摘要 |
Slacking off device (24) for use on a drilling device (2) for rock drilling. The drilling device (2) comprises a rock drill (4) to which a drill string (10) is adapted to be jointed by means of a thread joint. The drill string (10) comprises an arbitrary number of drill rods (12, 14, 16) which are adapted to be jointed together by means of thread joints. The drilling device (2) comprises a driving device for forward and back rotation of the drill string (10). The slacking off device (24) comprises a clamping device (25) arranged to clamp up the drill string (10) and a separate striking device (33) arranged to strike with an angle towards the longitudinal direction of the drill string (10) of principally 75°-105° on a first (32) of any of said thread joints under back rotation so that an impressed torque on the drill string (10) is obtained in a thread slacking rotation direction to provide slacking of the first thread joint (32).
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