Crusher - WikipediaA 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 materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different.characteristic of crusher,Capacities and performance characteristics of jaw crushersHersam (1923) proposed a method for calculating capacities using a Dodge-type jaw crusher. The equation proposed by Hersam includes a number of constants that are only qualitatively related to the machine and material characteristics. These constants in- clude items such as speed, throw, setting. angle between the.