225 ILCS 710/45.16: Bell signals.

The following signals shall be used: one bell, hoist (when engine is at rest); one bell, stop (when engine is in motion); 2 bells, lower; 3 bells, people on cage about to ascend or descend; 4 bells (when shaft sinking is in progress), blasting signals; 9 bells, or flashing of electric lights 9 times in quick succession, danger signal, all people to get out of the mine.