A linear actuator, preferably for sickbeds and beds for domestic use, comprises a reversible electric motor (2) which, via a reduction gear, drives a spindle (4) with a nut (5) secured against rotation so that an activating element (6) connected with the nut is moved to and fro in response to the direction of rotation of the motor. In an emergency, the actuator may be driven manually with a hand crank, as a rear attachment, with which the actuator is secured, has a longitudinal opening in the longitudinal axis of the spindle, whereby the hand crank may be caused to engage the spindle. For this purpose, a shaft member is mounted in the rear attachment, said shaft member being engaged with the spindle and protruding rearwards from the rear attachment with one end. Control of the motor typically takes place via an H-bridge so that the motor does not short-circuit when the actuator is operated manually, it is ensured that the motor is not self-locking when the actuator is operated manually.
