| 摘要 |
PCT No. PCT/GB94/02192 Sec. 371 Date Oct. 30, 1995 Sec. 102(e) Date Oct. 30, 1995 PCT Filed Oct. 7, 1994 PCT Pub. No. WO95/10686 PCT Pub. Date Apr. 20, 1995A positioning apparatus for moving a power tong (110) between an operative and an inoperative position is a drilling tower (105) comprises a first arm (102) and a second arm (103). One end of the first arm (102) is pivotally connected to one end of the second arm (103) at pivot (106) whilst the other end of both the first arm (102) and the second arm (103) are pivotally mounted on a beam (104) attached to the drilling tower (105). Both arms (102, 103) can be extended and retracted in unison to move the power tong (110) towards and away from its operation position circumjacent a pipe string.
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