PERSON WAS OPERATING A TRACK MOUNTED LOCOMOTIVE AND WAS PULLING CARS OUT OF SWITCH. PERSON WAS STANDING UP IN THE DECK OF LOCOMOTIVE LOOKING BACK TOWARDS CARS HE WAS PULLING OUT AND STRUCK HIS HEAD AGAINST BOTTOM OF OVERCAS. PERSON WENT TO CHIROPRACTOR ON 12-12-02, NOTIFIED OPERATOR ON 12-13-02.