Patent ID: 7905343

Claim:
A self-propelled crushing machine having a conveyor belt which travels carrying crushed pieces of an object crushed by a crusher and a magnetic separator belt which is disposed above the conveyor belt and which travels in a direction intersecting the travel direction of the conveyor belt, whereby magnetic material pieces of the crushed pieces of the object are taken off of the conveyor belt, the self-propelled crushing machine comprising: conveyor belt drive means by which the conveyor belt is driven at a conveyor belt velocity in response to a given conveyor belt velocity instruction signal; magnetic separator belt drive means by which the magnetic separator belt is driven at a magnetic separator belt velocity in response to a given magnetic separator belt velocity instruction signal; and belt velocity instruction signal output means for providing a belt velocity instruction signal to the conveyor belt drive means and to the magnetic separator belt drive means, said belt velocity instruction signal being composed of a conveyor belt velocity instruction signal and a magnetic separator belt velocity instruction signal, said conveyor belt velocity instruction signal being provided to the conveyor belt drive means, and said magnetic separator belt velocity instruction signal being provided to the magnetic separator belt drive means; wherein if the conveyor belt velocity in response to a set conveyor belt velocity instruction signal is higher than the magnetic separator belt velocity in response to the magnetic separator belt velocity instruction signal, the belt velocity instruction signal output means makes a change in the belt velocity instruction signal.