HYDRAULIC DRIVING UNIT FOR CONSTRUCTION MACHINERY

摘要

This invention relates to a hydraulic driving unit provided with: an engine (1); a variable capacity hydraulic pump (2) driven by said engine; at least one hydraulic actuator driven by oil delivered from the pump (6); a control valve means (8) for interconnecting the hydraulic pump and actuator and controlling the flow rate of hydraulic fluid fed to the actuator according to the degree of operation of an operating means (58); a pump control means (17) for controlling the displacement volume of the hydraulic pump according to the degree of operation of the operating means so that the discharge quantity of the hydraulic pump increases as the aforesaid degree of operation increases; and an engine control means (29) for controlling the RPM of the engine. The engine control means (29) monitors whether or not the discharge quantity of the hydraulic pump (2) reaches saturation and, when a specified saturation condition is reached by hydraulic pump, it can exhibit such functions (33, 36) as increasing the RPM of the engine (1) and eliminating saturation.