Hydraulic system for working machine, working machine, and method of controlling working machine

A hydraulic system for a working machine, the hydraulic system comprising:

• a hydraulic pump;
• a hydraulic device to be actuated by hydraulic fluid delivered by the hydraulic pump to drive the working machine;
• a solenoid proportional valve to adjust at least one of a flow rate or a pressure of hydraulic fluid supplied from the hydraulic pump to the hydraulic device;
• and
• a controller configured or programmed to control the solenoid proportional valve;
• wherein
• the solenoid proportional valve includes a housing, a spool housed in the housing, a coil to be controlled by the controller, and a moving portion to be caused by a magnetic flux generated by the coil to move the spool;
• the housing includes a fluid chamber to store hydraulic fluid and having a volume that changes with movement of the spool;
• and
• the controller is configured or programmed to include an air-bleeding mode in which the controller controls the coil to cause the moving portion to reciprocate a plurality of times in an axial direction of the spool.