[Lynn Eades]

Richard, they'd have to be pretty bad, not to last longer than your supply of track.
Al. No personal experience with them. I understand they were used extensively in various types of carrier. (my carrier had RHP strippable semi thrust ball bearings in it)
I think all the manuals have referred to plain bearings, much care required in burnishing them, and in service they were to be replaced by ball bearings.
I think some of the Australian carriers used them, and that some British carriers went to North Africa with them fitted.