Abstract: A breaker bar or drop hammer principally for breaking large rock into smaller pieces is disclosed. The bar is of a cast heat treatable material, preferably manganese steel, and is of a shape which permits effective heat treatment quenching for adequate strength. Preferred shapes for the one-piece breaker bar are easily cast and avoid thicknesses of over about eight inches in critical areas, so that quenching is effective to avoid deleterious thermal stress cracking and provide a structure of adequate strength.

Abstract: A chain particularly useful for draglines in various type strip mining operations is disclosed. The chain is made up of individual, separately assembled links of generally a U-shape having spaced pin lugs at one end. The lugs have aligned pin eyes for holding a pin between them, which is received generally flush with the outside surfaces of the lugs. To prevent pin rotation and to prevent oblong wear in the pin eyes, the pin and the eyes have a flat surface on the side toward the open end of the U-shaped link. With the pin installed in the eyes, a roll pin is press fit through one lug and through that end of the pin to retain the link pin in place. Openings in the lug are oblong shaped, so that some forward and backward movement of the link pin is permitted and the roll pin is never put in a shear situation. The link units are assembled at 90.degree. to one another, with a pin of one link passing through the next link.

Abstract: A chain particularly useful for draglines in various type strip mining operations is disclosed. The chain is made up of individual, separately assembled links of generally a U-shape having spaced pin lugs at one end. The lugs have aligned pin eyes for holding a pin between them, which is received generally flush with the outside surfaces of the lugs. To prevent pin rotation and to prevent oblong wear in the pin eyes, the pin and the eyes have a flat surface on the side toward the open end of the U-shaped link. With the pin installed in the eyes, a keeper is welded onto the flat surface of the pin, extending between the two lugs to retain the pin in place. The units are assembled at 90.degree. to one another, with a pin of one link passing through the next link. The body of the link may be of a more wear-resistant material than the pin so that the easily replaceable pin wears out first.