Hydraulic circuit supply system

A supply system for supplying a hydraulic circuit with hydraulic fluid, comprising:

• a working reservoir for holding hydraulic fluid for operating the hydraulic circuit;
• an auxiliary reservoir, connected to the working reservoir via a hydraulic line, the auxiliary reservoir providing interim storage of hydraulic fluid removed from the working reservoir;
• an air pump, the air pump having an inlet connected to a suction line issuing into a fluid-free area of the auxiliary reservoir, so that relative to atmospheric ambient pressure, a negative pressure can be built up in the auxiliary reservoir, and the air pump inlet also being connected to a control line having a control opening which is covered by the hydraulic fluid in the working reservoir, at least before the air pump goes into operation;
• and
• a float valve is arranged in the suction line.