CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2017-127762, filed Jun. 29, 2017. The contents of this application are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a hydraulic system for a working machine.

DISCUSSION OF THE BACKGROUND

A technique disclosed in Japanese Unexamined Patent Application Publication No. 2016-133206 is conventionally known as a working machine having a hydraulic attachment such as a boom, an arm, a bucket, or the like.

The working machine disclosed in Japanese Unexamined Patent Application Publication No. 2016-133206 includes a first circuit to which a boom cylinder, a bucket cylinder, and a left traveling motor belong, a second circuit to which an arm cylinder, and a right traveling motor belong, a third circuit to which a swing motor belongs, a first pump serving as a hydraulic pressure source for the first circuit, a second pump serving as a hydraulic pressure source for the second circuit, and a third pump serving as a hydraulic pressure source for the third circuit, and the working machine supplies the first pump fluid to the bucket cylinder, the second pump fluid to the arm cylinder, the third pump fluid to the boom cylinder when the arm, the bucket, and the arm are operated in combination.

SUMMARY OF THE INVENTION

A hydraulic system for a working machine, includes a first hydraulic actuator to be activated by an operation fluid, a second hydraulic actuator to be activated by the operation fluid, a first pump to supply the operation fluid to the first hydraulic actuator, a second pump to supply the operation fluid to the second hydraulic actuator, a second control valve to control the operation fluid to be supplied from the second pump to the second hydraulic actuator, and a first control valve including a main control valve to control the operation fluid to be supplied from the first pump to the first hydraulic actuator, and a subordinate control valve to control the operation fluid to be supplied from the second pump to the second control valve and to the first hydraulic actuator. The operation fluid supplied from the second pump is confluent with the operation fluid to be supplied from the first pump to the first pump, in a case of activating both of the first hydraulic actuator and the second hydraulic actuator. The operation fluid supplied from the second pump is not confluent with the operation fluid to be supplied from the first pump to the first pump, in a case of inactivating at least one of the first hydraulic actuator and the second hydraulic actuator.

