|
| |
Back
Figure 7-33.—Symmetrical tie-down pattern. | Up
Equipment Operator Basic - Beginning construction equipment operators manual | Next
Dump Trucks |
When securing loads, place the tie-downs in a
symmetrical pattern, as shown in figure 7-33.
A tie-down assembly must have a safe working load
(SWL) of 1 1/2 times the weight of the load to be
restrained. For example, to restrain a crawler tractor
weighing 55,000 pounds, you need a tie-down assembly
for 82,500 pounds (55,000 x 1.5 = 82,500). This means
you need eight 1/2-inch chains with an SWL of 11,000
pounds each and eight binders with 1/2-inch hooks.
On flatbed or lowboy trailers without sides, cargo
must be secured to the trailer to keep it from shifting and
falling off. In closed van trailers, tie-downs can also
prevent cargo from shifting that may affect the handling
of the vehicle. Tie downs must be of the proper type and
strength. The combined strength of all tie-downs must
be strong enough to lift 1 1/2 times the weight of the
piece of cargo tied down.
Chains.— Chains make up most of our tiedown
assemblies. The size of chains normally used in the NCF
is 3/8 and 1/2 inch. They are made of the class A type of
alloy steel. Know the safe working load of any chain
before you put it to use.
Chains used for restraints should have grab hooks
on both ends. Attach the hook into the chain as close as
possible to the tie-downs on the trailer and on the
equipment (fig. 7-34). This prevents the chain from
getting slack once the binder is attached and closed.
Binders.—Binders are chain-tightening devices
that are made of steel with swivels, chain hooks, and a
lever. You hook one of the binder hooks on the chain
near the trailer deck and the other hook higher up the
chain near the load. The chain is tightened by pulling the
lever down, as shown in figure 7-35. A 3-inch-diameter
3-foot-length pipe, commonly known by the term
cheater bar, is normally used on the lever to provide
more leverage when closing the binder.
WARNING
When you are closing and opening the
lever, do not put your head or arm in line with
the lever. If you lose your grip, the lever will
open and hit you.
EQUIPMENT.— Assume the equipment has been
loaded as described earlier in this chapter.
Place your tie-down assemblies to the correct
tie-down on the equipment. Be sure you do not put a
chain around any hydraulic, fuel, or brake lines, because
they will be crushed when the binders are closed. Ensure
you secured all movement symmetrically, as shown in
figure 7-33, so that the equipment cannot move forward,
aft, vertically, or horizontally.
CAUTION
When transporting equipment equipped
with turbochargers, seal off the exhaust stacks
to prevent alterations of the turbocharger
turbine due to wind velocity. Failure to do so
can result in damage to the turbine bearings due
to the lack of lubrication.
OVERSIZE AND OVERWEIGHT LOADS.—
Oversize and overweight loads require special permits.
Figure 7-35.—Using load binders.
7-29
|
