Roller Bearings and the Y6-b

[NW Mailing List]

There's an old saying that goes "there are no dumb questions, only dumb answers."  But I'm afraid I am about to ask a really dumb question.
We all know that the last five Class A locomotives had roller bearings on their main and side rods.  But the Y6-b continued to be built long after the last Class A.  Yet the Y6-b never had roller bearings on the side and main rods.  I assume the reason was because the Class A was a high speed locomotive while the Y6-b, being compound, was a low speed puller.
I'd be interested if any one knows the reason the Y6-b never got the roller bearing treatment.
Bill KingArlington, Virginia
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