Abstract: A variable displacement hydraulic pump including a control actuator configured to interact with a movable displacement control member to control the displacement of the pump; and a displacement control valve assembly configured to provide mechanical feedback control of positioning of the control actuator and thereby the displacement control member. The displacement control valve assembly includes a control valve member that is movable within a fluid flow path of the control valve assembly to control a flow of fluid to or from the control actuator. The control valve assembly includes a first valve part, a second valve part, and a biasing member configured to selectively position respective one or more portions of the first and second valve parts relative to each other to open or close a vent flow passage in response to an operating state of the pump.