hydraulic drive system for hydraulic work vehicle

摘要

A hydraulic drive system is provided with a signal guide system for guiding a delivery pressure of a pump (21) as a command pressure via a line (28) and a port (29), another signal guide system for guiding a pilot pressure of a pilot pump (22) as another command pressure via a line (30) and a port (31), a tilting control unit (23) for controlling the displacement of the pump (21) by the command pressures guided to the ports (29,31), a controller (33) having a command current-setting unit (34) for setting a relationship between a target engine speed and a command current, a target engine speed-indicating unit (35) for an engine (20), and a solenoid-operated proportional valve (32) for allowing the pilot pressure of the line (30) to pass as is while no drive signal is outputted from the controller (33) but for being reduced in opening to change the pilot pressure to a smaller value when a drive signal is outputted from the controller (33). <IMAGE>