US Patent 7121126 Apparatus for locking a motor-vehicle steering shaft

A locking bolt for irrotationally locking a motor-vehicle steering shaft is axially movable inside a housing between locked and release positions, and is fixable in the locked position by means of a spring-loaded securing pin axially movable in the housing that cooperates with a lateral recess in the bolt. The bolt is fixed in the event a part of the housing fitted with a retaining arm retaining the securing pin against the action of its spring load is removed, thereby releasing the securing pin to fix the bolt. The securing pin is not manipulable after its release by removal of the housing part and the retaining arm because it is neither visible nor accessible through the cavity in the housing through which the retaining arm extends.