Abstract: A power tong unit which is operable as a closed head or open head unit. The jaws of the tong unit are rotatable to an extended pipe gripping position from either of opposite directions to make-up or break-out pipe from a single retracted position. An improved reversal means controls the direction of rotation of the jaws between the make-up and break-out positions.

Abstract: Disclosed herein is a large diameter earth boring bit with improved nozzle placement. The bit is of the type having a cutter support with several rotatable cutters mounted below. The bit is connected to a string of pipe having an input and a return flow passage. Nozzles are located on the cutter support for the discharge of fluid onto the borehole bottom to sweep cuttings into an intake port in the cutter support. An outer zone nozzle is located at the periphery of the cutter support for cleaning the gage area of the borehole.Several inner zone nozzles are spaced between the periphery and the intake port. The inner zone nozzles are positioned so that the area of influence of each nozzle overlaps with its next inward nozzle. This creates a continuous stream that entrains cuttings and sweeps them to the intake.