EE REPAIRED A FLAT TIRE ON A GRADER LOCATED ON TOP OF HAUL ROAD. AN 18 WHEEL TRUCK WAS HAVING TROUBLE GETTING UP THE ROAD WHERE ANOTHER TRUCK WAS WAITING TO COME DOWN THE ROAD. EE WAS ASKED TO TRY TO HELP PUSH THE COAL TRUCK UP THE HILL. EE POSITIONED THE GRADER BEHIND THE TRUCK. THE CO-WORKER IN THE TRUCK NOTICED THAT THE GRADER WAS MOVING BACKWARDS. EE WAS UNCONSCIOUS BUT CAME TO