Control device for the speed control of pneumatic and/or hydraulic working pistons

A control device for the speed control of pneumatic and/or hydraulic power pistons and machine elements driven by such power pistons, wherein the control of the power piston speed is effected across at least part of the path of movement of said machine element by the pressure head existing in a liquid flowing in parallel with the movement of operation or sroke of said machine element, said pressure head being produced by throttling means defining throttling orifices or apertures adapted to be set to a constant size or adapted to be varied in accordance with the position of said power piston, characterized in that the first liquid flow is utilized as a signal carrier or transmitter for varying the degree of opening of said throttle orifices (36 or 37), wherein a liquid volume and pressure tranducer (3) having an incrementally variable transmission ratio is interposed between said throttling means (2) and said signal transmitter, and that said throttling means which is equipped with a plurality of differently shaped orifice cross-sections adapted to be selectively placed into action, controls the pressure head of a second oil circuit, said pressure head being adapted to be converted into mechanical power through a piston securely connected to the power piston rod or through the power piston per se.