question about truss rods and brake wheel staffs - Wrong ques...
1. When were the rules changed so that truss rods alone would not do ? --
requiring steel center sill.
In 1925 the ARA's Arbitration Committee amended Rule 3, section (i) to read:
Cars built new on or after January 1, 1927, will not be accepted from owner
unless equipped with steel underframe having a minimum cross-sectional area
of 24 square inches between the draft stops.
The definition of "steel underframe" as presented within Rule 3 was
clarified by the Committee in 1929:
"The attention of the Arbitration Committee has been called form time to
time to various types of cars purporting to be of steel underframe construction
with request for advice as to whether or not such types of construction meet
the requirements of Rule 3, Section (u), paragraph (1). Your committee's
definition of a steel underframe as contemplated in this requirement of Rule 3,
is an underframe not dependent upon truss rods for support, having steel
center sills with a minimum cross sectional area of 24 square inches, steel body
bolsters and steel cross bearers, suitably tied together. If end or side
sills are used, they must also be of steel.
After that time, truss rods might still have been used for additional
See definition above.
2. At what time were strength requirements for underframes increase to the
extent that the additional support provided by truss rods became irrelevant.
January 1, 1927
West Bend, WI
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do ? --
2. At what time were strength requirements for underframes increaseto the
extent that the additional support provided by truss rods becameirrelevant.
There was another reason for retaining truss rods on cars retrofitted
with steel underframes; the truss rods held the end sills on. In
traditional wood carbuilding, the side, intermediate, and center sills
all had tenons on their ends that fit in mortises cut in the end sill.
The truss rods, running continuously between the two end sills, drew
them together tightly, this keeping the whole frame together. In
retrofits where the wood side and end sills were retained, something
still had to pull the end sills in to keep the wood framing together.
While straight tie rods running parallel to the sills would have
worked, some roads simply chose to retain the original truss rods. The
Soo Line caboose fleet was done like this, with the new steel frames
having queen posts riveted to the steel crossbearers. Thus, one could
still see truss rod cars on the Soo Line in 1970.