Sandvik Rock Tools, Inc.

Galloway Trust

Faisal J Yousef

Robert F Kane

Joel Ham

David Mildren

Matthew Shofner

Kenneth Ahlhorn

A down-the-hole hammer drill having a reverse circulation system which conducts pressurized air downwardly to a lower cutting face of a drill bit. The air travels across the cutting face and upwardly through a central exhaust passage. The air is conducted to the cutting face through longitudinal and lateral passages in the bit which are kept isolated from the environment surrounding the bit so that no appreciable amount of pressurized air can escape, and so that the passages do not become clogged with dirt. The drill bit comprises upper and lower pieces. Upper sections of the longitudinal passages are formed in the upper piece, and lower sections of the longitudinal passages are formed in the lower piece.

Down-the-hole hammer drill having reverse circulation

A driver sub and a case for enclosing a piston chamber of a percussion drill are threadedly connected by respective identical male and female screw threads. Each of the identical male and female screw threads includes a root portion, the shape of which is defined by portions of two axially overlapping ellipses interconnected by a flat.

Screw thread structure for percussion drill driver sub and case

A percussion drill includes a reciprocating piston surrounded by a cylindrical casing. Disposed at opposite ends of the cylindrical casing are replaceable hollow cylindrical wear sleeves. The wear sleeves are mounted within recesses formed in the outer surface of the casing. Each wear sleeve has a thickness equal to the depth of its respective recess. A longitudinal inner end of each wear sleeve is spaced longitudinally from an end surface of the recess, and a flexible seal is situated between those opposing ends. The wear sleeves can be replaced after being worn by the abrasive environment encountered in the hole being drilled. The wear sleeves may be formed of a more wear resistant material than the casing.

Replaceable wear sleeve for percussion drill

A thread coupling comprises two interconnected screw threads. Each of the screw threads has a root portion shaped as a portion of an ellipse. With respect to one of the threads having such a shape, the major axis of the ellipse is longer than that of the other thread.

Screw thread coupling

A screw thread structure includes a root portion, the shape of which is defined by portions of two axially overlapping ellipses interconnected by a flat.

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Houston, TX, United States of America

Faisal J Yousef