Abstract: An improved shaft drill break-out system is disclosed that utilizes three separate out-put torques for the power swivel used to break-out, make-up and rotate the drill stem and attached drill bit for earth boring. When removing drill stem from the hole, the power swivel is tightened to the upper end of the drill stem with the largest torque. Thus, when the upper section of drill stem is lifted for breaking the bottom connection from the next lower section of drill stem, it is assured that this bottom connection will be broken since when going in the hole this connection was made-up with the intermediate torque. The lowest torque is used for drilling. As a consequence, sufficient torque for break-out is assured with proper selection of each of the three torques. Additionally disclosed are break-out arms and a slip assembly adapted for selected engagement with vertical slots in the drill stem to facilitate make-up and break-out.

Abstract: A system for use in the make-up or break-out of drill stem members of earth boring machines having a hydraulically operated power swivel to rotate the drill stem and hydraulic cylinders to raise and lower the swivel. A first, variable volume pump supplies fluid to the hydraulic cylinder through a four-way valve. A servo pump controller, connected with this valve and operable by variable resistors, establishes the linear make-up and break-out speeds for the power swivel. A second, variable volume and reversible pump supplies fluid to the power swivel means. A second servo pump controller, connected with the second pump and operable by variable resistors, establishes selected linear rotational travel speeds for the power swivel. Make-up torque is controlled by an electrical solenoid activated pressure compensator connected with the second pump, and linear speed is similarly controlled.