In the Otto Perry photo above of 3707 it looks like the pilot truck wheels have bearings in the wheel hubs. This was a development by ASF around 1940. I have only seen a couple of then, I think they were not commonly used. A large WP tender one time that was in MW service had to be rerailed. I opened the journal box covers to check the bearings when it was first back on the track. They were 7 X 14 journals, which are huge. When the tender first started to move I could not understand what I was seeing. The tender was moving, but the axle was not turning under the brass. It took me a while to figure out that there was a large roller bearing in the wheel hub and all the rotation was occurring there. It sounded like a good idea, but I doubt the cost justified the benefit.
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