On Dec 9, 2006, at 6:19 PM, rwitt_2000 wrote:

I don't have that CBC to compare the photos, but according to an
article in Railway Age (April 12, 1924) it describes the use of arch
bar trucks designed by Edwin C. Washburn, assistant to the president
of the B&O. The trucks were placed on new cars ordered in 1922 with
capacities of 40-ton, 55-ton and 70-ton. The class W-1a were rebuilt
by various car builders ~1922 for the B&O so there is a high
probability that the trucks used were of this Washburn design. The
illustrations of the side frame in the RA article appear very similar
to the one in the photo posted by Ben.

Bob, there is a drawing of the Washburn truck side frame in the 1928
Car Builders' Cyclopedia, as well as a photo of a very similar truck
identified as a "Tatum XLT Improved Arch Bar Truck Used on the
Baltimore & Ohio." Neither is the truck shown in Ben Hom's photo.
I'll stick with my original identification of the truck on the W-1a;
it's unmistakably a Pilcher arch bar truck. I will add that the B&O
was well known (one might even say notorious) for its determination
during the 1920s to keep using arch bar trucks of one design or another
at a time when virtually every other RR in North America was converting
to cast steel side frames. None of the improvements that originated in
the B&O's mechanical department overcame the basic weakness of the arch
bar design, which was that the nuts and bolts holding it together
tended to loosen or fail unless the trucks received regular and
frequent preventive maintenance – which, of course, couldn't be assured
on cars that traveled widely off-line in interchange service and might
not come back through the owner's shops for literally years.

Richard Hendrickson