Abstract: A redundant steering mechanism for a craft, especially an aircraft, comprs redundant control components which become effective when the normal steering components become disabled as a result of an electrical power supply failure. The redundant control components do not affect the normal control system but are effective even if the electrical power supply of the craft should fail. The redundant control components are operated by a hydraulic or pneumatic medium acting as a signal carrier. The control signal is a multicomponent signal, one component of which is derived from the pilot's control stick and other signal components are derived from such factors as the speed, the angle of attack and so forth. These signal components are superimposed to form the mechanical emergency control signal for operating a hydraulic or pneumatic steering element.

Abstract: The present servomotor has a working piston in a piston cylinder. The worg piston is connected to a spindle having a relatively high pitch. The spindle is attached at one end thereof to a control disk system comprising three control disks. The two outer control disks are rigidly connected to the spindle, and the central control disk is connected to a digital stepping motor. The central disk is arranged between the two outer control disks so that the central disk may rotate substantially free of play, whereby the rated position of a stepping drive motor corresponds precisely to the actual position of a linear output member, such as a piston rod.