Abstract: Crushing apparatus employs a pair of rotatable crusher drums mounted to rotate about vertical axes to crush material such as mineral ore, fed through a gap between the drums by means such as scraper-chain conveyor. The drums are mounted on pivoting rocker arms which are adjustable to vary the crushing gap. The drums are hollow and are driven in opposite directions by hydraulic drive motors located inside the drums. Conveniently, the hydraulic motors have rotors connected to radial flanges inside the drums and stators fixed to the rocker arms.