Abstract: Following is disclosed an improved split-type stop ring having two separable body portions forming an annular composite body with passage means useful with a fluid operated, percussion type drill motor for retaining a drill bit and enabling the by-pass of fluid when the bit is suspended above the bottom of a borehole. Fluid by-pass enables the continued flow of fluid to clean the borehole bottom while stopping the otherwise damaging piston-hammer reciprocation when the bit is suspended above bottom.

Abstract: An improved portable peening gun characterized by a pneumatic motor, an axially reciprocable hammer supported to be driven by the motor from an initial position along a linear path, and an improved peening head including an axially reciprocable rod bundle coaxially aligned with the hammer and disposed within the path thereof. The improved head includes a plurality of peening rods, each being characterized by an anvil defined at one end thereof for receiving the hammer in impacting engagement, and a peening surface defined at the other end of a configuration substantially conforming to a segment of a sphere having a radius substantially equal to one-half the thickness of the rod, a barrel for supporting the rod bundle for axial reciprocation, and a helical spring disposed within the barrel for urging the bundle in displacement toward its initial position.

Abstract: An automatic hydraulic hammer including a frame with suitable mountings to attach the frame to an existing hydraulic feed test boring drill machine. A weighted hammer is reciprocal within the frame through a measured distance and is arranged for substantially frictionless operation. A hydraulic cylinder mounts upon the frame and receives its power from the hydraulic test boring drill machine. A plunger is responsive to function of the hydraulic cylinder and terminates downwardly in an arrow-shaped head which releasably connects to a plurality of pivotally mounted clamps. When the head engages the clamps, the hydraulic cylinder is functioned to raise the plunger and the releasably attached hammer through a known distance. The top of the frame is provided with a plurality of depending fingers which function with the clamps to quickly and positively release the head at the top of the hammer travel.

Abstract: A drilling tool assembly comprising an elongated shank having an upper end for receiving driving forces, and having tapered threads at its lower end for engaging a drill head. The shank has first and second downwardly facing shoulders, with one of said shoulders being above the threads and the other shoulder being below the threads. A removable drill head has tapered threads for engaging corresponding shank threads along substantially the full length thereof. The drill head also has first and second upperwardly facing shoulders adapted to respectively bear against the first and second shoulders on the shank. The drill head shoulders are positioned such that they are still separated from the confronting shank shoulders by a gap when the threads of the two elements initially make up along the pitch line during their assembly. The gap optimally falls within the range of about 0.010-0.