| 摘要 |
A system for drilling holes in the roof of a mine has a flexible shaft 16 comprising a cylindrical outer casing 100 formed by a spring member 102 wound in helical configuration, and a flexible inner assembly that includes an elastomeric core 104 and a series of radially rigid reinforcing segments 110 extending end to end along the length of the flexible shaft. The flexible shaft has improved radial dimensional stability as well as reduced tendency to elongate or otherwise distort. The drive 14 includes the shaft gripping assembly 50 carried by a thrust piston 32. Fluid pressure applied to a flexible sleeve 68 urges a collet 82 to grip the flexible shaft 16, the resulting twisting of the helical outer casing 100 causing the shaft to become rigid at its upper end. <IMAGE> |
