Abstract: The subject matter of this invention is an underground directional drilling tool which is particularly effective in drilling rock and highly compacted soil formations. This tool is an improvement upon the tool developed by Applicants and patented in U.S. Pat. No. 6,050,350. The current invention utilizes ball bearings contained within subassemblies positioned at each end of the steering tool. This allows the steering tool to float upon the subassemblies as the inner core and drive shaft rotate within the subassemblies and steering tool, thereby reducing rotational torque transfer from the drill string, subassemblies and drive shaft to the housing of the directional drilling tool. The use of the ball bearing containing subassemblies improves underground stability and, thus, steerability during the forward drilling operation. Further, these improved features reduce wear thereby increasing durability of the tool which is used in the harsh underground environment.

Abstract: An underground directional drilling steering tool for use with a variety of commercially known drill bits which controls the direction of drill while the drill bit is directly powered by the drill string by way of a drill string coupling. The offset transmitter housing retains the tool in a stable orientation downhole by means of the drill string coupling offset orientation in the housing and stabilizing fins affixed to the exterior of the offset transmitter housing. The positioning of the drill bit in relation to the positioning of the offset transmitter housing in the center of the borehole creates a drilling pathway with a constant curvature away from the wide side of the offset transmitter housing. The direction of this curvature is controlled by means of a jaw clutch, which jaw clutch is engaged by drawing back slightly on the drill string thereby retracting the drive shaft and pulling the drill bit coupling within closer proximity to the offset transmitter housing.