GB528466A - Improvements in or relating to suspension bridges - Google Patents

Abstract

528,466. Suspension bridge; ground anchors. DORMAN, LONG & CO., Ltd., PAIN, J. F., and FREEMAN, R. May 8, 1939, No. 13683. [Class 20 (i)] [Also in Group I] The wires of each row which form a composite cable for a suspension bridge are carried simultaneously across the span maintaining a predetermined positional relationship, and the tension in the cable is controlled by exerting a restraining force on the cables during their movement. The wires for the cables are: carried by drums mounted on rotary turntables (not shown) and are led in rows, simultaneously therefrom, through guides and tensioning devices, a number of rows being superposed, each row being compacted at the ends and having a separate anchorage. The wires for each row are led through grids 12, then through spacers 20, 21, over the lower members of roller tensioning devices 15 with spacers 19 between each set of rollers, through a further spacing device 21, thence over a rubber faced block 36, around a guide roller 37 and the ends are attached to a spreader frame 38, Fig. 8, the wires being then tightened by rotating the turntables backwardly.. The upper roller frames, upper members of the spacers, and upper blocks 35, are then placed in position and the tensioning device 15 adjusted, whereupon the spreader frame is drawn forwardly some distance, the formation of the wires between the spreader frame and the guide roller being maintained by loose clamps at intervals. The ends of tHis row of wires are then compacted into a cable by means of a cramp comprising two bifurcated members 51, 53, Fig. 9, capable of adjustment by screws 52, bound with soft wire, and secured in a socket 6. This socket is then drawn across the span by a haulage rope, the wires resting on nests of rollers, adjustably connected to the bridge towers, the loose clamps being removed and refitted when passing the towers, and the sag of the wires being set by a pilot cable and controlled by the adjustable pressure device 15. The socket is then drawn over an anchorage strut 5, Fig. 10, and attached to its allotted anchorage wire 7, which is secured to a plate 8 embedded in concrete, the wires are arranged on the saddles of the towers in their correct positions, the sag finally adjusted and thereupon the ends of the wires between the turntables and tensioning devices 15 are compacted by the cramp 51, 53, cut, bound, and fixed in a socket and after removal of the tensioning device connected to its anchorage. The operation is repeated for each row, the rows being superposed on the saddles of the towers to form a composite cable as shown in Fig. 15, this cable comprising forty rows. The spacer 20, Fig. 6a. comprises a lower apertured plate 29 to support rollers 32 and a slotted upper plate 28 adjustably fixed to the lower plate. Each spacer 21, Fig. 7a. comprises upper and lower plates 22, 23 joined together at their ends, and provided with a gateway through which the wires are passed, this gateway being closed by a projection 27 on a lever 26.