Pneumatic reversible impact device for driving holes in soil

摘要

The device comprises a hollow cylindrical body, pointed front at its end which device accommodates a striker forming the front working chamber in said body, and has a cylindrical space at its rear end. Said space receives an air-distributing and reversing mechanism, thus forming the rear working chamber. The air-distributing and reversing mechanism has a bushing which is fixed relative to the body, and an axially movable bushing, both bushings being arranged coaxially, spring-loaded in the axial direction relative to each other, and forming a chamber located in the front part of said mechanism, with the chamber communicating with a source of compressed air and intended to move the movable bushing during reversal of the device. The side wall of the movable bushing has a through hole and a longitudinal external recess, both made in such a manner that during the forward travel of the device the through hole places the chamber formed by the bushings in communication with the source of compressed air while during the backward travel the through hole is covered by the fixed bushing and the chamber formed by the bushings communicates with the atmosphere through the external longitudinal recess.