Abstract: A force-transmitting a drive caps is interposable between a pile driver hammer and a pile to be driven. This cap is formed with an upwardly open cylinder which is of smaller area than the striking face of the hammer. A piston is vertically reciprocal in this cylinder and has an upper surface which is engageable with the striking face of the hammer. The chamber below the piston in the drive cap contains a body of liquid and a body of gas. The gas is pressurized so as to urge the piston into a raised position extending upwardly from the upper face of the drive cap. The piston and hammer are dimensioned so that the hammer first strikes the piston, driving it downwardly in the cylinder, and thereafter strikes the upper surface of the drive cap. The gas body may be held in a separate container within the chamber in te drive cap and the pressure of the gas body is established by the amount of liquid in this chamber.

Abstract: A chamfering apparatus for opposing end faces of a tubular member. The apparatus includes an abutment member capable of advancing toward or being retracted from a line of extension of the longitudinal axis of the tubular material so as to collide with the end face when advanced, a conveyor for transporting the tubular member toward the abutment member, a chuck provided between the abutment member and conveyor for releasably holding the tubular member on the conveyor, and a cutting tool displaceable relative to the end face of the tubular member received by the abutment member and held by the chuck. The cutting tool is capable of rotating around the longitudinal axis of the tubular member.

Abstract: A percussive drill has a bit holder, a percussive drive including a ram slidably mounted in a hollow piston, and a drive transmission for reciprocating the ram in the piston via an air cushion. The forward travel of the ram during percussive action of the drill is limited by a drill bit or an intermediate member interposed between the drill bit and the ram. A member holds the ram in a position further forward, than that attained during the above limited travel allowed the ram, when percussive action is not desired. The holding member is resilient, has a U shaped cross-section, and is entered by the ram as it moves to the further forward position, the ram then forming a seal therewith, and the member also functioning to absorb the energy of an impact by the ram.