Abstract: A method and apparatus for manipulating and deploying lengths of pipe when drilling wells is provided. The apparatus has a motor assembly with a rotor shaft coupled to a drive gear, and a torque assembly with a planetary gear set coupled to the drive gear of the motor and an annular gear. Planet gears are coupled to a torque converter, which is coupled to a stub for connecting to pipe joints. The torque converter has inclined surfaces for circulating lubricant through the gear assembly, and the planet gears have openings in registration with the inclined surfaces. A drilling fluid pipe is disposed through the rotor shaft of the motor assembly, and is coupled to the torque converter. Lead-screw linear actuators position an elevator, which hangs from links hooked to the apparatus, to manipulate the drill string, and a self-locking pipe jaw handles pipe joints.

Abstract: A gear reversal mechanism for a hand held power tool is selectively operative to reverse the output of a unidirectional motor and provides a direct drive forward mode and an indirect drive reverse mode, with the selection therebetween being implemented by a manual shift collar operating a cam mechanism selectively to reorient the gear train and consequent direction of motor output. The shift collar is temporarily locked to the gear housing during tool operation by using the operative air pressure of the tool to expand a locking mechanism into locking engagement with such shift collar. With or without the locking mechanism, an exhaust shutoff shift interlock may be provided to permit exhaust air to exit the housing when the shift collar is in either its forward or reverse operating positions or alternatively to close the housing exhaust ports to block exhaust air flow to preclude motor operation when the shift collar is between its operating positions.