| 摘要 |
<p>The invention relates to a novel attachment means useful in fixedly interconnecting polygonal drill steel to a rock bolt dolly when the drill steel is inserted into complementary socket means provided at one end of the dolly. Heretofore, accidental disengagement of the drill steel from the dolly was relatively common often resulting in injury to workers and lost operating time. When in their socketed mode, a length of mild steel rod is welded along one of its end portions to the rock bolt dolly and the other end portion is tightly wound about the drill steel so that this winding abuts a collar on the drill steel intermediate the rock bolt dolly and the winding when the drill steel is socketed to the dolly.</p> |
