| 摘要 |
A down the hole drill includes a piston and cylinder assembly with the piston forming the drill hammer. The drill is powered by an air supply. The cylinder is divided into a plurality of longitudinally extending contiguous sections and the piston is shaped to provide, with the cylinder, a drive and lifting chamber in each section. The air supply and exhaust are provided in separate passages in a control rod which extends along a bore in the piston, the latter providing a piston head in each section of the cylinder. The invention provides a larger operational surface area and provides for greater pressure to be applied thereto than is presently possible for a particularly sized drill.
|
