A pressure medium-actuated control device of an automated step-by-step variable speed transmission. The device having a control valve for controlling an actively engaged disconnectable type clutch which is disposed along a power flow path between a motor and a transmission input shaft, and a self-retaining valve located in the pressure supply of the clutch control valve for a rotational speed-dependent emergency actuation of the disconnectable type clutch. An electrical switch-off actuator is connected to the self-retaining valve such that the valve piston, of the self-retaining valve, can be moved into an idle position to lock the pressure supply of the clutch control valve in a powered state of the switch-off actuator, and into an operating position determined by the applied control pressures in the power-off state of the switch-off actuator.