An actuator for moving a first component relative to a second component includes a first actuating mechanism secured to the first component and having a first motor, a first nut, and a first shaft secured to the first motor and the first nut such that the first nut is rotatable with the first motor. A second actuating mechanism is secured to the second component and has a second motor, a second nut, and a second shaft secured to the second motor and the second nut such that the second nut is rotatable with the second motor. A screw is threadably engaged with the first nut and the second nut such that rotation of at least one of the first motor and the second motor causes movement between the first and second nuts to move the second component relative to the first component.

A drive device serves for adjusting an operating element for a valve, a throttle, a blow-out preventor or the like, in particular in the field of gas and oil production, the operating element being actively connected to at least one driving motor via a drive train, and at least one transmission changing unit being arranged in the drive train for converting a revolution of the driving motor into a revolution of the operating element and/or a revolution/linear motion converter being arranged for converting the revolution of the driving motor into a linear motion of the operating element. In order to also have a very compact design in case of a high possible performance and to simultaneously permit a good thermal distribution within the drive device, so that separate cooling devices for carrying off the generated lost heat are superfluous, the drive train comprises at least one essentially disk- or wheel-shaped revolution introducing device which is actively connected with at least two drive shafts driven by separate driving motors.

A subsea electric actuator includes an electric motor and a telescopic drive connection from the motor to a drive unit that can be moved to and fro and converts rotary motion of the connection to linear motion of an actuating stem. A return spring is operable on the drive unit to urge the actuating stem towards a datum state. An electromagnetic latch is operative when set to maintain the drive unit in a predetermined position so as to decouple the action of the return spring whereby the stem can be advanced and retracted relative to the drive unit free from the action of the return spring. De-energization of the latch allows the return spring to operate on the drive unit to return the actuating stem to the datum state. Various forms of electromagnetic latches are described.