Abstract: A grinder constituted by a ring (10) having a horizontal axis, a mechanism for driving the ring in rotation about its axis, at least one roller (16) the axis of which is parallel to that of the ring and which is placed inside the latter so as to be able to travel over its internal surface and elastic member (30) for pressing the roller against the ring, the roller being supported at its ends by two arms (22) mounted on the frame of the grinder so as to be able to pivot about an axis parallel to the axis of the ring.

Abstract: A grinding apparatus for forward feeding material in a drum in which the grinding apparatus has a circular grinding track therein. The drum is driven in rotation at a speed such that material therein is held on the circular grinding track by centrifugal force. A knife is positioned in an upper descending portion of the drum for detaching material from the circular grinding track. A deflecting plate is disposed beneath the knife so as to receive materials detached by the knife and to divert the detached materials toward the output of the drum. The knife is disposed such that the knife has an active face forming an angle of between +15° and −50° with a radial plane extending between a horizontal axis of the drum and an edge of the active face.

Abstract: A grinder having an annular track with a horizontal axis (14), a roller (16) capable of travelling over the track, a mechanism for pressing the roller against the track and means (18) for displacing the material from one edge of the track to the other in such a way that it passes several times beneath the roller before being evacuated. To enhance the efficiency of the grinder and the distribution of mechanical stresses in the roller and the track, the track (14) and the roller (16) are designed in such a way that the gap between them decreases from the edge of the track (14) located on the side for supplying the material to be ground to a distance from this edge at least equal to 80% of the width of the track, and in that this interval then swiftly increases to form a decompression area (19) on the ground material evacuation side.

Abstract: A cap (1) has a housing (9) adapted in order to receive one end of the pin (2), and a tapped hole (11) opening out transversely in this housing, adapted in order to receive a fixing screw (12) allowing the pin (2) and the cap (1) to be solidly attached together; the screw (12) is initially made in a single piece with the terminal part ( 4 ) of a handle (7) of the fixing instrument (3), an embrittled zone (13) being made at the transition between the screw and the terminal part (4). The surgeon first covers the pin (2) with the cap (1), then screws the screw (12) until it locks the pin (2), and the end of screwing causes the embrittled zone (13) to rupture, so that only the screw (12) remains locked in place in the cap (1) fixed to the pin (2). This cap prevents any migration of the pin and protects the neighbouring tissues.