block;
carrying cable means for suspending said upper block from said hull;
and
motion compensating means for simultaneously reeling in and paying out said carrying cable means to maintain said lower block at a substantially fixed vertical position despite vertical motion imparted to said hull, said motion compensating means comprising pressure actuated means which is expandable and retractable to reel in and pay out said carrying cable means while its actuating pressure varies in response to expansion and contraction, and means responsive to expansion and contraction of said pressure actuated means for varying the resistance to expansion and contraction thereof in consonance with variation of said actuating pressure.

2 more elements

Dependencies are inferred from the claim text.

Hoisting device with compensated tackle

Life of this patent

Hoisting device with compensated tackle

Life of this patent

Abstract

Claims14