REVERSAL PERCUSSION DEVICE Russian patent published in 2007 - IPC E02F5/18 

FIELD: mining and construction equipment, particularly to drive pipes and to make holes in ground during trenchless underground service line laying.

SUBSTANCE: device comprises body with stepped inner surface and striker arranged in it so that the striker may reciprocate inside the body. The striker has throttle channel, air inlet and exhaust windows and elastic valve. Body and striker form reverse and direct stroke chambers communicated with air-supply line through connection pipe. Bead with longitudinal grooves communicating reverse stroke chamber with atmosphere is created at rear striker end. Elastic valve is installed on striker between bead and air inlet and exhaust windows. Outer cylindrical surface of elastic valve contacts with inner cylindrical surface of step having lesser diameter as striker is installed in extreme front position. Connection pipe is composed of two stepped sections arranged one over another and performing independent axial movement. Striker contacts with step having greater diameter of said connection pipe sections.

EFFECT: increased impact energy due to extended working stroke of striker.

1 dwg