How to Tell the Difference Between Thompson Trailer and TC-497 Wheels

Thompson Trailers were unpowered trailers used from 1959 to around 1968. The trailers were towed by the Sno-Train, D8/D9 CATs, and other equipment; they had a load rating of 10-tons. The wheels were built by LeTourneau and 120x48x68 tires by Firestone.

The most significant differentiator between the Thompson Trailer and Overland Train wheels are found in the center of the wheel. The Overland Trains used LeTourneau’s Electric Drive, which used his Tornatorque motor, drivers (gears), and other components. The large circular cap on the Overland Train wheels contains the driver, or gear reduction.

Alaska Freight Lines Sno-Freighter driver. Image courtesy Tim Musgrove

The Thompson Trailer wheels used a large metal cap and nipple.

comparison between the TC-497 wheel and the thompson trailer wheel

There were numerous historical events that caused a mix and match between the Sno-Train, TC-497, and Thompson Trailers. That history are found in detail in my book. For example, if you visit the Sno-Train at the Yukon Transportation Museum in Whitehorse, YT, you will see rims from the Sno-Train and Thompson Trailers.

There are other differences in the two wheel styles above. Can you find them?