Third Edition

SECTION 8: GLOSSARY OF RAILROAD AND TANK CAR TERMS
AAR — the Association of American Railroads, a trade
association comprised of North American railroads. The
AAR, among other activities, issues specifications and
rules regarding the interchange of railcars between the
various railroads. The AAR’s requirements for tank cars
are contained in the AAR Manual of Standards and
Recommended Practices (MSRP) C-III, Specification M-
1002.
AAR Specification Tank Car — a tank car built,
altered, or converted in accordance with the tank car
specifications of the Association of American Railroads.
A-end — the end of a railcar, opposite the end equipped
with the hand brake (see B-end.)
Ambient — the temperature and barometric pressure of
the local environment.
B-end — the end of a railcar on which the hand brake is
attached. If both ends of the railcar have a hand brake,
the car will be stenciled “A-END” and “B-END”.
When facing the B-end, the sides of the railcar are
identified as the Right Side and Left Side, respectively.
Body Bolster — the structural members at each end of
a car body that support the car on its truck assemblies.
Bottom Outlet Valve — a valve located in the bottom
of the tank for loading or unloading.
Bottom Washout — a plugged and flanged opening in
the bottom of a tank to facilitate cleaning of a tank car
that does not have a bottom outlet.
Brake Rigging — the assembly of cylinders, levers,
and/or rods under a railcar that provides and transmits
braking action to the wheels.
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