Abstract: A hydraulically-actuated controller is disclosed for controlling delivery of hydraulic fluid from a variable-displacement, pressure-compensated pump to a hydraulically-powered reel on which is wound a cable or other flexible member extending from the reel to a tie point. Rotation of the reel is controlled appropriately to maintain the cable tautly between the reel and tie point as the distance therebetween changes. One use is on an electrically-powered mining vehicle, the power cable of which extends from a fixed power source to the vehicle-mounted reel. The controller is in a pay-in-mode whenever the distance between the reel and tie point is decreasing or remaining constant, and in a pay-out mode whenever said distance is increasing. During pay-in, pressurized hydraulic fluid is directed from the pump to the reel motor. During pay-out, pump output is occluded and fluid is directed through a restriction from the reel motor to the reservoir, the restriction serving to brake motor rotation.

Abstract: An all-hydraulic brake release system is disclosed for use on a vehicle having a transmission fluid pressure source, a brake fluid pressure source and a spring-applied, fluid pressure-released vehicle brake. The system has a control valve block which is hydraulically connected to the transmission fluid pressure source, the brake fluid pressure source and the brake. A first, transmission clutch pressure-responsive valve in the block controls the fluid connection between the brake fluid pressure source and the vehicle brake. A second, brake fluid pressure-responsive valve in the block controls the communication of brake fluid pressure to a pilot end of the first valve. If either brake fluid pressure or transmission clutch pressure falls below respective predetermined values, the first valve closes to cut off the supply of brake fluid pressure to the brake such that the brake is applied to stop vehicle movement.