As an apprentice I spent some time in the wheel shop. I can't be absolutely certain, but that machine in the centre of the photo looks like a tread grinding machine - used to re-profile the treads of chilled cast iron wheels - rather than a wheel lathe. Wheel lathes typically have large headstocks and large diameter faceplates at both ends.

As for loco driving wheels, by the 1940s US practice favoured the use of cast steel wheel centres. The preserved UP locos referred to have steel Boxpok wheels. The locos I work on have 69" diameter Boxpoks, which we re-tyred some back in 2003-4. On most locos I've worked on the tyres are not just retained simply by shrink fitting. Older locos with cast iron wheel centres have studs through the wheel rim, and more modern locos with steel wheels use a Gibson ring.

The car wheels in this photo appear to be multiple-wear wrought steel wheels, which were in very widespread use on passenger by 1942. These were one-piece wheels with no separate tyre. They could be machined when worn to restore the tread and flange profile.

The name of this drive that powered the generators off the wheel axle is known as a Spicer drive. It used generally two universal joints, a drive shaft, and a large generator to charge the onboard batteries, normally 32V. The Spicer drive only effectively charged the batteries at road speed.

According to Amtrak's Standard Maintenance Procedure or SMP revised 3-4-2011, "Effective January 1, 2015, use of an axle drive for a generator system (either Spicer or belt) is prohibited at the time of the car's next PC-1 annual inspection, and the drive apparatus must be removed from the axle by that time."

So if you see one, get a photo of it as they will become more rare to see in operation!

While visiting the U.P. Yard in Cheyenne I spied a flat car, tarp covered,
with a huge load upon it as the car was bent under the weight. The worker
told me it was a wheel lathe as this rail road maintains gorgeous steam
2-6-6-2's that are used.
The wheels on the engines and cars are of cast iron to which a steel "tire" with
flange must be shrunk fitted. Can you imagine turning an 80" locomotive
wheel so it is within .001" round? When the wheel is finished a steel "tire"
is then fitted by heating the steel disk so it expands over the wheel and locks
solid when cool... a very hard and precise job indeed!
One of Jack Delano's photos show a roaring hot tire just fitted.... take a look
by searching for: "Wheel of Fire".

These look like freight car wheels, or non-powered locomotive wheels... they don't have the gear or traction motor that powered wheels would have. (Yes, there were diesel-electric locomotives in and before WWII. Just not very many.)

The wheelset to the right of the man standing, with the gearbox-looking thing in the middle of the axle and a pile of small parts on the floor in front of it, might be designed to drive an under-car generator. Before locomotives provided electricity to the train, some passenger cars were lit by generators turned by their own wheels - sort of like a giant bicycle headlight. Each car would have its own generator, and batteries for use while in the station.

I think the big machine with the electric motor on top is a wheel lathe. Railroad wheels are made with a certain taper to the "tread"; this makes the train car center itself between the rails and go around curves smoothly. After a while, the wheels wear down, and the train car will track badly; one fix is to re-machine the tread back to the proper taper, which is what a wheel lathe is for.

There are a few standard wheelset sizes for freight cars, so a lot of railroads keep a supply of new or rebuilt wheelsets (the assembly of two wheels and an axle) at big freight yards. If a car needs new wheels, they hoist it up with jacks or a crane and swap the wheelsets - the old wheelsets go on top of a flat car. When the flat car is full, it goes to a shop like this, so all the wheelsets can be inspected for cracks and re-machined in batches. Cracked wheels and axles, and wheels that have worn so much that they can't be re-machined, are sold for scrap; often they are melted down and cast back into new railroad wheels.

Powered axles have a traction motor in the middle. Sometimes these are swapped out complete just like non-powered axles, but sometimes the wheels are re-machined on the car. There are wheel lathes that sit in a pit under the tracks; the train car is driven over the pit, a small section of the track is removed, and the lathe can machine the wheels while they are still installed.

The trolley crane, with exposed conductor rails, is a nice touch. These days, there would probably be a long insulated cable feeding this crane. Really big cranes (enough to lift an entire locomotive with) still have busbars like this, but they're buried under a lot of insulation.

JD was really a master at composing gorgeous photographs of quotidian subjects and this is no exception. What serendipity to have an arrow on the floor.

This is not a locomotive shop. It is a wheel shop and there are wheels from freight and passenger cars present. The wheelset under the hoist is a passenger car set. The gearbox between the wheels drives a generator which charges batteries for the car electric system. Wheels need to be reprofiled due to wear or flat spots.