| 摘要 |
An anchor for a mine roof bolt incorporates a single large rib at the top of a s egmented shell. This single large rib is forced into the wall of the bore hole by the dow nward movement of an associated threaded camming nut during the first few revolutions of the roof bolt. The remainder of the outer surface is generally smooth or unserrated and provides a large bearing surface which is urged against the bore hole wall upon further rotation of the bolt. The camming nut has a specific shape flaring substantially near its upper end such that a relative large area of the bore hole wall below the rib is forced into compression.
|
