Westinghouse made a automatic/straight conversion "ring"or"doughnut" that fit between the triple valve and the aux reservoir. A separate straight air brake pipe is run through the train and is connected to this "ring". There is a butterfly check valve in the ring that allows straight air to be applied directly to the brake cylinders. This allows the two completely separate systems to use the same brake cylinders, unlike the D&S' system which requires the retainer valves on each car to be cut out when using the straight air.