| 摘要 |
The backup tong 10, 110 includes a fluid powered cylinder assembly 72, 172. A wedge 80, 180 is provided at the end of a cylinder rod 76, 176 and forces multiple dies into gripping engagement with the tubular. A pair of links 30, 32 or 130, 132 are driven laterally outward from the centerline 28, 128 of the tong body by the wedge 80, 180, thereby forcing the dies to bite the tubular. The design of the tong is relatively simple and has few moving parts, yet is highly rugged and dependable. Dies 62, 64 and 66 or 162, 164 and 166 may together provide circumferential engagement of at least 270 DEG with a tubular, thereby reliably gripping and minimizing damage to the tubular. The tong 10 includes a door jaw latch pin 58, and is particularly well suited for use on dual tubing strings where there is little axial spacing between the tubing strings.
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