By "The Old Yeovilian"
Riding Car bearings should always be ball race types. What kind? Well as you know, the axles move up and down slightly relative to the side frame, even on the most stable of tracks. A single row double sealed race can be strained doing this as it has to be a snug fit in the housing. So a self aligning race will work but at what cost? They are far more expensive than a single row bearing. There is a simple trick to allow a single row bearing to be able to tip with the axle.

Now a bearing is designed to share its load on the outer race of half the circumference. Hence the bore of the race must be accurate.

Bore for the race on a vertical mill. When finished move the table just about 0.03” so that you can take a final cut which in effect elongates the hole. Up or down, it does not matter. This is enough to allow a slight tip, whilst still the load is spread over the diameter.

Now a U.S. supplier of trucks once advocated just drilling an oversize hole. Never ever do this as it puts all of the load on one spot and the balls soon fail.

Does it work? I did this on my riding cars and I use the last car that I made as a control riding car for my train. I figured out that after 23 years the races must be worn. In misplaced financial zeal, I bought eight new bearings. Removing the old ones I could not detect any wear when compared to the new ones. Bummer!

I should have bought one new race for comparisons. I installed the new ones so now the car is good for at least another 23 years plus. (If only I was, too!)

Walt.