Drilling arrangement and drilling feed mechanism

摘要

PCT No. PCT/GB94/00828 Sec. 371 Date Oct. 18, 1995 Sec. 102(e) Date Oct. 18, 1995 PCT Filed Apr. 19, 1994 PCT Pub. No. WO94/24408 PCT Pub. Date Oct. 27, 1994A drilling arrangement wherein a cylinder of a multistage telescopic feed mechanism acts on a drill to move it in a first direction and two pistons extend from the cylinder only in a second direction opposite to the first direction, acting against a feed beam.