HYDRAULISCHE SCHALTUNG

摘要

A hydraulic switching system for regulating the direction of travel, speed and drive moment of a hydraulic consumption unit (1), having a directional control valve (5) in the pump line (3) between a hydraulic pump (2) and the consumption unit (1), by which valve the consumption unit (1) and the pump (2) can be connected via a return circuit to a tank (7), includes a pressure relief valve assembly (6, 8) connected to the pump line (3) at a point upstream of the valve (5) and serving to connect pump line (3) to the return circuit to the tank (7). The preliminary control valve (6) of this pressure relief valve assembly is hydraulically adjusted, on a continuous scale, by means of a preliminary control unit (10) which is manually operable by an actuating lever (11), in order to control the regulating force of the valve (6) and to provide pilot control of the valve (5). Hydraulic lines connecting the control unit 10 to opposite ends of the valve (5) are also connected to the adjusting mechanism (14) of the valve (6) by means of a shuttle valve (13). <IMAGE>