Abstract: A percussion drill apparatus is provided which isolates the surfaces that pound on one another from borehole cuttings, while also sealing in grease, all in a compact assembly. The percussion sub which holds the drill bit and which has an anvil surface which can be repeatedly struck, includes a cylindrical outer surface extending down from the anvil surface. The outer barrel, which has a hammer surface that hammers the anvil surface, carries a cage which surrounds the cylindrical surface, and which holds a seal assembly which seals to the cylindrical surface. Thus, percussion occurs in a sealed area.

Abstract: Apparatus which can be utilized on a drilling rig to aid in rotating drill pipe sections to connect and disconnect them, which uses a cat's head chain device to rotate the pipes but which avoids the danger arising when workmen wrap the chain around a pipe. The apparatus includes a jaw assembly which can be installed around a pipe section, and which has teeth on its inner surface to engage the pipe and sprockets on its outside to engage the cat's head chain so the chain can turn the jaw assembly. A stationary frame surrounds the jaw assembly while permitting it to rotate therewithin, the frame also carrying a backup roller to keep the chain engaged with the sprockets of the jaw assembly.

Abstract: A system is described for coating a cylindrical surface of a long thin workpiece by a process which includes flame spray coating that heats the workpiece to a large portion of its melting temperature and which is followed by grinding of the coated cylindrical surface, which produces a final coated surface of more uniform coating thickness than heretofore. The workpiece is rotated about a vertical axis, to avoid slight bending deformation of it, the upper end of the workpiece is allowed to move slightly towards and away from its opposite end, and an upward bias is applied to the chuck device that engages the upper end of the rotating workpiece to avoid column-like buckling of it.

Abstract: A mud pump piston assembly is provided which facilitates replacement and secure holding of piston parts which wear rapidly. A double acting piston includes a piston rod, a pair of hollow piston members on the rod, and a pair of wear rings located between the piston members. The wear rings fit over a flange on the rod and are slightly separated.

Abstract: A mud pump piston assembly is provided which facilitates replacement and secure holding of piston parts which wear rapidly. A hollow piston member which fits on the end of a piston rod to seal against the cylinder, is held in place by a thin pressure ring which is captured by a retainer ring lying in a groove around the piston rod. The piston member has a concave face and the thin pressure ring closely mates with the concave face to support it, while leaving most of the concave face of the piston member uncovered so it can be expanded by pressured mud to more completely seal against the cylinder. In one assembly, the retainer ring is formed with a circular cross section, and lies halfway within a groove of semicircular cross section while the pressure ring is formed of triangular shape and with one side of the triangle abutting the circular retainer ring at substantially the top of the groove.

Abstract: Apparatus which can be utilized on a drilling rig to aid in rotating drill pipe sections to connect and disconnect them, which uses a cat's head chain device to rotate the pipes but which avoids the danger arising when workmen wrap the chain around a pipe. The apparatus includes a jaw assembly which can be installed around a pipe section, and which has teeth on its inner surface to engage the pipe and sprockets on its outside to engage the cat's head chain so the chain can turn the jaw assembly. A stationary frame surrounds the jaw assembly while permitting it to rotate therewithin, the frame also carrying a backup roller to keep the chain engaged with the sprockets of the jaw assembly.