Abstract: A compressed air braking system for a railcar and railcar moving vehicle combination. The railcar moving vehicle comprises a modified semi-tractor configured to ride on railroad track and couple to a railcar, having a conventional pneumatic braking system for braking itself, and a conventional pneumatic trailer brake system for providing compressed air for actuating the brakes of a semi trailer. In accordance with the invention, the brake line connecting the railcar brake system to the railcar brake cylinder is disconnected, and in its place the trailer brake line is connected directly to the brake cylinder of the railcar, whereby the railcar brakes may be actuated independently or in concert with the tractor brakes by an operator of the modified semi-tractor using either the standard brake pedal or a separate trailer brake lever.