upon the capacity for which the car was designed. The center sill is the backbone of the underframe which is
"boxed-in" by the side and end sills. The remainder of the underframe could be called the ribs, except for the
floor stringers that provide only a mounting place for the car flooring.
The underframe has openings at both ends into which the draft gear is seated. Connected to the draft gear
are the couplers. Both of these pieces of equipment are discussed in the next chapter.