Patent GB-1378782-A (GB)
Title: Twin-clamp traction apparatus for cables or rods
IPC: B66D3/02
Filed: 1972-02-11
Abstract: 1378782 Cable clamps TRACTEL SA 11 Feb 1972 [12 Feb 1971] 6400/72 Heading F2X A twin-clamp traction apparatus for hauling and hoisting cables or rods comprises a casing 1 with aligned sockets 3, 4 at opposite ends, a hollow rod 5 of a fastening member, e.g. an anchor hook 6, being slidably fitted within the socket 3. A free end 7 of a cable is passed through the hollow rod 5, and the socket 4 receives a loaded end 8 of the cable. A compression spring 9 mounted between the socket 3 and a collar 10 integral with the hollow rod 5 urges the casing 1 away from the hook 6 which is integrally assembled by means of a head 11 with a member 12 carrying bearings (Fig. 2, not shown) for supporting a forward-motion transverse crank-shaft 14. These bearings can move longitudinally in elongated apertures in the casing 1. A reversemotion transverse crank-shaft 17 extends across the opposite end of the casing 1. Pairs of control links 22, 24 and 23, 25 operate jaws 20, 21, respectively. Each pair of links comprises two lateral links disposed on opposite sides of the respective jaw, the links acting upon camforming bosses carried by the jaws and engaging suitable recesses formed in the links. Each link carries a trunnion adapted to pivot and slide in guide rails carried by the inner wall of the casing 1, e.g. by means of roller bearings. In the embodiment illustrated, the cams of the jaws and the corresponding recesses of the links are so designed that the links 22, 24 tighten the jaws 20 by pivoting in the counterclockwise direction, while the links 23, 25 tighten the jaws 21 by pivoting in the clockwise direction. The two pairs of links 22, 24 are interconnected by an upper coupling rod 28, and the other two pairs of links 23, 25 are interconnected by a lower coupling rod 29. Crank-shaft 14 is connected to the links and therefore to the two clamps through two pairs of connecting-rods 30, 31 which are attached to the upper ends of links 22 and to the lower ends of links 23, respectively, so that any movement of crankshaft 14 in either direction will cause the clamps to move in opposite directions so as to tighten the clamp being pulled towards the hook 6 while releasing the clamp pushed in the opposite direction (hauling action). Crank-shaft 17 is connected to the links and therefore to the two clamps through two pairs of connecting- rods 36, 37 which are attached to the lower ends of links 24 and to the upper ends of links 25, respectively, so that any movement of crankshaft 17 in either direction will cause the clamps to move in opposite directions so as to tighten the clamp moving away from hook 6 while releasing the clamp moving in the opposite direction (hauling-off action). After the cable (or a rigid rod) has been introduced through the apparatus, a reciprocating motion is applied by means of an external lever either to crank-shaft 14 for hauling the cable or to crank-shaft 17 for releasing or hauling-off, i.e. for paying-off in a controlled manner the loaded cable end 8. In either case a reciprocating motion attended by a displacement of the two clamps in opposite directions is imparted to the jaws 20, 21 of the clamps. Upon each reversal of the crank-shaft movement, the links begin to pivot from one position to the other, whereby the previously released jaws become tightened while the other jaws are released to permit sliding movement of the cable through the open jaws. As a certain wear develops in the clamps or the cable, the clamping remains effective due to the automatic displacement of the casing 1 in relation to the anchor hook 6. With the hook 6 attached to a fixed point, the casing 1 can move to the right and given the same position of crankshaft 14, the jaws will move to the right as shown in broken outline. A constant preclamping effect is therefore obtained in spite of a possible wear of the cable and/or the jaws, or the use of a cable of smaller diameter.