Abstract: The present invention relates to building and to mining, more particularly o an apparatus for impact action designed for trenchless laying of new underground communications and for reconstruction of existing communications, the apparatus comprising a body, a striker with a through central channel, the striker positioned inside the body with the possibility of performing reciprocal movement, a front chamber formed between the body and striker, a rear chamber formed between the body and the striker, an air distribution system comprising channels for the inlet of compressed air into the chambers and channels for the exhaust of spent air from the chambers, an air conduit, and in which in accordance with the invention the air distribution system is provided autonomously for each of the aforesaid chambers.

Abstract: The machine has a braking arrangement for retaining it against rearward motion and rotation and includes a housing accommodating therein a hammer reciprocable in operation of the machine and adapted to strike the head part of the housing, the latter having a drilling tool rigidly connected thereto. The tail part of the housing supports a sleeve rigidly connected with the braking arrangement. The housing and the sleeve are connected so that the housing is rotatable and axially displaceable relative to the sleeve. The drilling tool rotating mechanism is positioned intermediate the sleeve and the housing and includes a helicoidal couple made up by a helicoidally threaded rod rigidly secured to the housing and a nut, the mechanism further including a freewheeling clutch of which the movable cage is made integral with the nut.