| 摘要 |
WO 90/06418 discloses a dynamic torque transmitting arrangement which inhibits a power tong and a back-up tong tending to move out of the axial alignment whilst coupling or uncoupling adjacent pipes. In the mechanical arrangement disclosed the minimum distance between the power tong and the back-up tong is limited by a str ap. In the present invention flanges (122) are mounted on opposite sides of the top of the power tong (102). Tension arms (119, 120) are pivotally mounted on the flanges and are connected by a hollow tube (121). Straps (117, 118) are pivotally mounted at one end to the tension arms (119, 120) and at the other end to hollow pillars (115, 116) on which the back-up tong (105) is slidab ly mounted. When the power tong (102) and the back-up tong (105) are in close proximity, the straps (117, 118) are disposed to either side of the power tong (102). The back-up tong (105) is supported from the power tong (102) by rods (108, 109) which are c onnected to plates (112, 113) on which the hollow pillars (115, 116) rest.
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