Abstract: Apparatus for preventing overspeeding of an engine is provided. In preferred embodiments, an hydraulically actuable clutch is controlled by a piston-cylinder arrangement connected to a driver operable clutch pedal. The rear side of the piston in this arrangement is selectively communicated with a high pressure air source and an exhaust space by means of a solenoid valve. The solenoid valve is controlled by a tachometer switch so that the same communicates the high pressure medium to automatically actuate the disengagement of the clutch whenever a predetermined set engine speed is exceeded. The pressure medium space at the side of the piston is also communicated with a further piston-cylinder arrangement for automatically forcing an engine accelerator pedal toward a no-load engine running condition at the same time the clutch is automatically disengaged. An emergency switch is provided for overriding the clutch disengaging apparatus so as to accommodate intentional usage of the engine as a brake.