Uh, folks, what does ‘tunnel motor’ refer to? I see the term a lot, and still can’t seem to correlate it with anything, including tunnels. I’m sure I’m overlooking the obvious. . . duuuuhhhh.
Thanks.
*DQD: Dumb Question Department: something that nearly everyone seems to understand immediately, except me. . . . 
Information here: http://en.wikipedia.org/wiki/EMD_SD40T-2
Actually had to do with tunnels. Diesels were overheating in tunnels so modifications were done to the units to allow air intake to the radiators from along the deck level instead of normal high position where they would tend to suck in hot exhaust air from other units.
Oh, the only dumb question is the one which remains unasked.
Tunnel Motor: An EMD SD40T-2 or SD45T-2. These engine models have low air intakes with fans mounted beneath the radiators at the rear of the long hood. This enables locomotives to gather cooler air from near track level while passing through tunnels and snowsheds.
FYI, In the upper right gray tool bar of the web page is a “RESOURCES” tab. In the “drop down” window there is “RAILROAD GLOSSARY”.
While I prefer EMD diesels, weren’t many GE diesels made with low or walkway level air intakes by normal course of design or manufactur?
Early GE’s has sort of a ‘mid side’ intake, it wasn’t down at the walkway but it wasn’t up at the top, either. The dynamic brake grids were readily visible on locos so equipped, so a nicer model actually shows this in a similar manner to the now common visible fan blades in the colling fans. The mid-side intakes continued pretty much up til the dash 8 locos. Newer ones have the angled intake under the overhanging ‘wings’ but still have intakes for other stuff down lower.
–Randy