of the track unit and extending laterally from the track unit the torque absorber unit preferably comprises at least one hydraulic cylinder 18 horizontally mounted to the drilling rig floor structure the cylinder contains a movable piston 20 and a horizontal piston shaft 22 connecting the piston to the base plate the piston shaft is preferably pivotally connected to the base plate more preferably the at least one hydraulic cylinder is mounted to the drilling rig floor structure for pivotal movement in the horizontal plane and the horizontal piston shaft is pivotally connected to an outer end of the base plate for pivotal movement in the horizontal plane the piston divides the hydraulic cylinder into a first chamber and a second chamber the apparatus preferably further comprises a fluid supply means 24 operatively connected to the hydraulic cylinder for driving the piston to a desired location in the hydraulic cylinder see fig3 the hydraulic cylinder applies rotational torque to the track unit which is transmitted to the power swivel via the track the carriage unit and the at least one pair of linkage arms so that the power swivel is selectively rotatable from a first rotational position to a second rotational position in a variable manner the same apparatus is thus useful for both torque reaction and pipe handling i e it has dual functionality additional functionality can be achieved by providing a pressure indication means 26 operatively connected with the fluid supply means to provide an indication of fluid pressure in the hydraulic cylinder this enables the.