Suction drill unit for dowel anchorage in rock

A suction drill unit for installing an axially extending dowel member (2) into one of rock, concrete, masonry and similar hard materials, said suction drill unit (1) being elongated and having an elongated axis (A) with a leading end (12) and a trailing end, said trailing end forming an insertion end (3) for insertion into a chuck of an at least partially rotating and percussive acting drilling tool, an axially extending tubular shank (7) inserted into and forming at one end the leading end (12) of said suction drill unit (1), said tubular shank (7) having an outside diameter smaller than a diameter of said dowel member (2), a drill bit head (8) mounted on and forming the a leading end of said shank (7), said shank (7) forming a first section of a suction passageway (9) extending axially therethrough in said suction drilling unit to a blank end adjacent said drill bit head (8), a second section of said suction passageway (9) in said suction drill unit (1) forming an axial continuation of the first section of said suction passageway (9) and terminating in a non-rotary suction head (11) mounted on said suction drill unit (1) for suction tight communication with a radially extending opening (10) in the second section of such suction passageway (9) said drill bit head (8) comprises an eccentric leading bit head tip at said leading end (12) having a diameter (B) smaller than a diameter (D) of a hole drilled by said drill bit head (8).