is shown having a mast 22 substructure 24 and a frame 26 which helps support and stabilize mast 22 on rig substructure 24 also shown is a top drive drilling unit 28 suspended from cable arrangement 30 a portion of which loops around crown block 32 and in turn is tensioned for upward movement by motor 34 supported at the rig floor a drill string 36 is suspended by top drive drilling unit 28 which includes a power swivel to rotate the drill string 36 the drill string 36 passes through rig substructure 24 into the ground 38 top drive unit 28 includes a carriage assembly 40 which moves along torque track 42 torque track 42 is comprised of a series of track segments 42a 42e at its upper end torque track 42 is suspended by a cable 44 which is attached to the structural framework of mast 22 at its lower end torque track 42 is attached by member 46 back to mast 22 and a frame 26 the tieback shown in fig2 is also referred to occasionally as a strong back in this manner any torsional load which is introduced into torque track 42 is resisted by the strong back frame arrangement which transmits most of the torsional loads and forces into substructure 24 rather than mast 22 referring still to fig1 a pipe handling ramp 48 is shown adjacent substructure 24 typically such a ramp is used to support sections of drill pipe but in the case of the present invention it is used to support segments 42a 42e of track 42 during assembly as discussed below referring now to fig3 8 the present invention is comprised of a series of track segments 42a e as shown in fig1 however the invention may comprise any number of.