Abstract: A compression-vacuum action percussive machine is proposed, which has a casing (1) accommodating a tool (7) and a cylinder (2) with a drive piston (3) and a striker (4) having a chamfer (10) on the end face engageable with the tool (7), and also a means for trapping the striker (4), which means is made in the form of a sleeve (11) with an annular groove (13), wherein a resilient ring (14) is mounted. The sleeve (11) has an inner annular rib (15), the diameter of which is smaller than the diameter of the inner wall (12) of the sleeve (11), the annular rib (15) being positioned at the end face of the sleeve (11) facing the striker (4). The inner diameter (d) of the resilient ring (14) is smaller than the diameter (D) of the extension (9) of the striker (4), which extension is situated after the striker chamfer (10).

Abstract: A compression-vacuum percussive action machine has a housing (1) which accommodates a cylinder (2) containing a hammer (7) and a piston (3) separated from the hammer (7) by an air cushion (8), a crank (5) connected to the piston and linked with a drive shaft (6) by a counterweight (10) whose center of mass is offset relative to a straight line (A--A) connecting the points of intersection of the axes (O.sub.1 and O.sub.2) of the drive shaft (6) and crank (5) with a plane perpendicular to the axis (O.sub.1) of the drive shaft (6). The projection of the counterweight (10) plotted on this plane is defined by a shape having two portions (12, 13) of which one (12) is symmetrical with the straight line. (A--A) passing through the points of intersection of the axes (O.sub.1 and O.sub.2) of the drive shaft (6) and crank (5) with a plane perpendicular to the axis (O.sub.