Percussive device for driving holes in soil

Abstract

A percussive device comprising a housing with a pointed front end and a hammer piston accommodated in the housing to form a front working chamber therewith. The hammer piston is provided, in the rear portion thereof, with a cavity in permanent communication with a source of compressed air, the cavity serving as a rear working chamber. An airdistribution mechanism includes a tube mounted in the housing within the hammer piston cavity so that it is conjugated with the walls of the cavity, the piston having air passages therein positioned in such a manner that, during the reciprocation, the tube alternately communicates the front working chamber, via these passages, with either the rear working chamber or ambient atmosphere. The device is characterized by the provision of means for controlling the direction of the hole driving constituted by a construction wherein the hammer piston has its center of gravity offset with respect to the longitudinal axis of the housing, the hammer piston hits the housing at a location on a line extending through the center of gravity of the hammer piston, the hammer piston being positively rotatable relative to the housing.