Know the Ropes

| December 12, 2008

Freight that is secure puts the owner-operator at ease, knowing the cargo is safe, his rig is not at risk, and there is no fear of an out-of-service violation from inspectors.

The problem with dry van securement, the Federal Motor Carrier Safety Administration recently ruled, is not that cargo restraining devices – trailer tie-down points, cargo straps, load locks, jack bars, shoring beams and chock blocks – are ineffective. The problem is that truckers use them incorrectly or don’t use enough of them.

Properly secured freight won’t shift, unbalance the trailer and cause an accident. It won’t be damaged in transit and raise liability questions. Freight that is secure puts the owner-operator at ease, knowing the cargo is safe, his rig is not at risk, and there is no fear of an out-of-service violation from inspectors.

“When you leave something in there loose and let it roll around, it can have a lot of impact,” says Rod Ehrlich, chief technology officer with Wabash National Trailer. When freight moves, it builds force and can damage trailer walls. But if it’s immobilized against a bulkhead, the force created by the truck’s movement will have no effect.

Even trailers without the strongest walls withstand up to 18,000 pounds of steady pressure in testing, Ehrlich says. “In all van trailers, that wall is fairly substantial when it comes to load confinement,” he says. “The DOT is well aware of that, and they don’t have a problem with shoring a load against the wall.”

“The load restraint for dry vans is unlike the flatbed system, in which you must have tie-downs to ensure the load does not fall or blow off the trailer,” says Ralph Abato, national sales manager of Ancra Cargo Securing Systems in Cincinnati. “The trailer walls act as containment. All the driver has to do is immobilize the load so it won’t tip, shift or spill.”

Suitable restraints are available for any dry van freight. Straps and some rigid restraints generally work in tandem with tracking attached to interior bulkheads. If the ends of the restraint lock securely into the track, a working load limit can be assigned the restraint. Safe securement requires knowing the limits of the restraints and the weight of the cargo.

Generally, working load limits of straps are a third of breaking strengths. A strap with a 1,500-pound breaking strength will have a working load limit of 500 pounds. When combining restraints such as straps, beams or load locks, make sure the sum of their working load limits is equal to or greater than half the weight of the cargo. For example, four cargo straps each rated at 500 pounds could legally be used to secure no more than 4,000 pounds of freight, according to regulations.

Also, make sure cargo restraints are free of defects. “If it’s a required tie-down and if it has a knot, that’s an out-of-service violation,” says Collin Mooney, director of training programs at the Commercial Vehicle Safety Alliance. “A knot gives it a weak point.”

Here are some common, proven devices for keeping a load in place.

LOAD LOCKS or cargo bars are the most common restraints because they’re inexpensive and versatile. They work on friction created when their rubber “feet” press against the trailer. Most consist of two metal tubes that slide freely, like a telescope, to adjust overall length and a lever-operated ratchet for small adjustments and locking the device into position. Newer models break down into two or three pieces, making storage easier.

Drawbacks: Because trailer walls vary, load locks can’t be strength rated, and they’re generally useful for only very light cargo. Also, some plate trailer walls are designed to flex; load locks just force them apart without providing much securement.

JACK BARS work much the same as load locks, but they are generally square, made of much stronger metal and have much bigger “feet.”

Comments are closed.