HYDRAULIC WINCH SPEED CONTROL WITH PRESSURE- RESPONSIVE OVERRIDE

摘要

A system for varying the speed and displacement of a variable-displacement hydraulic motor and for providing a feedback signal which prevents the motor from stalling when an operator tries to reduce the motor displacement below the stall level. The system is especially useful for operating a hydraulic winch system on a wire rope crane. A variable displacement hydraulic pump provides pressurized fluid to operate a variable displacement hydraulic motor for lifting loads supported by the wire rope. The motor speed is controlled by varying the displacement of the pump and/or the motor, with the motor speed generally increasing as motor displacement decreases. The motor could stall if the crane operator decreases motor displacement below a critical value. A feedback signal coupled to the motor controls the motor displacement to prevent motor stalls.