MECHANIC WAS TRYING TO TAKE A TRACK APART AT THE MASTER LINK. THE MACHINE HAD A DEAD BATTERY AND WOULD NOT START. INSTEAD OF MOVING MACHINE UNTIL MASTER LINK WAS IN POSITION RECOMMENDED IN SERVICE MANUAL, THE MECHANIC STOOD ON TOP OF THE TRACK AND REMOVED THE BOLTS. WHEN HE REMOVED THE LAST BOLT THE TRACK CAME APART AND LAUNCHED HIM OFF OF THE MACHINE.