Importance

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Abstract

Rock drilling device comprising a backhammer unit (10) in which a hammer piston (9) is movable to-and-fro for automatically exposing a tube string (4) to impacts in a direction away from a drill bit (8) in the tube string. The backhammer unit comprises a housing (13) and a springloaded tube part (14). The housing and the tube part form between them a first valve (16) and a second valve (17). At drilling the first valve which controls the supply of driving medium to said hammer piston is closed and the second valve which controls the flushing medium flow is open. At backwards feeding of the rock drilling machine (2) along the feed beam (1) with a force which exceeds a predetermined value the first valve is open and the second valve is closed.

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First Claim