Hydraulic drive apparatus for e.g. excavator, has control unit to control piston chambers of cylinder-piston units via control of switching valves based on measurement result of pressure sensors

摘要

The apparatus has piston chambers (2a-2c) that are associated with electrically-controlled switching valve (V1- V3). The respective output (V1A-V3A) of piston chamber is selectively connected to one of hydraulic outputs (pA,pB) of associated proportional valve (5). The pressure sensors (8,9) are provided to measure the pressure in the respective two hydraulic outputs of proportional valves. A control unit (6) is provided to control piston chambers of cylinder-piston units (2) via control of the switching valves based on measurement result of pressure sensors.