Strap tensioning device

The fastening device is operated by a locking lever (3), fitted with a force limiting lever (13), pivoted on to the main lever using linkage mechanism (27, 39, 47). This mechanism is designed to automatically declutch, when the applied force reaches a pre-set value. It consists of an index profile (27) formed on one (3) of the levers, and which co-operates with an indexation element (39), mounted to slide on the surface of the other lever (13). An elastic element (47) maintains the indexation element and profile in contact.