Twin clamp traction apparatus for cables or rods

Claim 1

Traction apparatus for cables or rods comprising tan-dem traction clamps capable of performing simultaneous alternative and reverse movements and to act upon a cable or bar extending through the apparatus, a closed casing, an anchoring member at one end of said casing, a pair of said clamps being disposed within said casing with one clamp in the vicinity of the other clamp in the direction of the cables or bar axis, each clamp of said pair of clamps having a pair of jaws surrounding said cable or bar and presenting a pre-clamping action on said cable or bar, pairs of control links associated to each clamp and presenting cam surface co-acting with cam shaped portions of lateral surfaces of the jaws of each of said clamps, the cam surfaces of the ones of said control links acting on the jaw of the one of said clamps being disposed symmetrically to the cam surfaces of the ones of said control links acting on the jaws of the other of said clamps with relation to a plane perpendicular to the cable or bar axis, a forward motion crankshaft transversely mounted in bearings of said casing, a first connecting rod pivotally connected to an upper extension of said forward motion crankshaft and connected to the control links of one of said clamps, a second connecting rod pivotally connected to a lower extension of said forward motion crankshaft and connected to said control links of the other clamp so that upon the pivoting of said forward motion crankshaft in one or the opposite direction causes the clamping of one of said clamps and the opening of the other clamp and inversely together with a relative axial movement of said two clamps thus insuring the pulling of the cables or bar, a reverse motion crankshaft transversely mounted in bearings of said casing, a third connecting rod connecting said reverse motion crankshaft to said control links of the other of said clamps, a fourth connecting rod connecting said reverse motion crankshaft to said control links of one of said clamps so that upon the pivoting of said reverse motion crankshaft in one or the opposite direction causes, inversely with respect to said forward motion crankshaft, the opening of one of said clamps and the clamping of the other of said clamps together with a relative axial movement between said two clamps insuring the hauling out of the cable or bar, the transverse axis of said forward motion crankshaft and that of said reverse motion crankshaft being disposed in a common fixed plane containing the cable or bar axis and the pivot axis of said control links and at least one of said forward motion crankshaft and reverse motion crankshaft being movable in the direction of the cables or bar axis to adjust the pre-clamping action of said jaws of each of said clamps according to the cable or bar diameter, longitudinal guide rails provided on the inner faces of said casing, and rollers mounted on external faces of said control links, concentrically to their pivot axis, which are adapted to move along said guide rails during the translation motions of said clamps.