Abstract: A roller-reamer stabilizer having a plurality of roller cutters mounted in recesses in the supporting body such that each roller is free to rotate in its own bearing blocks. The cutters and bearing blocks are provided with air bleed lubrication and cooling from a central bore in the supporting body as is common and well known in the art. The present invention deals with the supporting body of a roller-reamer stabilizer of the near bit type and in particular one that would be used in the mining blast hole drilling industry. This supporting body is characterized by having a profiled lower end having maximum diameter outer surfaces separated by minimum diameter relief areas. The maximum diameter surfaces are, respectively, aligned with the cutters and extend upwardly from near the lower surface of the body to encompass the lower bearing blocks. The minimum diameter relief areas extend further up the body and terminate level with the upper bearing blocks.

Abstract: An order wire system which can be used during installation and maintenance of an optical fiber communication system comprises an optical fiber order wire to which engineers can connect at remote sites communication sets each of which includes a microphone and earphone allowing the engineers to communicate with each other. Full duplex and multi-party operation can be achieved with the sets according to the invention and, because the signals are regenerated, the range of operation is considerable. Both analog and digital communication is contemplated and different specific circuits are proposed. In a typical analog configuration, the microphone output is fed to first and second frequency modulators operating respectively at first f.sub.1 and second f.sub.2 center frequencies. The outputs of the modulators are summed and passed to a laser driver and laser which is optically coupled both to the upstream and the downstream side of the order wire.

Abstract: The invention relates to a guide bushing used to maintain alignment of a rotary shaft and in particular to a guide bushing for use as a mining deck bushing. When drilling blast holes in surface mining operations, it is conventional to pass the drill pipe through a deck bushing located on the floor or deck of the blast hole drill. During drilling operations the drill pipe has a tendency to run off laterally, and vibrate vertically. The purpose of the deck bushing is to keep the drill pipe as straight as possible, and prevent wear of the more costly deck. The present invention provides a guide bushing for use as a deck bushing and is equipped with a rotatable inner sleeve which is supported by angular journal bearing surfaces and ball bearings located in elongate annular grooves, which allow the guide bushing to maintain alignment of the drill pipe without premature failure of the ball bearings, grooves or other bearing surfaces.