Hydraulic system

A hydraulic system, comprising:

• a variable displacement hydraulic pump;
• a control valve configured to control a supply state of a hydraulic fluid from the hydraulic pump to a hydraulic actuator;
• a sensing oil passage configured to extract a pilot hydraulic fluid portion branching from the hydraulic fluid being supplied from the control valve to the hydraulic actuator;
• a pump operating unit configured to control a discharge amount of the hydraulic pump to an increase side in response to increasing of a pressure of the pilot hydraulic fluid portion in the sensing oil passage and to control the discharge amount of the hydraulic pump to a decrease side in response to decreasing of the pressure of the pilot hydraulic fluid portion in the sensing oil passage;
• and
• an operating valve provided in the sensing oil passage, and
• wherein:
• the operating valve is switchable between an open state allowing the sensing oil passage to be open and a closed state blocking the pilot hydraulic fluid portion from flowing toward the control valve in the sensing oil passage,
• the operating valve is maintained in the open state while an operation pressure is less than a setting pressure, and the operation pressure is a pressure of the pilot hydraulic fluid portion in a portion of the sensing oil passage which portion is between the operating valve and the control valve, and
• the operating valve is switched to the closed state in response to increasing of the operation pressure to the setting pressure or more.