Abstract: A percussive device operable in a forward mode for making a hole in soil and operable in a reverse mode to retract the device from the hole. The device is provided with control means that change the mode of operation alternatively under control of a valve that turns air pressure on and off in a supply or feed line to the device. When the air is turned off from the device the valve establishes connection to an aspirator for establishing a suction condition to the device that will reverse the mode so that upon turning on of air back to the device will make it operate in the changed-over mode.

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.