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35
35: An ARA truck with a combination of coil and elliptical
leaf springs. Motion dampening was provided by the
inherent friction of the leaves in the spring. Note that this
particular truck had double-truss side frames, with the
lower chords boxed-in, but was not self-aligning and still
employed a spring plank.
this truck interlocked so that the truck was self-aligning; no
spring plank was required, resulting in a significant reduction
of unsprung weight. Though distinctive in appearance, the
National B-1 truck conformed in all respects to ARA/AAR speci-
fications. Competitive in price and performance, it was widely
adopted by many railroads in the 1930s and 1940s until it was
rendered obsolete by trucks with built-in friction snubbers such
as the Barber S-2 and ASF A-3 (see below).
Coil-elliptic trucks
Several truck manufacturers, notably Gould and Buckeye,
began in the late 1920s to offer ARA/AAR standard trucks with
a combination of coil and elliptic springs (35). The Pennsylvania
Railroad also applied coil-elliptic spring packages to many of its
later ARA type trucks (36). The advantage of this arrangement
was that elliptical leaf springs had inherent friction between
Freight Car Trucks - 14
index contents
MRH-May 2013