throughout the length of the car. It contains the couplers and draft gears
in pockets at either end.
b. The body bolsters are transverse members of the car underframe
located over the center of the trucks. Resting on the truck bolsters, they
transmit the weight carried by the center sill to the trucks through the
mated body bolster and truck bolster center plates. The body bolsters
contain side bearings that steady the car and prevent excessive rocking
while it is in motion.
c. The draft gear pockets are the receptacles located at either end of
the center sill that receive the draft gear and couplers. The striking
plates or castings are part of the coupler and draft gear arrangement. The
draft gear is discussed further in paragraph 3.6.
d. Other members required to complete the underframe are side sills,
end sills,. and floor stringers. They provide the tremendous strength
necessary for railway car operation and the mounts for the decking that
carries the load. These members are identified in the inserted sketch.
3.4. TRUCK ASSEMBLY
The wheeled assemblies at each end of the car are called trucks. Each
may have one, two, or more pairs of wheels. Most freight equipment in the
United States has 4wheel trucks. Railway cars and dieselelectric
locomotives use the same type of truck assemblies, discussed in paragraph
2.7. The trucks support the underframe and superstructure; they swivel
enough to ride the rails and negotiate curves readily. An important feature
of these assemblies is that the essential parts most likely to require
repair or replacement are easily reached. A typical freight car truck is
shown in figure 3.2. Study it as you read the following subparagraphs in
which some of the assembly's parts are discussed.