Abstract: This hydraulic pump includes a frame, a pump shaft capable of being rotated by a thermal or electric motor, around an axis which is stationary with respect to the frame, an eccentric sleeve engaged with the pump shaft, and at least one stage of pistons arranged to be stationary with respect to the frame and radially extending in pump cylinders defining chambers. It comprises at least one tappet extending in a housing made in the eccentric sleeve and cooperating with at least one resilient means, having a resilience varying according to the load of the downstream circuit emerging at the level of the pump chambers, said tappet actuating means which decrease the piston stroke.