Air Repeater Cars were used to increase efficiency of train air brakes, especially on long trains and during colder weather. These 50’ boxcars include a repeater relay that reads pneumatic signals from the train, and boosts the same signal to the rear section of the train. Southern Pacific® had seven Repeater cars built with roller trucks in the early 1960s, which were numbered #260-266 and used between 1975 and 1977.