systems which dramatically ramp up and ramp down the speed of the gearbox for attempting to stay within rate of penetration settings such lack of precision in conventional systems is the product of a lack of precision feedback and control of the present system and of the use of conventional air motor drives for draw works gearboxes which of course cannot be controlled with any precision the rpm of electric motor 82 is as mentioned above the product of the signal output of vfd 75 and for reasons described hereafter will be that substantially constant rate which optimally maintain the rop which will in turn assure the desired wob plc 70 continuously compares the desired wob to the extrapolated wob and adjusts the rpm of motor 82 in such a way that when balanced against the mechanical effect of movement of drum 22 via a conventional drum unit flexible shaft and overriding clutch mechanism not shown separately in the drawings cable 90 and with it brake handle 34 are drawn to a degree that the desired wob via precise management of the rop is maintained in other words by substantially constantly measuring the wob and adjusting the rpm of motor 82 plc 70 ensures that a substantial state of equilibrium exists between the tension on cable 90 and brake handle 34 and the opposite tending forces of the mechanical feedback from movement of drum 22 such that the desired rop and wob are constantly assured the precise management of rpm of electric motor 82 and with.