HYDRAULIC DRIVE DEVICE FOR WORKING MACHINE

摘要

To enable combined operation of boom raising and arm crowding without providing a throttle and also enable arm crowding operation in the same manner as in the case where a regenerative circuit having a throttle is provided. The invention provides a hydraulic drive device for a hydraulic excavator, including: a first hydraulic pump (11) ; a first boom directional control valve (19) and a second arm directional control valve (18) which are connected in parallel to the first hydraulic pump (11); a second hydraulic pump (12); and a second boom directional control valve (22) and a first arm directional control valve (23) which are connected in parallel to the second hydraulic pump (12) ; wherein: the hydraulic drive device also includes: a third hydraulic pump (13); a third boom directional control valve (33) connected to the third hydraulic pump (13) and controlling the flow of pressure oil supplied to a boom cylinder (7); and a third arm directional control valve (34) connected in tandem with the third boom directional control valve (33) and controlling the flow of pressure oil supplied to an arm cylinder (8).