Abstract: A flowmeter for determining the amount of flowing medium using an orifice (4) and a resistor body (5) in a cavity (6) through which the medium to be measured flows. Not the resistor body (5) but an orifice sleeve (4) is displaced as a consequence of the varying primary pressure and thus the degree of opening of the flow orifice is determined depending on the amount of flow of the flowing medium. A satisfactory linearization of the subregion of the function .DELTA.p (V) is obtained.

Abstract: For emergency operation of an automatic friction clutch (3) of a truck which is operated during normal running by an electronic controller (9) via an electric motor driven actuator (11) and a hydraulic system (19, 21, 23), it is proposed that the clutch be controlled manually via a compressed air actuator (29), in particular via a compressed air servo actuator, by means of a changeover valve (39) which connects the compressed air actuator (29) alternately to a compressed air source (37) or via a flow throttle (41) to the atmosphere.

Abstract: The control device for a motor-vehicle friction clutch incorporates an electric motor which drives an output member in a substantially translational motion through a motion conversion crank gear unit designed as a worm gearing. This axis of a worm of the crank gear unit and the resultant drive force exerted on the output member by the assigned worm gearwheel lie in a common plane normal to the axis of rotation of the worm gearwheel. A spring-type energy accumulator supports the drive motion of the electric motor in the release direction of the clutch and is tensioned in the engagement direction by the electric motor. In this way a comparatively small-sized electric motor can also be used for rapid release movements.