Hydraulic system for working machine

A hydraulic system for a working machine, the hydraulic system comprising left and right track devices configured to be driven by separate track drive motors, a dozer device configured to be driven by a dozer cylinder, track control valves provided respectively for the left and right track devices, and for respectively controlling the track drive motors, auxiliary control valves for controlling, apart from the track drive motors and the dozer cylinder, hydraulic actuators, and two independent hydraulic-fluid discharge ports, the hydraulic system comprising:

• a pair of dozer control valves configured to be concurrently operable for controlling the dozer cylinder;
• a pilot pressure valve configured to be switchable between an independent position and a merging position,
• the independent position being a position that allows, when the left and right track devices are operated while the auxiliary control valves are not operated, hydraulic fluid from one of the hydraulic-fluid discharge ports to be independently supplied to one of the track control valves and to one of the dozer control valves, and hydraulic fluid from the other of the hydraulic-fluid discharge ports to be independently supplied to the other of the track control valves and to the other of the dozer control valves,
• the merging position being a position that allows, when at least one of the auxiliary control valves is operated, the hydraulic fluid from the one of the hydraulic-fluid discharge ports and the hydraulic fluid from the other of the hydraulic-fluid discharge ports to be merged and then supplied to the at least one of the auxiliary control valves that has been operated, and to the track control valves and the dozer control valves;
• and
• pressure compensation valves provided respectively in the control valves, and configured to distribute hydraulic fluid to the respective control valves at flow rates in accordance with extent of actuation of, irrespective of the magnitude of loads acting on, the hydraulic actuators.