US 4,048,799 A · Winch control

Abstract

A control for a hydraulically operated winch or the like having a hydraulically disengaged brake, a multi-speed, hydraulically controlled transmission, and a drum to be driven or braked. The control system includes means whereby the transmission is placed in neutral, automatically, whenever the brake is to be disengaged to lower a load and a control valve including a spool with small and large slots along with a drum-driven metering pump controls fast and slow lowering speeds. Emergency free fall of the load is accomplished in the valve by bypassing the small metering slot. An arrangement of an accumulator and check valves allow hydraulic disengagement of the brake even if the engine is dead and there is provided a recirculating hydraulic circuit to conserve oil in such an instance so that the accumulator volume can be minimized. A system is included whereby the accumulator may be discharged, when the prime mover is inoperative to allow the operator of the winch to leave the location with the load suspended with the knowledge that the load cannot be lowered either intentionally or accidentally.

Claims8

Dependent claims

In a control for a hydraulically operated winch or the like having a hydraulically disengaged brake, and a multispeed, hydraulically controlled transmission and a drum to be driven or braked, the combination of:

a brake control valve having an inlet, an outlet and selectively variable metering valve means between said inlet and outlet;
a metering pump adapted to be operatively associated with a winch drum so as to be driven thereby;
a first fluid conduit extending from said outlet to said metering pump;
a port in said first fluid conduit adapted to be coupled to said hydraulically disengaged brake for a winch;
a second fluid conduit extending from said metering pump to said inlet;
and
a source of fluid under pressure connected to said inlet.

4 more elements

In a control valve for a hydraulically disengaged brake or the like, the combination of:

a valve housing;
a bore in said housing;
a spool in said bore;
an inlet to said bore and adapted to be connected to a source of fluid under pressure;
a first outlet from said bore adapted to be connected to a fluid reservoir;
a second outlet from said bore adapted to be connected to a brake and being located between said inlet and said first outlet;
and
land means on said spool for alternately (a) precluding fluid flow from said inlet to said second outlet while allowing fluid flow between said outlets and in one spool position, (b) interrupting fluid flow between said outlets while allowing fluid flow from said inlet to said second outlet in another spool position;
said land means including a first, relatively long, axial groove having a relatively small cross section in its periphery and opening to the inlet side of said land means, said first groove having a progressively decreasing cross section from said inlet side;
said land means further including a second, relatively short axial groove having a relatively large cross section and opening to the inlet side of said land means;
said second groove, when allowing fluid flow from said inlet to said second outlet, serving to functionally bypass said first groove;
said spool being further shiftable within said bore so that both said first and second grooves are functionally bypassed.

9 more elements

Dependencies are inferred from the claim text.

Winch control

Life of this patent

Winch control

Life of this patent

Abstract

Claims8