Reversible, percussive device for ground perforation

Abstract

A reversible ground perforating device powered by a gaseous medium under ssure, comprising a hollow cylindrical body with a pointed front end. The body accommodates a hammer adapted to reciprocate therein. A front power chamber of variable volume is formed by the hammer in the body. The rear end of the hammer has a cylindrical hollow which forms a rear power chamber of variable volume. The power chambers are interconnected by means of ports provided in the hammer. A stepped cylindrical barrel is located inside the cylindrical hollow in the hammer and coaxially therewith. The barrel is secured in the rear end of the body and the large-diameter portion of the barrel is arranged to interact with the hammer. The wall of the large-diameter portion of the barrel has ports. A spring-loaded stepped sleeve is mounted coaxially with the stepped barrel so that the large-diameter portion of the sleeve is adapted to cover the ports in the barrel. The space between the large-diameter portions of the sleeve and barrel forms an annular chamber. Holes are provided in the sleeve small-diameter portion interacting with the barrel small-diameter portion. A ring is flexedly mounted in the large-diameter portion of the barrel in the front end thereof and coaxially therewith. The space between the ring, the inner surface of the barrel and the outer surface of the sleeve forms an auxiliary annular chamber. The annular chamber is in communication with the source of a compressed gaseous medium during forward movement of the ground perforating device, whereas the auxiliary annular chamber is in communication with this source during reverse movement of the device.