PNEUMATISCHE SCHLAGMASCHINE

摘要

The pneumatic percussion machine includes a hollow casing; a valve assembly at one end of the casing; a bit assembly at the other end of the casing; a piston adapted to reciprocate in the casing between the first position in which it is in contact with the bit assembly and a second position in which it is removed from such first position; a first chamber formed between an end of the piston and the valve assembly; a second chamber formed at or towards the other end of the piston; a first fluid supply path through the valve assembly to the first chamber; a second fluid supply path through the valve assembly to the second chamber, such second fluid supply path passing for at least part of its length through the piston; a first fluid discharge path from the first chamber passing, for at least part of its length, between the wall of the casing and the piston, such fluid discharge path being open inparticular positions of the piston along the length of the hollow casing; the arrangement being one in which the valve assembly is adapted, on operation of the machine, to open alternatively the fluid supply paths.