Abstract: A tunneling machine provided with the plurality of impact type cutting tools adapted to be mounted on a rotatable or oscillatable workhead assembly in such order and number that the work done by each of said tools upon angular movement of the workhead is generally equal. The working heads of the tools are mounted in close fit through a circulator disc shaped shield which prevents rock or like particles from passing beyond the workhead area to the bodies of the impact tools. Movement is imparted to the workhead assembly by a plurality of self propelled mechanisms which, along with the workhead, are concentrically surrounded by an enclosed tubular shroud which extends generally the length of the machine and is affixed to the shield.