EE was working on the suction on the operator side of the bolter. Another EE came around from the other side to help. Other EE regained suction behind the boom. EE put his hand up inside of the pre-dump box to clean it out. As he did this, the other EE started the bolter and put down the stab jack which closed the pre-dump door, mashing EE's hand.
U.S. Mine Safety and Health Administration