A turbine valve actuator (100) controls a valve unit of a media-operated consumer unit, such as a steam or gas turbine, and has an actuating part drive (102) with a movable actuating part (104), a first media space (106) and a second media space (108). A pressure build up in the first media space (106) attempts to cause a movement of the actuating part (104) in a first direction (R). A pressure build-up in the second media space (108) attempts to cause a movement of the actuating part (104) in an opposing second direction (GR). The first media space (106) can be supplied with a fluid in predeterminable amounts by a supply (110). The second media space (108) is acted upon by a hydraulic accumulator (112) provided with a preload pressure and permanently connected to the second media space (108).