US Patent 10316493 Hydraulic system and working machine including the same

A hydraulic system includes a hydraulic pump to discharge an operation fluid, a hydraulic device to be operated by the operation fluid, a plurality of hydraulic pressure controllers each to change an operation state of the hydraulic pressure controller based on a pressure of the operation fluid so as to control the hydraulic device, and a proportional valve connected to the plurality of hydraulic pressure controllers. The proportional valve is configured to set a pressure of the operation fluid supplied to the hydraulic pressure controllers.