EE WAS REINSERTING THE CENTER PIN ON THE EQUILIZER BAR OF A CAT D10N. TO DRIVE THE PIN INTO PLACE, HE PARTIALLY INSTALLED THE RETAINING PLATE OVER THE PIN AND WAS STRIKING THE PLATE WITH A SLE DGE HAMMER. AS HE SWUNG THE HAMMER TO STRIKE THE PLATE, THE HAMMER GLANCED OFF A RETAINING PLATE BOLT, STRUCK THE PLATE AT AN ANGLE AND BOUNCED BACK, STRIKING HIM IN THE FACE/MOUTH.