When securing loads, place the tie-downs in asymmetrical 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 berestrained. For example, to restrain a crawler tractorweighing 55,000 pounds, you need a tie-down assemblyfor 82,500 pounds (55,000 x 1.5 = 82,500). This meansyou need eight 1/2-inch chains with an SWL of 11,000pounds each and eight binders with 1/2-inch hooks.On flatbed or lowboy trailers without sides, cargomust be secured to the trailer to keep it from shifting andfalling off. In closed van trailers, tie-downs can alsoprevent cargo from shifting that may affect the handlingof the vehicle. Tie downs must be of the proper type andstrength. The combined strength of all tie-downs mustbe strong enough to lift 1 1/2 times the weight of thepiece of cargo tied down.Chains.— Chains make up most of our tiedownassemblies. The size of chains normally used in the NCFis 3/8 and 1/2 inch. They are made of the class A type ofalloy steel. Know the safe working load of any chainbefore you put it to use.Chains used for restraints should have grab hookson both ends. Attach the hook into the chain as close aspossible to the tie-downs on the trailer and on theequipment (fig. 7-34). This prevents the chain fromgetting slack once the binder is attached and closed.Binders.—Binders are chain-tightening devicesthat are made of steel with swivels, chain hooks, and alever. You hook one of the binder hooks on the chainnear the trailer deck and the other hook higher up thechain near the load. The chain is tightened by pulling thelever down, as shown in figure 7-35. A 3-inch-diameter3-foot-length pipe, commonly known by the termcheater bar, is normally used on the lever to providemore leverage when closing the binder.WARNINGWhen you are closing and opening thelever, do not put your head or arm in line withthe lever. If you lose your grip, the lever willopen and hit you.EQUIPMENT.— Assume the equipment has beenloaded as described earlier in this chapter.Place your tie-down assemblies to the correcttie-down on the equipment. Be sure you do not put achain around any hydraulic, fuel, or brake lines, becausethey will be crushed when the binders are closed. Ensureyou secured all movement symmetrically, as shown infigure 7-33, so that the equipment cannot move forward,aft, vertically, or horizontally.CAUTIONWhen transporting equipment equippedwith turbochargers, seal off the exhaust stacksto prevent alterations of the turbochargerturbine due to wind velocity. Failure to do socan result in damage to the turbine bearings dueto the lack of lubrication.OVERSIZE AND OVERWEIGHT LOADS.—Oversize and overweight loads require special permits.Figure 7-35.—Using load binders.7-29
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