Compression-vacuum action percussive machine

A compression-vacuum action percussive machine comprising:

• a casing (1) accommodating a tool (7) at one end thereof;
• a cylinder (2) within the casing (1) for housing a piston (3) adapted to reciprocally move within the cylinder (2);
• a striker (4) having an extension (9) including an end face formed by a chamfer (10) facing the tool (7) for impacting on the tool (7) and being separated from the piston (3) by a cushion of air (5);
• and
• means for trapping the striker comprising, a sleeve (11) coaxial with the striker (4) and having an end facing the striker (4) and an annular groove (13) formed within an inner wall (12) of the sleeve (11) containing a resilient ring (14) wherein a portion of the resilient ring (14) conforms to the shape of the annular groove (13), an inner annular rib (15) between the annular groove (13) and said end of the sleeve (11), wherein the diameter (d) of the annular rib (15) is smaller than the diameter (D) of the inner wall (12) of the sleeve (11) and greater than the diameter of the extension (9) at the end face, and the inner diameter of the resilient ring (14) is smaller than the diameter of the extension (9) of the striker (4).