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The right trailer for the job


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June 1, 2012 by David Godkin

They are the low-slung, unsung heroes of the heavy construction industry. Each year ensuring the safe transport of veritable armies of dozers, excavators, loaders and other heavy equipment from yards to work sites across North America. How to be sure the construction trailer you’re looking at is designed and built for maximum productivity and safety depends on the design skills of the manufacturer and the knowledge of the dealer renting or selling it to you.

Do the math

At first glance, flat-bed and low-bed heavy haul trailers are disarmingly simple: your truck cab connects to a removable, hydraulic gooseneck curving down to the front of the deck assembly in behind the truck cab where a series of pins and plates connect or disconnect the cab and trailer deck. Manufacturers may design some of the parts in different ways, but the object is always the same: to ensure safe, smooth loading, transport and unloading of machines upwards of 120,000 lbs.

But is that all there is to a heavy haul trailer? Not on your life, says Russ Losh. The northeast sales rep for Talbert Manufacturing, which specializes in the manufacture and sale of low-bed trailers points to innumerable styles and configurations of axles intended to carry them along. These range from axle extensions to jeep dollies to steer dollies for bridge beams and Schnauble trailers to haul towers for the wind industry. The trick Losh and other trailer experts says is knowing what machine type you’ll be using and what your trailer will likely encounter out there on the road. That fully loaded flat-deck, for example,  “gives you a level surface so you can put just about anything on it,” but it may also cost you many miles of extra travelling distance if it’s over height and has to be routed around a bridge. A popular option for getting as low to the ground as possible is a 4-ft.-wide beam deck.

“A beam trailer is a way to reduce your gross weight as well. Since it is only a pair of beams you don’t have the sides, you don’t have the wood, flooring, you don’t have a lot of things adding weight to your combination. ”

Some contractors prefer a drop side deck over a beam deck. It doesn’t allow you the lower height or weight of a beam deck, Losh says, but it’s easier and quicker to load.

Losh estimates the average contractor will haul between 35 and 75 tonnes of heavy equipment across a range of one or two axles to as many as thirteen axles. Specialty trailers will haul well above 75 tonne depending upon the axle combination at the rear bridge, but also upon state and provincial regulations. Some jurisdictions will not allow four axles, at which point an axle extension providing significant separation distance between the 3rd and 4th axle (e.g. 14 feet) allows you to carry heavier loads. No longer considered a four-axle group, but a three axle and single-axle group, this configuration gives comfort to state and provincial inspectors. “Bridge engineers,” says Losh, “don’t want you concentrating heavy weights in small areas.”

Know where you’re headed

For Chaz Murray, purchasing and sales manager for Murray Trailers in Stockton, Calif. it all comes down to strength: Wheel and tire strength, deck beam strength, pin strength in the goose neck and overall main frame strength. “If the mainframe of the trailer isn’t strong enough you’re going to be scraping the ground as you’re going down the road.” The common denominator for every configuration, however, is what it’s made of. A514 or T1 steel is the metal of choice for manufacturing trailers supporting high machine loads, including the structure members, webs, tie downs and flanges “All the good ones are made out of high tensile T1 steel, not out of lower tensile 50M steel,” says Cory Nakonechny, trailer manager for Custom Truck Sales Inc. in Brandon, Man. 

“The other grades that would be used,” adds Losh, “are 80,000 psi minimum yield; or it could be lower ASTM A8572 strength steel, but the main loading bearing members are usually the T1 material.”

Murray says western US companies mostly run a 16-tire, five-axle grouping (i.e. three axles under the truck and two under the trailer), which allow them to carry up to 92,000 lbs. and enough load strength to haul a 623 scraper or a D8 dozer with relative ease. Adding a jeep dolly on a four frame trailer across a seven-axle configuration will give you up to about 120,000 lbs. of capacity to haul 345 excavators. A 9 axle under a beam deck maxes out at around 180K, a step down trailer around 175K.

Murray estimates a typical 16-tire configuration gives his trailers 25 per cent more capacity than is legally required. That’s important because for most trailer manufacturers and sales staff the fear is not that their trailer won’t hold the load, but that state or provincial regulators think it won’t. One state might allow you to pull a 53-ft.-long trailer and not worry too much about king pin length, for example. Crossing into California on a STAA route using a three-axle trailer more than 48 feet overall with a king pin longer than 40 feet, says Murray, “can get you into big trouble quick.”

State and provincial regulators gear their permitting restrictions to the type of roads that trailers will be travelling over in their region. “If I’m hauling an 80,000 lb. blow case separator, says Nakonechny,I could get away with a tri-axle with a single-axle jeep and a single-axle booster. Or a tri-drive tractor that’ll just make it with tridem low-boy. But everything has to do with where you’re travelling, whether it’s a main R-tech or a secondary municipal road.”

So “know your route,” he adds, whether you’re buying or renting a trailer.  Nakonechny drove heavy haul in the oil patch for eight years before joining the sales staff at Custom Truck thirteen years ago and says some Canadian provinces will allow you “to permit pretty much anything you want as long as you have the right number of axles and the right spread.” It’s all there in your DOT or trucker’s manual, but amazingly some haulers continue to carry equipment weights beyond their trailer’s GVW capacity. “It happens all the time.”

“But these jobs are so critical that most people are getting educated. If this was twenty years ago people would just load the machine on the trailer but nowadays there are so many regulations on height, width and weight they can’t just do that anymore.”

Russ Losh says the bottom line is that mostly regulators want you to carry a machine in the simplest way possible, i.e. one machine per load and within the axle weight limitations of the permit and GVW of the trailer. Many states, he says, will also require you to remove the counterweight on your excavator or the blade from your dozer. Because heavy haulers are paid based on distance travelled rather than weight all this has an obvious impact on your customer. The more that has to be transported separately, the greater the customer’s cost.

Ride easy

The other cost is to the driver or owner operator spending longs days out on the road carrying upwards of 90 tonnes of trailer, truck and machine. Choose a trailer with anything less than a 46,000 pound air ride suspension on that load, says Nakonechny, “and it’s just going to beat up the driver and in the trailer systems. I mean, the trailer’s hopping and bouncing.” His Doepker trailers are outfitted with Hendrickson Intraax suspensions, his Globe heavy haul trailers with Cush suspension, each absorbing about half the impact
from hard road conditions, he estimates. But long-term driver comfort depends on maintaining the suspension’s durability.

“Absolutely. You gotta watch the suspension, especially the wear points in the suspension, like if the rubbers are starting to wear out. They need to be changed out over a certain period of time as do any of the plastics.”

Losh agrees that on suspensions where there’s no welded axle connection the rubber bushings have to be monitored and replaced. That said, most suspensions these days have a lot fewer wear points than they used. “Some manufacturers use an all welded connection to eliminate that maintenance item.” Losh adds that 95 per cent of low-bed trailers produced by a quality manufacturer will be cushioned by an air ride system. “But of course you need maintenance on the air bag system because they eventually wear out, get punctured etc.”

With so much attention paid to keeping costs these days more companies are also turning to lift axles.

“If you’re running both ways loaded it’s really not a big issue,” says Nakonechny, “but if you’re running thousands of kilometers and it’s 50 per cent empty lift axles will save your tires, provide fuel economy.”

A fully loaded trailer also generates tremendous of heat in the braking systems. Naturally, you check for pad wear, cracking in the brake drums etc., but some trailer dealers swear by disc brakes. “They last longer,” says Corey, “and they have better stooping power.” Others are less sure, including Rick Luska vice-president Titan Sales in Burford, Ont. Coming downhill disc brakes perform better, but he believes they last about as long as drum brakes and are more costly. “So we don’t really push people in either direction on those.” Russ Losh agrees. In areas where brakes get a lot of attention by inspectors, e.g. the Rockies “the extra cost isn’t so much of an issue.” Along those flat stretches in the American Midwest or the Canadian prairies “the brakes don’t wear as fast and the costs does become a factor.”

Others complain about the delay between truck brake application and trailer braking, causing one driver to keep his finger on his brake controller when pulling a heavy disc brake trailer because that delay scared him so much. He argues ordinary electric drum brakes work fine as long as the brakes and wiring are in good shape and you have a good brake controller (BrakeSmart or MaxBrake) in your truck.

But whether it’s the size and type of load you’re carrying, state of the brakes, suspension or overall strength and structure, only well informed people can help you with your purchase or rental of a heavy haul trailer. Know your sales staff, says Nakonechny. Ask him about the grades of steel in the trailer he’s flogging. Do they offer hydraulic lifts and if not, why not? And what about the buzz around computerized steering controls that are all the rage in Europe and some gaining traction in North America. A worthy investment?

Nakonechny’s other message is to sales staff themselves and their relationship with the customer.

“You need to know your customer. Because it causes a problem if you’re not in tune with what the customer needs and what they’re planning to do with the trailer.”


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