external linkage means 68 separate from the bridge 67 and having different structural and mechanical properties are placed along each side of each anchor slips 58 and its end are connected to slip members 66 as shown in fig9 each link 68 is a steel bar 68 of stainless steel u2014 such as sae 1020 u2014 for greater ductility having a cross section of 2 mm 2 and its ends are bent 90 u00b0 and inserted in holes 69 made in each slip member 66 the sidewalls of the slips 58 have grooves 71 for housing the linkage bars 68 and keep them in the holes 69 of the anchor slips 58 in this way the cemented steel material contributes its typical hardness to anchor slips 58 and the external linkage bars 68 relative ductility less prone to failure from jarring and thermal excursions which may fracture an anchor slip 58 the bridges 67 of the slips 58 are not thermally treated and hence remain ductile first the entire piece 58 is cemented then only the region of the teeth 63 is induction or flame heated and the entire piece 58 is tempered in this way the slips 58 are hard in the region of the teeth 63 and ductile in the region of the bridge 67 so that in spite of the latter being the narrower part of the piece 58 a fracture is more likely to occur in the region of the slip members.