I was looking through my recently purchased copy of the 1941 Locomotive cyclopedia when I came across and ad from Timken. The ad states that roller bearings can be used on existing steam locmotive driving axles.
Correct me if I am wrong, but I thought that this would require the axles being turned down a bit in diameter so the brearings could fit in the frame jaws. Is this correct? I thought this was how they did a locomotive in Germany recently and the GMSR ex-USATC s-160 #1702. Any information would be greatly appreciated.

david.wilkins@inisightbb.com

> Correct me if I am wrong, but I thought that
> this would require the axles being turned
> down a bit in diameter so the brearings
> could fit in the frame jaws. Is this
> correct?

I don't know about the German engines. GMSR used a variation of a freight car roller bearing, which required a smaller axle diameter fit, as did the pedestals.

Timken engineered driver axle bearing conversions on an individual basis, since locomotives were so different from class to class and road to road.
Generally, conversion to roller bearings on drivers was only done as part of a heavy rebuild/upgrade anyway, and this often involved a change from bar or built-up main frame to a new cast-steel frame or portion thereof as part of the work. The new frame could be cast with the driver pedestals necessary to take the new roller bearings.

Conversion of engine truck, trailing truck and/or tender axles to roller bearings is relatively simple, and has been done on several engines in service today (261, 1522 and 4449 leap to mind, but there are probably many others).

At one time, there was talk of Rowland wanting to convert one of the T-1's to roller bearing drivers, but the cost of the frame modifications necessary was prohibitive. On engines of such size and which run at high speeds, smaller axle diameters is NOT an option.