I haven't modelled it yet, but Half-Moon has what crews call the Snow Shredder. It's four B units, with the outdside units fitted with roataries, and one-two RDCs sandwhiched in between.
)B-B-RDC-RDC-B-B( )=rotary blade
During travel, the rotary blades are disengaged from drive, and the Outside Bs provide power to get up to track speed. When it's time to play int he snow, the engine is unhooked from the traction motors to spin the blade. The traction motor in the blade unit ( or unit) takes power off the Inside B slug-style to provide muscle for charging the drifts. This works since the name of the game in snow is power, not neccesarily speed. The RDCs provide crew quarters for anyone on shovel duty, or should the unit get stuck. They may not provide any extra oomf to the operation, but by using RDCs, there's no deadweight on the train.
nik .n:
Does the last one blast hot air? Or does it just blow it away?
Looks like the ones used to melt snow off of the switches.