The Morse Brothers (M/B) Jaw Crushers are rugged, heavy duty single toggle jaw crushers for either laboratory use, or continuous small scale production use. The jaw may be adjusted to produce product down to 1/4”, by simple hand wheel adjustment. The jaw and cheek plates are made of heat treated 4140 alloy steel, which has a Brinnell hardness of 460. The jaw plates are corrugated, and reversible, which tend to grab the material and prevent ‘floating’ of the material in the jaw opening. The overhead action provided by the carefully machined eccentric shaft produces a horizontal and downward movement to crush the material, and facilitate choke feeding as well.