Single-blow pneumatic percussive tool

PCT No. PCT/SU86/00118 Sec. 371 Date Jul. 19, 1988 Sec. 102(e) Date Jul. 19, 1988 PCT Filed Nov. 20, 1986 PCT Pub. No. WO88/03855 PCT Pub. Date Jun. 2, 1988.A single-blow pneumatic percussive tool comprises a hollow cylindrical casing (1) accommodating a reciprocatable hammer piston (2) which divides the interior space of the casing (1) into an upper and a lower chambers (3, 4). A spring-biased valve (5) is mounted on the side of the lower chamber (4) and a working member (6) is secured to the valve (5). An air distribution device (7) is mounted on the side of the upper chamber (3) and has passages (8, 9, 10) and a control lever (11). The hammer piston (2) has an axial passage (13) in which a tube (14) is mounted which has a shoulder (15) on the outer surface and a continuous inner partition wall (16). The tube (14) has upper and lower ports (17, 18) disposed on either side of the partition wall (16). An air distribution sleeve (19) biassed by spring on the side of the air distribution device (7) is mounted on the tube (14) and has an inner recess (21). The air distribution sleeve (19) is movable under the action of the hammer piston (2) to the upper position in which it covers the lower ports (18) and the air distribution sleeve (19) is movable under the action of a spring means (20) to the lower position defined by the shoulder (15), in which it establishes communication between the upper and lower ports (17, 18) through the inner recess (21).