Results 81 - 85 of 85

• Horizontal Trajectories of Rotary-Drilled Holes
  1/1/1988 - Reports of Investigations
  This Bureau of Mines report investigates the horizontal trajectory of boreholes drilled in coalbeds using the rotary drilling technique.
• Test Apparatus for Measuring Sound Power Levels of Drills
  1/1/1987 - Information Circulars
  This Bureau of Mines report describes in detail the design and operation of a test apparatus for measuring the sound power levels of drills used by the mining industry.
• Comparison of Rotary and In-Hole Motor Techniques for Drilling Horizontal Boreholes in Coal
  1/1/1985 - Reports of Investigations
  This Bureau of Mines report describes and compares the procedures, capital investments, and operating costs of rotary and in-hole motor drilling techniques used to drain methane gas from the Pittsburgh coalbed in an underground mine located in southwest...
• Noise Reduction of a Pneumatic Rock Drill
  11/1/1975 - Reports of Investigations
  Data are presented on the individual and combined effects of Bureau of Mines modifications on standard pneumatic rock drills in reducing noise.
• Rotary Drilling Holes in Coalbeds for Degasification
  1/1/1975 - Reports of Investigations
  Coal is a soft and brittle material. Drilling rates in the Pittsburgh coalbed using a drag bit exceed 3 ft/min at 2,500-pound thrust. However, maintaining the bit on a horizontal trajectory or parallel to bedding planes to attain lengths of 1,000 feet i...