Single-blow pneumatic percussive tool

A single-blow pneumatic percussive tool comprising a hollow cylindrical casing (1) with inlet and outlet ports (2, 3) accommodating a reciprocatable hammer piston (4) which divides the interior space of the casing (1) into lower and upper chambers (5, 6), a working tool (7) mounted in the casing (1) on the side of the lower chamber (5) an air distribution device (8) mounted in a handle (9) installed on the upper part of the casing (1) and having passages (10, 11) for admission of gaseous fluid under pressure to the interior space of the casing (1), a sleeve (12) with ports (13) defining with the casing (1) an intermediate space (14) which communicates at regular intervals with the lower chamber (5) through the outlet ports (3) for admission of gaseous fluid under pressure an air distribution sleeve (15) which is axially biased by a spring;

• and has radial ports (16) and recesses (17) aligned with the radial ports (16) on both surfaces of the air distribution sleeve (15) which is mounted for reciprocations in the intermediate space (14) alternately communicating with one passage (10) for admission of gaseous fluid under pressure and with atmosphere, and the outlet ports (3) of the casing (1) are aligned with the ports (13) of the sleeve (12) rigidly mounted outside the casing (1) the outlet ports (3) being covered by the sleeve (15) when the air distribution sleeve (15) is in the upper position and establish communication of the lower chamber (5) with atmosphere through the radial ports (16) when the air distribution sleeve (15) is in the lower position, the lower and upper chambers (5,6) communicating with each other through at least one passage (18) made in the hammer piston (4) which is biased by a spring on the side of the lower chamber (5).