| 摘要 |
1301560 Pipe tongs BYRON JACKSON Inc 4 Aug 1970 [20 Aug 1969] 37640/70 Heading B3N Tongs have a jaw actuating means whereby initial closing of a jaw is caused by a roller 34 engaging a cam surface 33a or 33b, on gripping a pipe a resilient means is overcome and the roller rolls between the cam surface and a jaw surface 73 whereby the force for gripping a pipe is a function of the relationship between the cam surface and the jaw surface. As shown, the resilient means comprises shoes 74 slidingly positioned in grooves 75 and biased by springs 76. In another embodiment, Figs. 11-14, not shown, the resilient means is a resilient deformable body (174) of polyurethane disposed non-slidingly in the grooves 75. The jaws are spring biased open and during pipe gripping inner ring plates 9 and 10 are held stationary by a brake band 35. On release of the jaws each shaft 70, which carries aroller, iscentralized in its jaw by the faces 77 of the shoes 74. Also, each follower is prevented from passing a central depression 33c by reverse stop means which includes a travelling stop pin 50, stops 51, 52 and an actuator ring 57 having a cam surface 61. |
