in conducting pressured fluids into and from the cylinder for operation of the slip assembly the cylinder has a rod 13b having a hole 13c in which is mounted a bearing 18 an operating arm 19 has rod portion 19a which is inserted through a hole in the bearing pivotally connecting the operating arm and operator the connection is secured with pinned castle nut 20 mounted between the upper and lower plates are three identical ring segments 21 spaced 120 degrees apart and positioned by upper and lower ring segment extensions 21a protruding into mating grooves 11b and 12a in the lower and upper plates with pairs of top and bottom bolts 22 passing through holes in the upper and lower plates and screwed into threaded holes in each ring segment fastening each ring segment to the upper and lower plates between the upper and lower plates are rods 23 having pin portions fastened in flat bottom holes in the lower plate with bolts 24 securing a cover 25 and the upper plate to these rods each ring segment 21 has a large radial groove 21b and a small wider groove 21c cut inside housed in the larger inside segment grooves is an outer bearing race 26 of sealed ring bearing 27 having seals 28 and an inner race 29 the inner race has holes 29a spaced 120 degrees apart and is housed.