GB250864A - Improvements in or relating to tongs and carriages - Google Patents

Abstract

250,864. Smith, N. K. April 6, 1925. Borehole apparatus.-A pipe tongs comprising a yoke and two pivoted levers which lock together round a pipe is provided with latch means for holding the levers open in any desired position to facilitate adjustment of the tongs round a pipe &c. The pipe tongs which may be suspended in balance on chains 52 comprises two swinging arms 17, 18 pivoted one at each end of upper and lower arcuate plates 11 connected by a web. The plates have gripping edges A, Band C of varying diameters. When the arms 17 and 18 are swung inwards towards each other to grip a pipe a projection 24 on the arm 17 takes into a hollow 23 in the arm 18 and further acts on a projection 22 cam-like, so as to make the gripping surfaces 46 bite into the pipe and secure it against the gripping edges of the arcuate plates. The arm 18 is provided with a hand released latch 32, Fig. 2, to secure it in any desired position. The arm 17 is held in open position by the lip 45 of a spring-pressed pivoted dog 44, engaging the lug 24. Gripping discs 46 preferably with diagonal teeth are secured in dovetail slots in the arm 18 by spring-pressed pins. One of a pair of co-operating wrenches, Fig. 7, may be supported in a sleeve 62 on a spring 63 and a pedestal 61 on a rotary table. The lever 51 of the wrench is placed between jaws of the housing 69 and secured by the engagement in a slot in the lever of an eccentric pin turned by a handle lever 78. A latch 83 is swung down to lock the lever 78 in position. Specification 250,752 is referred to.