a frame,

a drill rod arranged inside the frame and movable in an axial direction thereof, said drill rod including a rear end and a drill counter surface,

a drive arrangement which rotates the drill rod,

a hammering piston of a hammering device by which hammering pulses hammer the rear end of the drill rod in order to transmit hammering pulses through the drill rod,

a movable sleeve arranged around the drill rod and including a sleeve counter surface,

a positioning arrangement which causes movement of the movable sleeve in the axial direction toward the hammering piston so that the sleeve counter surface meets the drill counter surface, whereby the drill rod counter surface on moving away from the sleeve counter surface is movable to a hammer drilling position,

wherein said movable sleeve includes

a ring on which the sleeve counter surface is formed, and

a spring element which is arranged to flex relative to a remainder of the movable sleeve, and

wherein in a non-drilling operation, the sleeve counter surface is arranged to be freely located against the drill counter surface whereby the sleeve counter surface receives hammering pulses from the drill rod which is transmitted to the spring element and the spring element returns the hammering pulses to the drill rod, and

wherein in a drilling operation, the sleeve counter surface is spaced from the drill counter surface so that no hammering pulses are received.