THE EMPLOYEE WAS TRAINING A CO-WORKER ON A HAUL TRUCK. AS THEY WERE POSITIONING THE TRUCK TO DUMP A LOAD, HE STEPPED OUT OF THE TRUCK CAB IN ORDER TO GIVE THE TRAINEE A BETTER VIEW. NOT REALIZ ING HE HAD STEPPED OUT, THE TRAINEE AS HE POSITIONED HIS TRUCK PINNED THE EMPLOYEE BETWEEN TRUCK & RIB. HE WAS TRANSPORTED TO THE ER. THERE WERE NO FRACTURES AND HE WAS RELEASED TO LIGHT DUTY