Hydraulically operated impact drill - has cross bar driving tool, supported at each end by hydraulic shock absorber piston

摘要

The hydraulically driven impact drill, designed for efficient operation when used against the roof of a tunnel, has a head with a bar (3) carried horizontally across it. This passes through a slot across the stem (2) of the drilling tool for driving it. Each end of the bar is supported by a shock absorber (4) with a cylindrical piston (5) through it, at right angles to the bar. Each piston has a helical line of holes n11) through it to reduce the pressure of the hydraulic fluid, operating inside a chamber (6) filled wiht hydraulic fluid, underneath. This communicates with a ring shaped chamber (7) around the bottom of the piston. In another design, a return spring is mounted under each piston.