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Time Periods for Different Truck Types

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  • Bob Chaparro
    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
    Message 1 of 1 , Jan 1, 2008
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      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.

      Bob Chaparro
      Moderator
      ==============================

      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
      standard
      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
      were
      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
      which
      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,
      all
      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
      which
      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.

      Richard Hendrickson
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