Hydraulic control circuit for controlling fan blade pitch

A hydraulic control circuit of a double-acting orientation cylinder to orient fan blades of a turbojet engine, comprising an oil tank, a variable-displacement axial piston pump including a swash plate as well as a control chamber and a compensation chamber, the tilt of the plate being controlled by pressurising these chambers, the pump being supplied by the tank and having the outlet thereof configured to be able to be connected by a supply pipe to one of the chambers of the orientation cylinder, the other chamber of the orientation cylinder being connected to the tank, the control chamber and the compensation chamber both being pressurised with a pressure corresponding to the pump outlet pressure, the control chamber and the compensation chamber-being arranged to increase the tilt of the plate in order to increase the displacement of the pump when the pressurisation pressure of these chambers increases.