| 摘要 |
Method for driving roof bolts into suitably yieldable strata comprises upright urging a roof bolt in end-on relationship towards a strata face, striking the roof bolt with a vibrating hammer to drive the bolt into the strata face, wherein the hammer is associated with a double acting piston and cylinder arrangement, and causing the hammer to vibrate by supplying thereto an alternating supply of hydraulic fluid under pressure to cause the hammer to move to and fro and thereby drive the roof bolt into the strata. |
