Patent ID: 8651786

Claim:
A fastening device for mounting on a mounting rail comprising: a rear-engagement member configured to be introduced into a mounting opening and to engage behind rims of the mounting opening of the mounting rail; a tensioning device cooperating with the rear-engagement member and having a longitudinal axis, for clamping the fastening device to the mounting rail; a contact plate for resting on an outside of the mounting rail, the contact plate having a feed-through opening for at least a part of the tensioning device; a spring element configured between the contact plate and the rear-engagement member for preloading the rear-engagement member circumferentially with respect to the longitudinal axis of the tensioning device; a holding device between the rear-engagement member and the contact plate for holding the rear-engagement member in the preloaded position; upon release of the holding device, the rear-engagement member being movable by the spring element from an insertion position to a rear-engagement position where the rear engagement member engages behind the rims of the mounting opening; and at least one stop element having a stop face for limiting a capacity of the rear-engagement member for twisting rotation by contact between the stop face and the rear engagement member in the rear-engagement position, the stop element being provided on the contact plate.