SP's Rotary Snowplows were originally built with steam power, but were rebuilt during the 1950's, with the blade being powered by diesel locomotive traction motors.

They get their electrical power from rebuilt F7B units, that were specifically rebuilt to power the Rotaries, and themselves don't have traction motors. The only electrical power the F7B's provide, goes to powering the traction motors that power the Rotary Snowplow blade or wheel. The F7B units are known as 'snails'...

The Rotaries trucks are rigid to help prevent derailments and keep the Rotary Blade at a constant height from the railhead, also the rotaries are chained to their respective 'snail'. Neither the Rotary nor the snail can move by themselves, and rely totally on attendant locomotives to pull or push them.

The Rotaries and 'snails' are part of the Maintenance of Way (MOW) Roster, so carry SPMW numbers, respective snails carry the same number as their Rotary, with the prefix 8. eg, Rotary SPMW 205's snail is numbered SPMW 8205.

For many years the assignments were as follows:

• Sparks, Nevada
  • SPMW 205
  • SPMW 208
• Eugene, Oregon
  • SPMW 206
• Klamath Falls, Oregon
  • SPMW 222
• Roseville, California
  • SPMW 207
  • SPMW 209
  • SPMW 210
  • SPMW 211
  • SPMW 221

There are (at least) two distinct variations with the Rotaries, one has the extension wings, that increase the cut to a 14 foot width, and those without the extensions. The two at Sparks, Nevada (205 and 208) don't have the extensions, while all those at Roseville do. I am not familiar with the two that were? in Oregon, so don't know if they have the extensions or not.

The number of side 'portholes' did vary at one time, some had two, others had three portholes down the sides.

For interior shots visit this website walk through a Southern Pacific Rotary Snowplow

• SP #718
• SP #7202