end of the car is a brake wheel which is used to operate the handbrake. The
latter is used to hold the car while it is standing still and, sometimes, to
slow it down or stop it when it is moving.
Truck centers are simply the centers of trucks. Because loading rules
make frequent reference to truck centers, it is important to know how to
find them. The center of a fourwheel truck is midway between the two
wheels on the same side of the car or in the middle of the truck bolster. A
sixwheel truck has its center at the axle of the middle wheel on one side
of the car. Placing a chalk mark on the side sill above the truck centers
makes the centers obvious to those doing the loading.
Commercial flatcars do not have standard dimensions but may vary from
one car to another. Still, flatcars commonly used in the United States are
in the 40, 50, or 70ton classnamed for their capacitiesand range from
40 to 60 feet long. All are approximately 9 feet wide. Three of the items
stenciled on the side sill of the flatcar are of particular value to the
shipper: capacity, load limit, and light weight of the car. Of these, load
limit is most important because it states the payload in pounds of the
particular car. Light weight is the weight of the car itself, and capacity
gives the tonnage class of the car.
Because of the limits of tunnels and other obstructions, restrictions
are necessarily placed upon the height and width of loads. It is possible
to specify limits for unrestricted travel on main rail lines in the United
States by citing the lowest overhead and narrowest passage to be found on
any of these lines.
In general, if you know the dimensions and weight of the item you are
shipping and the size and load limit of the flatcar to be used, you can
determine whether the flatcar can accommodate the load and how many of that
item can be transported on a single flatcar.
As you will see in the next section, dimensions and weight alone do
not determine whether a load can be shipped on a particular flatcar.
Special rules and regulations cover clearances around the brake wheel,
location of the load on the car, blocking and bracing the load, and other
essentials, all affecting the transportability of your shipment on a