“Fuel spread all over the place,” recounts Fred McClure, engineering manager of General Engines Co. Inc., which does business as Eager Beaver Trailers in Lake Wales, FL.

“Three or four people were killed—the driver of the tanker, and occupants of several other vehicles in the area. The driver who had the bulldozer on one of our trailers didn’t die. He got out, but his trailer was totally destroyed.”

McClure isn’t sure whether the driver hauling the bulldozer had a wide-load permit, but he insists that’s not the point. “The driver didn’t load the bulldozer properly,” McClure states.

Although such a spectacular tragedy is rare, industry experts interviewed for this article agree that improper loading is all too common and can ruin a trailer quickly.

Overloading
Among the many ways to load a trailer improperly, overloading may be the most widespread—and the most likely to do extreme damage.

“Overloading a trailer will shorten its life or just destroy it,” declares Jim Ladner, national sales manager for Landoll Corp. in Marysville, KS. He tells of a client who purchased a trailer with a 35-ton payload capacity. It broke while hauling a 10-ton load, but some discreet inquiry disclosed that the client previously hauled several 50-ton loads on the trailer, progressively compromising its integrity. “It just happened to have a light load when it broke,” Ladner says.

Triple-L Trailers of Hagerstown, MD, a brand of JLG Industries Inc., makes small trailers for hauling mini-excavators, rollers, skid-steers, small bulldozers, and other compact equipment behind a pickup truck or van.

“Just because our trailer has a 10,000-pound capacity, people try to put their 12,000-pound or 14,000-pound or 15,000-pound machine on it,” says Christian Baillie, the firm’s eastern region sales manager. “This can cause tire damage, axle damage, deck damage, and even structural frame damage. It can be immediate, or it may be seen over time.”

Triple-L builds hydraulic drop-deck trailers that descend to the ground. When they are overloaded, Baillie says, “You may not get the deck up, or over time you will warp the bed and ruin the suspension.”

Sacrificial Ramps
To avoid overloading the trailer you’ve bought, weighing the load against the trailer’s rated capacity is necessary but not sufficient, says David de Poincy, president and chief executive officer of Transcraft Corp. in Anna, IL. “You have to look at the capacity ratings of the entire unit,” he notes.

PHOTO: TRANSCRAFT

De Poincy says Transcraft sells two very versatile drop-deck models to the construction industry. Each has a single drop, center frame, and beavertail ramps designed to haul many types of vehicles, tractors, and construction equipment. “Transcraft’s DTL-2100 model has a beam capacity of 65,000 pounds spread over a 10-foot span when you engage the main beams with dunnage,” he says. “With a tandem-axle trailer, you can haul an evenly distributed load of 80,000 pounds on the lower deck; with a tri-axle trailer, you can haul an evenly distributed load of 100,000 pounds. The DTL-3000 has a beam rating of 80,000 pounds when you engage the main beams with dunnage, and the same evenly distributed ratings on the lower deck as the DTL-2100 model.”

The ramps, however, are rated at 20,000 pounds per axle. “If you have a two-axle vehicle,” de Poincy explains, “you can get 40,000 pounds up there—well within the range of the trailer—but that’s where people get into trouble. Someone has a rubber- or steel-track piece of equipment that weighs 40,000 pounds, he looks at the trailer rated at 65,000 to 100,000 pounds and says he can haul it, but the ramp system is only designed to handle 20,000 pounds per axle. With a tracked vehicle, all 40,000 pounds are engaged on the ramps at one time.

“So now the ramp is bent, and the piece of equipment is up on the deck, and the wheel pans give way. The wheel-pan area [the structure above the tires] is the weak point of the trailer. This is caused by the desire to have a low deck height with a full floor and no exposed tires to get in the way. It restricted the capacity to only a 5,000-pound limit indicated by a label on the side. We have redesigned this section and it now has the same rating as the floor—12,000 to 15,000 pounds—but this guy rolls a 40,000-pound piece of tracked equipment right over the wheels without any dunnage.

“If you place a steel plate or a three-quarter-inch piece of plywood over the wheel pan to engage the main beam, you’ll have no problem whatsoever—but nobody wants to do that. It’s too much trouble. You have to carry that stuff with you, move it around. Instead, they just abuse the trailer and then call for warranty repairs.”

De Poincy describes a DTL-3000 trailer “totally demolished” by a tracked vehicle. “It bent the ramps. Then it crushed the cross-members underneath the deck, so the upper structure had no support and crushed the entire wheel-pan area. There’s only about 3 to 3.5 inches between the bottom of the wheel pan and the top of the tire. If you crush that pan down, you get into your tire and that trailer’s not going to move.”

De Poincy also warns against overloading a trailer’s suspension system. “When you buy a trailer,” he advises, “consider what your heaviest load will be; specify the proper suspension, the number of suspensions needed, and the brakes for that load; and then don’t overload it.” He says that even if the axles can accommodate a heavier weight, the suspension air bags, tires, and brakes with a lower weight rating are likely to fail before the axles’ weight limit is reached.

Loading Over the Side
Loading and unloading from the side of a trailer can lift the wheels on the opposite side entirely off the ground. Even if the trailer doesn’t flip onto its side under the weight of the load, such a maneuver places undue stress on the frame, suspension, axles, wheels, and tires on the weight-bearing side.

“Side loading wrecks trailers and trailer beds,” says Gary A. Knudsen, a salesperson for Towmaster Trailers Inc. in Litchfield, MN. “Generally you can crawl back off once you crawl on, but not safely.”

Side loading usually damages the structural members, says Douglas G. Murray, president of Harley Murray Inc., doing business as Murray Trailers and Murray Trucking in Stockton, CA. “Twisting the outside I-beam rolls the top flange over and starts cracks,” he notes. “Also, when you’re on a trailer with a crawler and you have to spin it around so it’s narrower, it takes out the wood decking.”

Murray says side loading is unavoidable on some occasions, such as a narrow, crooked mountain road where the crawler is off the pavement and the truck driver can’t back up a trailer to load it from the rear. “Another example is a straddle hoe—a piece of equipment used to clean a wide ditch. It’s 20 feet wide and 15 feet front to back, so you load it over the side and haul it sitting sideways,” Murray says.

“Side loading is doable but requires pre-planning. You try to elevate the load to go flat and straight onto the trailer. This means ramps have to be longer, or you need big blocks to get the equipment up in the air.”

The Teeter-Totter Effect
Proper positioning of a load along the length of a trailer is crucial to the integrity and performance of the trailer and the vehicle towing it. “If you put a small, heavy piece of equipment too far forward, you’ll overload the hitch,” Knudsen warns. “The frame members will start to sag or bend. The tow vehicle will have more weight on it than normal, which will affect steering. The front end of the tow vehicle will be too light. It may go straight instead of turning when you want to turn. Eventually, the trailer will start to sway, and then the hitch will break.”

If the load is too far back on the trailer, the axles will carry an abnormally heavy load, shortening their life and the life of the tires on their wheels. The axles and frame could bend. “The trailer will wag like a dog’s tail,” Knudsen says. “The tow vehicle will slide when you hit the brakes. On a small trailer, the electric brakes won’t have enough braking power to stop it.”

PHOTO: TRANSCRAFT

McClure says this problem is less pronounced on lowboys hauled by tractors intended to pull heavy loads. On a properly loaded lowboy, approximately half the trailer’s gross weight should be on the suspension and half on the kingpin, with a margin of safety ranging to one-quarter versus three-quarters in either direction.

With a tow-behind trailer, where the hitch is aft of the rear axle of a towing dump truck or a tractor with a pintle hook, the load point is so far behind the suspension on the tow vehicle that it can act as a cantilever and reduce the load on the front of the tow vehicle. McClure says the suspension on a tow-behind trailer should bear 85% of the trailer’s weight, leaving the other 15% for the hitch.

“If the hitch weight is too high,” he says, “you may almost be able to lift the steering axle in front off the ground. If the hitch weight is too low, you’ll have a fishtailing effect, with the trailer teeter-tottering on its suspension. When the hitch height is too low, you will overload the front axle of the trailer suspension, giving you a squirrelly action and making the front axle brakes perform more aggressively than they need to. The result is excessive wear to the front axle tires and brakes.”

Merle J. Felling, president of Felling Trailers Co. in Sauk Centre, MN, recommends transferring 10% to 25% of the load to the tow vehicle. “If you transfer too much weight to the front,” he cautions, “the trailer is more apt to roll going around a corner, similar to overriding a tricycle. With less than 10% of the weight on the tow vehicle, as you go through dips you end up with a negative tongue load. The trailer will go into a light sway, and then a severe sway that can cause the whole load to go out of control. You could end up in oncoming traffic, or in a ditch.”

Knudsen says a fifth wheel has distinct advantages in load-carrying capacity and the way it stops the vehicle. It can accommodate up to 25% of the load and provides better stopping capability. A fifth wheel allows more weight to be transferred evenly onto the tow vehicle because it is above or ahead of the axle, not 3 or 4 feet behind like a bumper hitch.

Not on the Level
Loading any trailer on a sideslope invites a mishap. Felling, whose firm manufactures tilt-bed trailers, says equipment being loaded on a tilt-bed parked on a non-level surface “has a tendency to drive or slide off the side—especially in winter. We build them for even load distribution. Loading on a slope puts excessive weight on the trailer’s right or left side, which puts undue weight on the side member. The fall-off of equipment amplifies the amount of load that drops down on that side. It can bend or break the frame, depending on how close to maximum load capacity the machine is.”

Many people strive to load a trailer on a level surface, but then don’t ensure that the trailer rides level with the load aboard. “If a loaded trailer is pointed up or down, it will overload one of the axles,” Knudsen warns.

Such an overload makes curb-jumping—a bad practice in its own right—even worse. “Jumping curbs bends one end of one of the axles, usually the front axle on a tandem,” Knudsen says. “You hit an obstruction 6 or 8 inches high, and something’s got to give. Sometimes the impact will cause sagging or bending of the tongue. It could damage the axle and/or the tire, and it could affect the frame.”

Mismatched tongue height is one reason why a loaded trailer may slope. “This is most common when people switch tow vehicles regularly, moving a small trailer from a 1-ton to a three-quarter-ton pickup when they aren’t really interchangeable due to different hitch heights. The more variations in equipment you have, the more potential for a mismatch,” Knudsen says.

Dangerous Detachment
Another good way to ruin a trailer is to load or unload it when it’s not attached to a tow vehicle. “People do it, but it’s highly not recommended,” Knudsen says.

“There’s always a chance of the trailer moving or rolling ahead, or the tongue flipping up. The tow vehicle anchors the tongue and keeps it from moving forward and backward.”

Loading a freestanding trailer also can cause the ramp to flip up, bending the tailboard of the trailer, or to slam down on the landing gear, stressing the jacks so they no longer crank. What’s more, if the loading operation takes place on a hot day or on fresh asphalt, the ramp or landing gear may sink into the pavement, making a mess that results in costly paving repairs.

Buying the Wrong Trailer
Some instances of improper loading are a consequence of buying the wrong trailer for the loads its user intends to haul.

One question to ask, says de Poincy, is whether the trailer will be used just for construction equipment. On certain trailers his firm makes, a hauler could take a machine across the country and bring back a load of gypsum board, lumber, or steel coils to maximize the rig’s profitability—but that’s a different kind of trailer than one designed especially for hauling construction equipment.

“No single trailer is going to do all the jobs out there,” Ladner says. “If the owner of a company is evaluating the purchase of a trailer, the worst thing he can do is not understand specifically what he wants to haul, the capacity of the trailer required to haul his equipment, and the state regulations governing his operation so he can legally transport that load.”