US Patent 7480972 Actuator for a control unit

An actuator for a control unit has a control motor with a motor power takeoff shaft; a control shaft that carries the control unit; and a step-up gear, disposed between the motor power takeoff shaft and the control shaft, as well as a restoring device for restoring the control unit to a basic position if the control motor fails. To make it possible to use a single-stage step-up gear with a major step-up ratio and with advantages in terms of installation space, weight, and production costs, the restoring device has two separate energy-storing means, preferably embodied as restoring springs, of which one feeds back to the motor power takeoff shaft and the other feeds back to the control shaft.