--- 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?
In the early 1930s all of the truck manufacturers combined forcesto
improve on the basic ARA design, and what resulted was a self-aligning
spring-plankless design which, though similar in appearance,rapidly
began to replace ARA trucks with spring planks (some of the latterwhich
the lower chords, instead of being U-section, were boxed in and hada
shallow strengthening rib extending down onto the spring seat.