Air-operated reversible percussive action machine

An air-operated reversible percussive action machine predominantly for making holes in the ground, comprising:

• a housing having front and rear portions;
• a reciprocating hammer positioned in the housing and provided with a cavity and a first port through which the cavity communicates with a chamber of the housing;
• a stepped tube secured to the rear portion of the housing and having an interior, the stepped tube having a larger diameter step with a second port and an end face at a free end of said tube, the larger diameter step being positioned in the cavity of the hammer so as to alternately close the first port of the hammer and provide communication with the second port;
• a sleeve positioned within the interior of the tube, the sleeve having a third port communicable with a compressed air line, the sleeve being capable of turning relative to the tube to assume one of two positions, in one of which the second port of the tube is closed, and in the other position, the second port of the tube communicates with the compressed air line through the third port;
• at least one first projection in the form of a sector of a circle formed on the end face of the larger diameter step;
• at least one radial projection arranged on a respective end of the sleeve so as to abut against a side wall of said at least one first projection of the tube when the sleeve is rotated, whereby said sleeve-assumes one of said two positions;
• at least one additional annular elongated projection provided about the circumference on the end face of the larger diameter step and spaced from the at least one first projection;
• and
• the at least one first projection having a length greater than the length of the at least one additional projection, wherein the sleeve is capable of moving relative to the tube in an axial direction thereof for a distance greater than the length of the at least one additional projection and less than the length of the at least one first projection.