OPERATOR WAS TRANSPORTING A CATERPILLAR D-11 DOZER WITH TRACTOR AND LOWBOY TRAILER. AS THE OPERATOR STARTED UP A RAMP HE DOWNSHIFTED THE TRACTOR TO 1ST GEAR. THE FRONT TIRES OF THE TRACTOR CAM E OFF THE GROUND AND THE TRACTOR FLIPPED OVER BACKWARD. THE OPERATOR SUSTAINED A BUMP TO THE RIGHT SIDE OF HIS HEAD AND A LACERATION TO HIS RIGHT SHOULDER REQUIRING SUTURES.