Crusher

A crusher comprising:

• a rotatable eccentric shaft having an axis of rotation,
• a main shaft having a portion thereof disposed in a bore in the rotatable eccentric shaft, the main shaft having a central axis which is inclined with respect to the axis of rotation of the eccentric shaft,
• a first crushing head attached to the main shaft and rotatable by the main shaft with respect to a second crushing head so that constrained stroke motion is effected between the first crushing head and the second crushing head such that material can be crushed between the first crushing head and the second crushing head,
• wherein the eccentric shaft comprises an inner eccentric shaft in which the bore is defined and an outer eccentric shaft surrounding the inner eccentric shaft, the inner and outer eccentric shafts being structured and arranged to be continuously rotatable with respect to each other through at least part of a 360-degree revolution, and
• a gear transmission for rotating the inner eccentric shaft and the outer eccentric shaft with respect to each other so as to cause the inclination of the central axis of the main shaft to change with respect to the axis of rotation of the eccentric shaft such that a length of the constrained stroke motion is changed,
• wherein the gear transmission comprises:
• a first cog wheel attached to the inner eccentric shaft,
• a second cog wheel attached to the outer eccentric shaft, and
• a turning mechanism for turning the first cog wheel and the second cog wheel with respect to each other such that the inner eccentric shaft and the outer eccentric shaft turn with respect to each other.