wrote in message
ups.com...
a pair of circular pipes exists, running in parallel.

I wish to use them as tracks for a small railcar.

where to buy wheels, whose "tread" surface is a semi-circle of the
right size to fit over the pipes? very low speeds in this cargo
application, friction-caused efficiencies should not be an issue.

Or must they be made up by a shop on a custom order?

I don't recall your saying what size the pipes were. As was mentioned by
another poster here, wire rope pulleys are available in that cross-section.
Lighter construction of the same type is available in fibrous rope pulleys.
Some have integral bearings, others are just bushed.

McMaster-Carr carries them in sizes to accommodate up to 1-1/4" rope.

LLoyd