Preventing Metal Fatigue from Ruining Flatbed Trailers

The Nevada Rancher - April 2013

look for can prevent metal fatigue from ending the useful life
of heavy-duty flatbed trailers

When equipment and supplies must be moved on or off-road cost effectively, farms and small businesses depend on heavy-duty flatbed trailers – yet metal fatigue sends many to the scrap mill too soon. The repeated loading and unloading of heavy items, such as tractors, pipe, and farm implements, can strain a trailer’s frame and supports. So can loads brought in from the side, trailer flex from loads coming up the ramp, and stress from driving through fields, ditches, over berms, railroad tracks and rough terrain. If the loads are above a certain threshold, microscopic cracks will begin to form. Eventually a crack will reach a critical
size, and the metal will suddenly fracture. “You’d be surprised at how much metal fatigue occurs if you run standard channel iron or angle iron built trailers at the maximum allowable load,” says Philip McCullough, who was raised on a farm and is now General Manager at Gajeske Inc., a Houston-based distributor of polyethylene pipe, valves, fittings, fabrications and fusion equipment. “If you start seeing microfractures, you have to act quickly or they can turn into a much bigger problem. Previously, we had to retire trailers because they started cracking.”

According to McCullough, when a manufacturer does not support critical areas of the trailer, metal fatigue can develop and “creep” throughout the trailer. As other areas compensate for the metal fatigue, they become
overstressed themselves.

Knowing what to look for in a heavyduty flatbed trailer can prevent metal fatigue and safely, cost-effectively extend its useful life. First, it must be properly engineered to protect the main beam. The flatbed boards
can be replaced, the tires can be replaced, the couplers can be replaced, but if the main beam develops metal fatigue, the trailer will not last. McCullough, who recently purchased six heavy-duty Red Rhino flatbed trailers offered by GoBob Pipe and Steel, a manufacturer of farm and work trailers that meet or exceed
NATM and DOT requirements, identified a number of features that gave him confidence in their reliability and longevity. Given about 50,000 annual miles of use per trailer, McCullough estimates ROI as fast as 18
months on the new flatbed trailers in reduced maintenance-replacement cost and streamlined operations.

“One thing I looked for was a torsion tube under the trailer frame that can take twisting stress from loading and unloading off the main beam,” says McCullough. The Red Rhino torsion tube, made of 4-1/2” OD pipe
running down center of the trailer frame, is tied to the main beam at three points. A second flatbed trailer feature to look for is rectangular steel tubing used in the frame, bumper, and tail lights. The four-sided structural shape of rectangular steel tubing can add strength without much weight, maximizing payload capacity. Yet most trailer manufacturers use channel iron – or worse, angle iron – for side rails, cross-members, and rear bumpers.

“Rectangular steel tubing like GoBob’s tends to disperse stress more evenly with its four sides than channel iron, where the trailer flex is concentrated on a two-sided weld, if the manufacturer welds it at all,” says
McCullough. “Unlike angle iron which tends to rust and accumulate debris, rectangular tubing is stronger and stays cleaner.”

Because the rear bumper is susceptible to impact from the loading tractor and rough ground, it has to be tough. Additionally, it should be positioned to protect taillights from being torn out, particularly in a dovetail
configuration where the lights sit closer to the ground. For added protection, Red Rhino trailer bumpers use the same rectangular steel tubing the frame is constructed from. The taillights, including wiring, are enclosed in frame material and protected by the bumper, to deter the loader or rough ground from knocking them off.
“Unless the loader aims for the taillights, they’re just about impossible to tear up,” says McCullough. “In our low-slung dovetail configuration, our tail lights have drug on rough ground without damage.” To reduce stress when loading and unloading, a reinforced ramp is also important. This can transfer loading weight to the ground and keep additional flexing off of the main beam and structure. Some ramps come standard with adjustable, spring assisted, load equalizers, which can relieve stress on the trailer’s main beam and enable the loading of standalone trailers, unhitched to a truck. This can streamline loading and unloading operations tremendously. Without load equalizers, unequal equipment loading can stress the trailer’s main beams and even lift the rear end of the truck when the load is heavy.

“Look for a reinforced ramp and load equalizers,” says McCullough. “Without them, you get trailer flex from the load coming up the ramp. An unequalized load pushes the trailer down in back and lifts the front, with the weight pivoting on the axles, adding unnecessary stress and metal fatigue.”

“Since we have multiple drivers and trailers, I sometimes need to load a trailer before I have a driver,” adds McCullough. “With the reinforced ramp and load equalizers, I can leave a trailer loaded for the driver, which
streamlines operations. When he gets in, he just backs up, unhooks the old trailer, hooks up the new trailer, and leaves. I don’t pay overtime for staff waiting for the driver to arrive, or to share a forklift. By pre-loading
the trailers, we can save from an hour to half a day in staffing cost.” When Rick Yount, owner of a farm in the
rural greater Sacramento, Calif. area, bought a new flatbed trailer, longevity, customization and value were the issues he focused on.

“If you load an inferior trailer, metal fatigue can get you in trouble quick if it causes you to drop your load,” says Yount, whose previous 20-foot tandem flatbed trailer was not long enough to haul his tractor,
mower, rototiller, scrapers, hydraulic disc, and other equipment and supplies as needed. Yount compared a number of trailers, but found what he was seeking in a 26-foot Red Rhino flatbed trailer with a 6-foot beaver tail ramp.

“At a glance you can tell the GoBob trailer is built to last, and they were willing to customize it at a price that beat 99 percent of the manufacturers I looked at,” concludes Yount. “Under the flatbed, instead of 24 or
18-inch cross bracing, channel iron, and no paint, I got 16-inch centered cross bracing, rectangular steel tubing, and full paint. I got a steel main deck, built long to haul all my implements, and a reinforced 6-foot ramp for easy loading at a gentle angle. My flatbed trailer will last the rest of my life, and then
my son will use it.”

GoBob Pipe and Steel offers a complete selection of flatbed trailers and hay trailers, including a new Red Rhino Hydraulic Dovetail trailer, featuring the unique (patent pending) HydraSled, hydraulic dovetail locking
system. A video of this innovative device can be viewed at
The company can be reached at 1-866-532-9123.


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