Figure 2.6. Use of Idler Car.
The reason for the decreased width is that when a train goes around a curve,
the overhang turns with the car carrying the weight instead of remaining
centered above the idler car. The free end of the load swings toward the
outside of the curve. If the overhang is so wide that it sticks out over
the side of the idler during a turn, it might strike something and cause an
The inserted sketches illustrate what happens; you can see why the
width of overhang must be decreased when the length is increased. Also, you
can see why the load must not be fastened to the idler car; it must be free
to move when the train is going around a curve.
Certain clearances must be observed when using idler cars. The
overhanging portion of a load must be at least 4 inches above any part of
the idler car or its load. Also space on idler cars may be used to load
other materials provided that they are at least 24 inches from the end of
the overhanging load. Clearances are illustrated in figure 2.6. The
uncoupling mechanism between the loadbearing car and the idler car must be
made inoperative though still connected.
Army procedures for loading,
blocking, and bracing equipment
leave nothing to guesswork.
Following the basic AAR rules,
military vehicles and other