Time Periods for Different Truck Types
- This is a re-post from the Steam Era Freight Car Group. The
information is very useful for those of you who are interested in
achieving more accuracy for you freight car models.
On Jan 1, 2008, at 4:06 PM, Tom Makofski wrote:
> I am looking for a source of information that will give me the
> appropriate freight truck types that were in use from 1900 thru
> 1941. Can anyone help me?
I can give you a quick and dirty answer, Tom. For more detail, see my
article in Railroad Prototype Cyclopedia #4.
By far the largest number of freight cars on the North American
railroads around the turn of the century rolled on one version or
another of the diamond arch bar truck. Typically, turn-of-the-century
arch bars had 5'6" wheelbase, but some shorter wheelbase trucks from
the 19th century were still in service. Arch bars continued to be
applied to new cars, though in diminishing numbers, even into
them1920s, but were banned in interchange in 1941 because their bolted
side frames tended to loosen up and fall apart.
Around the turn of the 20th century some RRs adopted pressed steel
pedestal-journal type trucks, the Fox truck being the most widely used
of several similar designs. But there weren't many of them to start
with and most of those were replaced in the 1920s when it turned out
that the journal boxes were prone to sticking in the pedestal jaws.
Few lasted into the 1930s.
Also around the turn of the century several different types of trucks
with one piece cast steel side frames began to appear. The most common
was the Andrews design with separate bolted-in journal boxes, first
with L-section side frames and later with U-section side frames;
U-section Andrews were applied to all of the thousands of USRA
freight cars built during the World War I period. Less common but
widely used on some RRs were Vulcan trucks, which also had separate
journal boxes bolted in to pedestal jaws; as with the Andrews trucks,
early Vulcans had L-section side frames, later ones U-section. The
first trucks which had journal boxes integral with the side frames
Bettendorf T-section, which also first appears around the turn of the
century and were widely used by some car owners (e.g., NYC, SP/T&NO,
PFE, DL&W). Most of the cars that had them kept them through the
1930s, though they were often replaced after WW II.
Cracking problems at stress points on the Bettendorf T-section side
frames led to the development of U-section side frames in the 1920s,
and at about the same time some trucks initially developed by the
Pennsylvania RR influenced the development of ARA standard trucks
had integral journal boxes and U-section side frames. Similar trucks,
all with spring planks, were made by all of the major truck
manufacturers in the 1920s and '30s, and increasingly they were used
instead of earlier designs on new freight cars. Riding problems, which
became more problematic as car weights and train speeds increased, led
to a search for better riding freight car trucks, and one result was
the Dalman truck, basically an ARA truck with more and softer springs.
Dalman two-level trucks were widely used in the mid-to-late 1920s, and
the Dalman one-level truck enjoyed some brief popularity in the early
1920s. The Pennsylvania RR and some truck manufacturers approached the
problem from a different direction by using a combination of coil and
elliptical leaf springs (the leaf springs being self-damping) in
otherwise standard ARA type trucks. Another development to improve
riding qualities which was widely used in the 1920s and '30s was the
Barber lateral motion device, inserted between the bolsters and
springs, which provided limited self-centering lateral compliance.
The 1930s introduced several more sophisticated truck improvements,
applied to what were otherwise essentially standard ARA designs.
National Type B trucks came along in the early 1930s and were widely
used on some RRs. Later in the decade the Barber Stabilized truck used
spring-loaded friction snubbers to control excessive oscillation. The
same basic principle was later adopted in the ASF A-3 "Ride Control"
truck and in similar trucks made by other manufacturers, but WW II
delayed the introduction of those designs until the mid-1940s.
In the early 1930s all of the truck manufacturers combined forces to
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 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 a
shallow strengthening rib extending down onto the spring seat.
Hope this helps.