and driven thereby by a prime mover not shown in a manner known in the art the lower portion of gripper chains 34 and 35 are supported by gripper chain idler sprockets 40 and 41 respectively mounted on idler shafts 42 and 43 gripper chains 34 and 35 are of a kind known in the art and each has a plurality of outwardly facing tubing gripper blocks 44 thereon as best seen in fig3 each gripper block 44 has a v shaped groove 46 defined on the outer face thereof the v shape of groove 46 allows the blocks to automatically adjust for different diameters on tubing string 16 that is a larger outer surface 48 on tubing string 16 will be positioned further outwardly in groove 46 than a smaller diameter portion drive sprockets 36 and 37 and idler sprockets 40 and 41 are biased toward tubing string 16 in a manner known in the art so that gripper chains 34 and 35 generally conform to the outer surface of tubing string 16 as seen in fig2 when tapered connector 10 passes through injector 20 gripper blocks 44 will grip along tapered outer surface 48 thereof gripper chains 34 and 35 are rotated in opposite directions so that the gripper blocks 44 on both which engage tubing string 16 move downwardly to force the tubing string into the well this can be reversed to pull tubing string 16 out of the well the v shaped grooved surface of gripper blocks 44 in the halliburton injector allow the differing outer surfaces of tubing string 16 to be substantially simultaneously engaged referring now to fig4 a cross section of the portion of tubing string 16 which includes tapered connector 10.