Pulse controlled linear actuator comprising a working cylinder (9) for receiving a medium introduced through a valve system by a compressor/pump, a piston, the shank (13) of which represents the output of the actuator. It also comprises a central solenoid (1) and alternately moved iron cores (3). The central solenoid (1) and the iron cores (3) are arranged between upper and lower solenoids (2). The iron cores (3) have two separate medium spaces (14, 15). The first medium space (14) leads into the portion of the working cylinder (9) above the piston (10) and under the piston (10). The second medium space (15) is separated from the space between the iron cores (3) by the iron cores (3) and leads into the portion of the working cylinder (9) above the piston (10) and under the piston (10). The valves (4, 8) are counter-phase or phase pulse controlled.

An actuating drive for a control valve contains a working cylinder which has a piston and a piston rod and forms an actuator for the control valve. The piston bounds a first pressure space and a second pressure space to displace the piston counter to the force of a spring by applying pressure to the first pressure space via a working medium. A working medium circuit is connected to the working cylinder at first and second pressure connections to introduce and evacuate the working medium into/from the first and second pressure spaces. The working medium circuit has a working medium pump connected to convey the working fluid, at a pressure side, to the first pressure connection, and at a suction side, to the second pressure connection. The first pressure space is permanently connected, so as to convey working fluid, to the second pressure space via a bypass line.

An actuating drive for a control valve contains a working cylinder which has a piston and a piston rod and forms an actuator for the control valve. The piston bounds a first pressure space and a second pressure space to displace the piston counter to the force of a spring by applying pressure to the first pressure space via a working medium. A working medium circuit is connected to the working cylinder at first and second pressure connections to introduce and evacuate the working medium into/from the first and second pressure spaces. The working medium circuit has a working medium pump connected to convey the working fluid, at a pressure side, to the first pressure connection, and at a suction side, to the second pressure connection. The first pressure space is permanently connected, so as to convey working fluid, to the second pressure space via a bypass line.