Apparatus for operating a load-controlled hydraulic supply of an agricultural tractor

An agricultural tractor having an apparatus for operating a load-controlled hydraulic supply, comprising:

• a hydraulic pump which is adjustable with respect to a displacement volume for supplying pressurized hydraulic fluid;
• an actuator to adjust a pump swivel angle of the hydraulic pump;
• a swivel angle sensor to detect the pump swivel angle;
• a proportional valve having an electrical actuator;
• a primary hydraulic consumer to carry out a superordinate hydraulic function and to be directly connected to a conveying outlet of the hydraulic pump;
• a secondary hydraulic consumer to carry out a subordinate hydraulic function and to be connected to the conveying outlet of the hydraulic pump via the proportional valve;
• a first pressure sensor to detect a system pressure at the conveying outlet of the hydraulic pump;
• a second pressure sensor to detect a load pressure of the primary hydraulic consumer;
• a third pressure sensor to detect a load pressure of the secondary hydraulic consumer;
• and
• a control unit, including a processer and memory, configured to:
• communicate with the actuator, the swivel angle sensor, the electrical actuator, the first pressure sensor, the second pressure sensor, and the third pressure sensor,
• conclude a required power exceeds a conveying capacity of the hydraulic pump when the control unit recognizes the hydraulic pump is in an operating state indicating a maximum displacement volume by evaluating the pump swivel angle detected via the swivel angle sensor and the control unit recognizes a pressure difference between the system pressure detected via the first pressure sensor and a highest reported load pressure of the primary and secondary hydraulic consumers detected via the second and third pressure sensors falls below an admissible pressure difference, and
• move the proportional valve into a closed valve position via the electrical actuator electrically actuated by the control unit when the control unit concludes the required power exceeds the conveying capacity of the hydraulic pump.