A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste Viking Penguin,Inc., New York, NY, U.S.A., (1985). pp. 352 (indexed).Dec 20, 2016 . Jaw, Impact, and Cone Crushers for rock, concrete, and more. . USA - HB Notes: Extremely portable, track mounted jaw crusher, equipped.