Winch control
US4048799A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1976 |
| Grant date | Sep 20, 1977 |
| Priority date | — |
| Expiry date | Nov 17, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/20012
- WIPO fieldHandling
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.