flushing fluid through the drilling tool 9 to the drill hole 14 the rock drilling rig 1 may also include a dust collection system for removing the produced dust from an opening of the drill hole 14 at a front portion 5 a of the feed beam 5 is a suction housing 15 inside which a negative pressure is formed through a suction line 16 the dust is conveyed through the suction line 16 to the carrier 4 where particles are separated from the air the suction housing 15 has a discharge port 17 for connecting the suction line 16 as can be noted the drilling tool 9 passes through the suction housing 15 at a front most end of the feed beam 5 is a contact element 18 by means of which the feed beam 5 is supported to a surface being drilled at least the feed beam 5 and the contact element 18 define a feed beam assembly 19 the rock drilling unit 2 includes a support s for providing support for the tool 9 at the front portion 5 a of the feed beam 5 the support s is located between the contact element 18 and an upper end of the suction housing 16 as it is shown in fig1 if the support is in.