EE WAS REMOVING A BRAKE CONVERTER. HE HAD TO REMOVE AN AIR LINE ON THE TOP. HE HAD TO STAND ON THE MUFFLER OF THE TRUCK. WHEN HE WENT TO LOWER HIMSELF DOWN, HE GRABBED THE RESEVOIR & THE CAP C AME OFF IN HIS HAND & HE FELL BACKWARDS ON HIS BACK & HIT HIS HEAD ON THE TRANSMISSION MOUNT.