Abstract: A gyratory crusher includes an anti-spin mechanism which is coupled to a lower end of a main shaft of the crusher and which prevents the main shaft and associated crushing head from spinning when the crusher is not subject to a crushing load. The anti-spin mechanism includes 1) a hydraulic brake, and 2) a gear train which couples the main shaft to the hydraulic brake so as to drive the hydraulic brake to rotate faster than the main shaft while at the same time permitting relative sliding motion between the main shaft and the hydraulic brake without unduly increasing the complexity or height of the crusher. The hydraulic brake is supercharged so as to respond immediately to a tendency of the main shaft to spin. As a result, only relatively low braking forces are required to prevent spinning.