Tunnel Motors

[Anonymous]

Was Southern Pacific the only railroad to have tunnel motors? I know they were for air intake in long tunnels (hence the name tunnel motors) but how exactly did they work?

[ericsp]

Cotton Belt and Rio Grande also had them. Of course Cotton Belt was a Southern Pacific subsidiary. Rio Grande Industries (parent of DRGW) later bought SP but they were unaffiliated when they bought the tunnel motors.

They bought them because they were having problems with their SD45s, and possible SD40s with SP, overheating in tunnels and snowsheds. I know SP has places where trains crawl through tunnels and the combination of tunnels and snowsheds made for long enclosed areas.

They have a bigger radiator which allowed the radiators to remove more heat prior to entering the tunnel, which allowed the engine to run cooler and thus spend more time in a tunnel before overheating. If the tunnel gets hot enough, the radiator will not be able to remove heat. While tunnels motors do have the air intakes lower, which would allow them to cool slightly longer in a tunnel than a regular locomotive would. However, I do not know how much of a difference that would make.

There was another thread on this subject a little over a year ago.
http://www.trains.com/community/forum/topic.asp?page=1&TOPIC_ID=36388

[Anonymous]

Ok, that explains it. Sorry about the repeat. [banghead]