Hydraulic control circuit for controlling fan blade pitch

A hydraulic control circuit of a double-acting orientation cylinder to orient fan vanes of a turbojet engine, the hydraulic control circuit comprising:

• an oil tank,
• a variable-displacement axial piston pump including a swash plate controlled by a double-acting control and compensation cylinder comprising a control chamber and a compensation chamber,
• the double-acting orientation cylinder having a first chamber connected to the tank, the pump being supplied by the oil tank and having an outlet thereof configured to be able to be connected to a second chamber of the orientation cylinder via a supply pipe, the chambers of the control and compensation cylinder both being pressurised with a pressure corresponding to a pump outlet pressure,
• wherein the control and compensation chambers are arranged to increase a tilt of the swash plate in order to increase a displacement of the pump when pressures within each of the control and compensation chamber are increased, and wherein
• the pump has the outlet thereof connected, via the supply pipe, to a dispensing valve connected to the first and second chambers of the orientation cylinder, wherein the compensation chamber of the control and compensation cylinder is connected to the outlet of the pump, wherein the control chamber of the control and compensation cylinder is connected to the second chamber of the orientation cylinder, wherein the dispensing valve can occupy a position in which it connects, on the one hand, the supply pipe to the second chamber of the orientation cylinder, and on the other hand, the first chamber of the orientation cylinder to the tank.