Flexible pump assembly for use in a fan drive

A pump assembly comprising:

• a first working port;
• a second working port configured to be fluidically connected to at least one hydraulic motor in a closed hydraulic circuit;
• a drive shaft configured such that, in a full revolution of the drive shaft, a displacement volume of pressurized fluid is conveyed between the first and second working ports;
• a double-acting control cylinder via which the displacement volume is continuously adjustable, the double-acting control cylinder having a first control chamber and a second control chamber assigned, respectively, to a first receiving bore and a second receiving bore, which are permanently fluidically connected to the respective first and second control chambers, the first and second receiving bores each being of a common design and each being configured to receive a built-in valve;
• a first pressure sensor configured to measure a first actual pressure at the first working port;
• a second pressure sensor configured to measure a second actual pressure at the second working port;
• an electrically adjustable pressure control valve installed in a first one of the first and second receiving bores;
• an electrically adjustable 3/2-way switching valve installed in the other of the first and second receiving bores;
• and
• a control device to which the first and second pressure sensors, the pressure control valve, and the 3/2-way switching valve are connected, the control device being configured to:
• receive a target conveying pressure difference;
• and
• control the pressure control valve and the 3/2-way switching valve to adjust the displacement volume in such a way that a difference between the first and second actual pressures approaches the target conveying pressure difference.