Description
During the late 1960’s and early 1970’s the Southern Pacific was looking for ways to solve the problem of their diesels overheating in their many tunnels and snow sheds. They determined that problem was caused by the locomotive’s taking in their own hot exhaust gases while in the confines of the tunnels. The solution came from EMD’s development team which relocated the radiator cooling intakes to the lower portion of the rear of the car body, creating what railfans dubbed the “Tunnel Motor.” This modification allowed the locomotives to take in cooler air that was nearer to the tunnel floor and thus reducing overheating. The Rio Grande was experiencing the same issues and decided to get some Tunnel Motors of their own, ordering some 73 SD40T-2’s in total in 5 separate orders. The last order, #5398-5413 were built in 1980. Features included a 4000 gal fuel tank, nose gyralights, and extended range dynamic brakes with exhaust silencer. The company wanted to order more of them but EMD convinced them to get their new SD50’s instead.
See-through dynamic brake fans
Separately applied wire grab irons
Late Dash-2 cab, front window arrangement per prototype
