Re: Time Periods for Different Truck Types

Tony Higgins

--- In STMFC@..., Richard Hendrickson <rhendrickson@...>
Thanks for your typically thorough answer. I have the RPCYC issue
with your article and have studied the pictures and text but I'm
still not sure what is meant by the term "spring plankless". What is
a spring plank and what was it's purpose? From your response below,
it seems somehow related to bolster/sideframe alignment and lateral
stability? I can understand why this was a concern but how did spring
planks address it? Can you please elaborate?

Tony Higgins

In the early 1930s all of the truck manufacturers combined forces
improve on the basic ARA design, and what resulted was a self-
spring-plankless design which, though similar in appearance,
began to replace ARA trucks with spring planks (some of the latter
continued to be made through the 1940s, however). Most of the
(incorrectly) so-called Bettendorf trucks in HO scale actually
represent self-aligning spring-plankless ARA-type trucks. Another
improvement for added strength was the double truss side frame in
the lower chords, instead of being U-section, were boxed in and had
shallow strengthening rib extending down onto the spring seat.

Hope this helps.

Richard Hendrickson

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