Abstract: A force-developing device for forceps of the type equipped with two jaw elements (2, 3) and with two handles (4, 5) includes a jaw (6A). A link rods system (6B) is articulated with the jaw (6A). A front end of a piston (7) is connected to the link rods system (6B). The piston is housed slidingly inside a first handle (4). A yoke (8) is provided for holding the second handle (5) relative to the first handle (4). A pair of complementary racks (9) mechanically drive the piston (7), the pair being borne by each of the two handles (4, 5). A trigger catch and a rack for preventing the return of the piston are borne by the first handle (4). The pair of complementary racks (9) for driving the piston (7), the trigger catch, and the rack acts alternately on the piston so that by successively moving the second handle (5) towards and away from the first handle (4), the piston (7) is moved forwards and the jaw (6A) is deformed by means of the link rods system (6B).

Abstract: A tightening wrench (5) carrying a measuring cell (8) freely mounted in the hollow part (4) of a wrench (5) and adapted to bear against an end of the pin (2) subjected to the pretension. A detector emitting and receiving ultrasounds (21) disposed inside the measuring cell (8) is made to bear against the end of the pin (2) by a spring (25) interposed between the cell (8) and the detector (21). The cell (8) itself bears against the end of the pin (2) through the action of a leaf spring (9) carried by the wrench (5).