The United States of America As Represented by the Secretary of

Bradley V Johnson

Wallace W Roepke

Kelly C Strebig

A method of operating a machine having a constant depth linear cutting head which is retrofitted to a continuous mining machine replacing the rotary head. By altering the usual configuration of the cutting head from the high speed rotating type with a large number of bits, as is currently being used, to one employing a non-rotary type head with 10 percent or less of the usual number of bits, and also operating a combined sumping and shearing action without the bits exiting the coal face being cut, less respirable dust is produced at the mine face. In addition to decreasing the dust and amount of menthane gas - when coal is mined - which is liberated, our method also produces more coal on the average for each cut in the mine face by deeper constant depth cuts in the 3- to 6-inch range by first sumping into the mine face and then shearing the face, without withdrawing or rotating the point attack bits. Sumping may begin near the mine face roof or floor and shearing may be in either a vertical or horizontal direction with or without the aid of high pressure water. One modification calls for shearing with two opposite cutting heads moving towards the mine face center.

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Minneapolis, MN, United States of America

Bradley V Johnson