Crusher - WikipediaA crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. . Crushing is the process of transferring a force amplified by mechanical advantage through a material made of . The earliest of these were in the foundries, but as coal took hold the larger operations became the coal breakers.coal crushers crushed,Crushers and Equipment Technology in Mining | Crushers .This breaker reduces the coal size by impact and also . resident time for a particle in the crushing chamber and feed size of the.