Abstract: The invention relates to a power steering assembly for a hydraulic power steering system of motor vehicles, comprising at least one hydraulic servo valve with a control member (3) for controlling the steering assistance in accordance with a relative rotation of an input shaft with respect to an output shaft (2), and at least one actuator (9) for the relative adjustment of the control member (3) with respect to the input shaft or output shaft (2) in order to influence the steering assistance characteristic. Further, the power steering assembly comprises a summation gearing having a first rotatable drive member (4) that is in operative engagement with the control member (3), and a second rotatable drive member (5) that is in operative engagement with an output element (8) of the actuator (9), and an output member (6).