WAS SETTING GATE SHIELDS DURING LONGWALL SET-UP.WHILE ATTEMPTING TO PLACE SHIELDS IN THEIR PROPER POSITION HE HAD HIS RT. HAND ON A RETURN HYDRAULIC LINE. WHEN THE HOSE PRESSURIZED IT MOVED IN HIS HAND AND A STAPLE LOCK IN THE HOSE CONNECTION MOVED IN HIS HAND BETWEEN THE THUMB AND FORE- FINGER.