is placed between the wheel and the cleat to prevent chafing the tire. The
material is put under the bottom cleat and extended 2 inches above the top
one.
c. Vertical force. A load is subject to vertical force, or bouncing,
to a degree depending upon the roughness of the roadbed. To keep this
bouncing motion to a minimum, wire is used to tie the truck down to the side
stake pockets. To do so, four strands of No. 8gage black annealed wire, or
wire of equivalent strength, are twisted into cables (two cables per wheel),
then run through holes in the vehicle wheel, and finally secured to the
stake pockets. Note item G in figure 2.4.
Other tiedowns are also used to hold down the bouncing motion; note
item E in figure 2.4. They may be located over the axle, spring, or spring
shackles. The tiedowns consist of 1inch 14gage black annealed wire and
pattern 19 anchor plates secured to the floor with eight twentypenny cement
coated nails.
2.5. TRUCK TRACTORSEMITRAILER
Blocking and bracing a lightweight semitrailer with its truck tractor
on a flatcar is not as complicated as you might expect. In fact, you are
already familiar with most of the requirements. To prove this to yourself,
look over the sketch inserted here and try to identify the lettered items.
The space labeled A, of course, refers to brake wheel clearance. Here the
distance exceeds the normal requirement of 12 inches between brake wheel and
load. Since the truck tractorsemitrailer is the total payload on this car,
centering the vehicle's heaviest point in the middle of the car necessarily
moved the truck farther back. The items labeled B, although you can't be
sure from the sketch, are pattern 16 blocks. Other patterns are required
for blocking other kinds of vehicles. The waterproof paper is labeled C;
this is applied after blocks are in place and before
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