Booster?

I was able to get a cab tour of a CP SD40-2 engine a few months ago and they had an odd air gauge located under the brake handles in the cab that said "Booster". There was also an odd "tank" of some kind in the nose that my guide said had something to with it.

It's a turbo charger air pressue "boost" gauge, the same type you'd see on turbo-equipped automobile and truck motors. CP has them on most of their SD40's. It serves no practical purpose insofar as the Engineer running the locomotive, but can aid in diagnosing a mechanical/performance issue with the diesel engine. The air tank in the short hood has nothing to do with it, the tank(s) in the nose are for operation of the rail sanding equipment. Happy holidays!!!

Well that explains that. Thanks! But as for that tank in the short hood, what sort of sanding equipment is the CP using that requires that tank? It's something that seems to be exclusive to those CP units. Also, what is the plug in the front of the loco marked "Snow Plow"?

CP units don't use any "special" sanding equipment per se, the air tank may have something to do with the CP SD40's being "snoot nose" types. The sand is sprayed on the rail using air pressure, and the tank is the air supply source, fed by Main Reservoir pressure. It acts as a "secondary" air reservoir, that only supplies air to the sanders, without directly using Main Reservoir air to drop sand. Most likely, the CP rail sanding system was an EMD option that CP purchased. The same as optional turbo boost gauges (noted above), seats, air dryers, toilets, air compressors, refrigerators, etc.. CP's General Electric fleet is equipped with an optional "Snow Blaster/Rail Cleaning" system, that has seperate air nozzles to blow high pressure (main reservoir) air onto the rails in order to clean them off, then the standard sand nozzles deposit sand on the clean rails to provide better traction. During winter snow/blizzard conditions, you've got a snow covered rail that would cause a loco to lose traction. Dropping sand into the snow wouldn't do anything, so Engineers can "blast" the snow off the rail, then the sanders drop sand onto the clean rail to aid traction. Options, options, options...

The Snow Plow plug is an electrical outlet, same as in our homes but a different voltage. It's used in snow plow service when a locomotive is pushing an unpowered snow plow such as a Jordan Spreader. An extension cord is run from the plow to that plug, and allows the plow to have electricity to power the radios, headlights, etc..