Live bottoms increase trailer versatility

FARGO, N.D. – Live bottom semitrailers were originally built for asphalt and gravel, but have since found their way into potato and sugar beet operations.

Even on these farms, the number of moving-floor trailers remained small because it was assumed these specialty units could perform a limited number of functions. Most trailer owners stuck by their hopper bottoms, saying it was hard to justify the additional investment for the live bottom option unless there were more opportunities to use the trailers.

“But you have to realize that hopper trailers have limited versatility,” said Gary Hanson of Wilkins Industries in Morris, Minnesota, during the recent Big Iron Farm Show in Fargo, North Dakota.

“A hopper hauls grain and granular and that’s about it. You can’t haul silage or wet byproduct from processing plants. You can’t always find a good backhaul. But if you’ve got a live bottom floor system, you open up a lot of possibilities for making more money with that trailer.”

Live bottom trailers empty their load by mechanically moving the floor surface toward the tailgate. They typically have sloped sides made of a low-friction material that flow down toward the moving floor in the centre alley.

Their use jumped in the United States with the expansion of ethanol and biodiesel production. Live bottom floors are perfect for transporting the wet, soggy byproduct to livestock facilities where it’s incorporated into feed rations.

Winter weather does not pose a problem for unloading wet product. Some ethanol plants run a dozen or more live bottom trailers continually to keep up with input crops and output byproducts.

Once this new use of the trailers became common, it was obvious to beef and dairy producers that live bottom trailers were suitable for hauling silage and manure. Sales of live bottom trailers continued to increase.

If biofuel production increases in Western Canada, it’s seems likely the number of live bottom trailers will also increase in this country.

Although dump style trailers are suitable for carrying the entire range of bulk products, they have been known to tip over when the front of the box lifts skyward.

If a designated dump site is wet from rainfall or if the operator is dumping at a non-prepared site, one side of the trailer can begin to sink. Once the tipping starts, it is impossible to stop.

Overhead power lines also pose a hazard for dump style trailers. These two safety factors have become significant reasons for trailer owners to switch from dump style to live bottoms.

As the use of live bottom floors grew in the U.S., so did the realization that it’s expensive to run these conventional drag chain trailers with their mechanisms exposed to corrosive products. Downtime and maintenance became synonymous with the term live bottom trailer.

The corrosion problem was compounded as many farmers with live bottom trailers sought to spread out their investment by hauling bulk granular fertilizer rather than let the trailer sit empty.

Owners fortunate enough to find contracts for sand, gravel, sawdust and topsoil got away with acceptable downtime and maintenance costs, but those contracts are hard to find.

For the many owners who kept the cash flow going by hauling manure or granular fertilizer, it was a nightmare to keep their rollers and chains running.

Corrosion found its way into every stressed and moving part.

The original system used overlapping flat rubber mats that look like large mud flaps. The mats are pulled toward the back of the trailer by two drive chains below the moving floor. When each mat came to the back of the trailer, it flopped down and dumped its load. It then hung perpendicular from the chain for its trip back to the front of the trailer.

The problem was that corrosive materials easily found their way into everything. Any metal piece that could break did break.

Inevitably, that metal piece busted just as the operator was starting to dump a full load of silage, manure or brewer’s grain. The break was bad enough in good weather, but when it happened at -30 C and the load started freezing to the trailer, it became a crisis.

“Part of the problem is that trailer owners don’t take the time to inspect their chains,” said Dave Thomas of Ti-Brook Trailers in West Fargo, N.D.

“People don’t realize that the old drag chain design places the chain directly below the rubber belt. The entire product load presses down directly on the chain. That creates extra metal fatigue. Put that together with the corrosives the chain is subjected to out in the open like that, and you’re going to have lots of breakdowns.”

The veteran trailer rep said he was called to a farm last year to diagnose a conventional drag chain trailer that had broken its chains several days in a row. He said the owner was understandably frustrated. He was losing money daily on the old trailer.

“When I inspected it, I found over 40 stress cracks in the drag chains,” he said.

“It had obviously not been oiled or inspected for a long time. Each one of those stress cracks could have resulted in another day of downtime. At the worst, he could have been looking at 40 consecutive breaks and 40 consecutive days in the shop if he didn’t replace the bad parts. You can keep those older drag chain trailers running for a long time, but only if you stay on top of the lubrication and keep replacing cracked links regularly.”

The Strong company addressed the problem of the older style double drag chain by adding a third drag chain running down the centre of the rubber mats. This spreads out the load on the chains.

Built by BL Industries in Walhalla, N.D., the chains are powered by an electric or a gas-over-hydraulic motor, which drives through planetary gears.

The undercarriage is kept free of obstructions. The live bottom boxes are also made for tandems. Grain seals are standard equipment and among the options is a manure spreading attachment so the truck can do the field application in dry conditions, rather than download to a manure spreader.

For more information, contact BL Industries at 701-549-3838.

The Trail King live bottom trailers sold by Ti-Brook do not run the drive chains below the belt. Instead, they employ a 47 inch wide continuous rubber belt with protected chains that run along the sides of the belt, where they do not touch corrosive cargo or support the weight of the cargo.

Before the belt and drive mechanism are installed, the entire trailer is given a corrosion-resistant liner.

“Every sq. inch is coated. Every component. We build these with the idea that you can haul any kind of product,” Thomas said.

“Five years ago, we sold 10 units to a corn ethanol company in Nebraska. They’ve been running 24/7 since then, hauling wet ethanol byproduct. That’s probably as much work as a farm trailer would see in 15 or 20 years, but we’ve yet to see a problem with those trailers.”

He said that with more than 7,000 of the continuous belts trailers on the market, there still has not been a broken drive chain. That number includes trailers sold with the hot asphalt option.

The Trail King generally unloads in less than three minutes. The trailer includes a quick-fit tapered grain gate that snaps into the tailgate section so grain and granulars can be easily dumped.

Thomas said the drive system is at the rear of the trailer.

“We use a drive tube instead of a solid shaft to drive the belt. A tube is stronger. With a solid shaft, when you weld, it crystallizes and you get weak spots.”

The drive tube is powered by a hydrostatic motor driving through a double reduction planetary gearbox. Hydraulic pressure requirement is only 3,000 psi, regulated by a 2,500 psi pressure relief valve. Flow requirement is 30 gpm.

Two-inch drive bats are riveted to the underside of the belt. The ends of the bats connect to the chain.

The Trail King live bottom trailer is available in sizes up to 52 feet with a 104 cubic yard capacity. Thomas said a typical ag trailer setup sells for about $70,000.

For more information, contact Dave Thomas at 800-762-5557.

One way to eliminate the chain problem is to eliminate the chain. That’s what the J-Mark Trailer company in Olivia, Minn., decided to do.

J-Mark live bottom trailers use a continuous rubber belt up to 56 inches wide. Rather than relying on steel chain links, the Traction Drive belt is friction driven by a rubber roller.

“The drive is very similar to the head pulley you see on a gravel conveyor,” said J-Mark co-owner Mark Molenaar.

“It’s a hydraulic motor with planetaries and a rubber friction drive wheel that drives the actual product belt – no extra parts between the drive system and the belt. And we use a continuous belt instead of a series of small segments. We have very few parts and therefore less maintenance.

The second big advantage is speed. It takes one minute to unload a 40 foot trailer of silage or wet distiller’s grain from a corn alcohol plant or waste from sugar beets.”

Molenaar said there are no changes needed when switching products. A farmer can haul dry grain the first load of the day, silage the second load, granular fertilizer the third and manure the fourth. The slippery sloped sidewalls are designed for easy cleaning between loads.

The drive system is located behind the landing gear so it puts less stress on the trailer chassis. The drive requires 20 gpm at 2,200 psi. The 40 foot Traction Drive trailer holds 55 cubic yards and sells for $62,000.

J-Mark Traction Drive trailers are available in widths up to 102 inches and lengths up to 48 feet. They are also available with special belts for hot mix asphalt.

For more information, contact Mark Molenaar at 320-579-0447.

Keith Manufacturing has devised the Keith Walking Floor, a running floor with aluminum floor slats that slide on synthetic skid plates. The system can either load or unload a 44 foot trailer in five to eight minutes.

The aluminum slats move only about 12 inches. Then they stop, slide back 12 inches and come forward again.

“People stand for a half hour watching that pallet go to the front of the trailer, then come to the tailgate, then go back to the front, over and over,” Hanson said.

“The natural tendency for everybody is to assume there is some mechanism for raising and lowering the slats as they move from one position to another. But it’s really just a simple friction system. No lifting or lowering involved.”

Hanson said the trailer floor has three distinct sets of moving slats. Each one is connected to a common hydraulic cylinder that moves that slat set forward or backward the pre-set distance.

If the operator pushes the button to unload the trailer, all three sets of slats move one foot toward the tailgate in unison. Friction between the cargo and the three sets of slats cause the cargo to move toward the tailgate and then rest in this new position.

As the slat sets pull back one at a time, friction holds the cargo in its new position. The three slat sets then move forward in unison again, bringing the cargo another foot forward. Then they drop back one by one and repeat the process.

“It works because two sets of slats create more friction than one set,” Hanson said.

“When you have only one set of slats moving, the other two sets hold the cargo in place. Then when all three move at the same time, the cargo moves with them. The only thing the operator has to do is set the control for load or unload.”

He said any product that will put weight on all three sets of slats can be unloaded, including grain, fertilizer, sawdust and potatoes.

“We have a sealed slat option with rubber gaskets so nothing leaks down between the slats. We also have what we call a sweep tarp that some people buy for loose products. As the slats move, it moves the tarp forward or backward.”

The system can be purchased with a hot mix asphalt option.

Because the walking floor extends the full width of the trailer and does not depend on sloped walls it can increase the payload by as much as 20 percent over conventional live bottom trailers.

Hanson said Wilkens buys the walking floor from the Keith factory in Oregon and installs it on aluminum trailers it builds in Minnesota. It requires a wet kit on the truck with a capacity of 30 gpm.

A 45 foot Wilkens aluminum trailer with a Keith Walking Floor sells for $63,000. Hanson said the floor by itself is about a $17,000 option.

For more information, contact Gary Hanson at 320-589-1971.

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