Abstract: An actuation device for emergency operation of a hydraulically controlled actuator includes a housing with a fluid container connected to the actuator via a connection point and to a hydraulic supply circuit of the actuator via another connection point. A separating piston is guided lengthwise inside the fluid container via a manually operated adjusting device. The piston has a control device for a through-opening joining the connection points to each other. The actuation device provides an economical and simple way of reliably controlling and monitoring the hydraulically controlled actuator in case of malfunction by an adjustment screw screwed or unscrewed on the housing. The screwing path is chosen such that the cooperating separating piston can be displaced between two end positions. The through-opening of the separating piston has a check valve which is opened at one end position and is closed at the other.