Abstract: An electric motor actuating drive for actuating elements designed such that the drive train, which is formed from spur gears, is not self-locking, and such that a braking spring is operatively connected to a gearbox stage upstream of the output-drive element of the drive train, such that, when the drive motor is disconnected, the actuating element is effectively prevented from being moved even when attempts are made to move it by external force or by extreme force. Furthermore, the actuating drive is in the form of a spring return and is equipped with a drive spring which is arranged such that the load on it is removed in the event of electrical power failure, and it therefore acts as a drive element. Furthermore, the electrical components are arranged in an end-face housing wall for a compact design.

Abstract: An electromotive servo drive includes a drive motor, a drive train, which is fitted with an output member and includes at least one gear stage for reducing the rotation speed of the motor, and a rotatable hand-operated adjusting shaft for adjusting the output member of the drive train such that at least the drive train, arranged between the adjusting shaft and the output member, is self-locking. One of the gear stages is fitted with a brake element such that the part of the drive train leading from the gear stage to the output member is prevented from returning, while the hand-operated adjusting shaft can freely rotate in both directions of rotation. The brake element is a wrap spring which is rotatably supported in a bushing, and an inner control part engages the wrap spring to couple both angled ends of the wrap spring such that the wrap spring can be expanded in order to obtain a braking effect in a rotation direction.