Side dump trailer wears many hats

FARGO, N.D. – The quest for a more efficient way to transport bulk agricultural products and byproducts often sends farmers to a construction equipment dealer.

The latest crossover from construction to agriculture is the side dump trailer.

There have been concerns over the years about this machine’s inherent instability, but the Jet Company of Iowa said it has solved the problem with its trunnion mounted inverted hydraulic cylinder design.

With previous designs, the six tires opposite the dumping side often bounced a foot or more off the ground, a significant safety issue when handling 25,000 pounds of loaded trailer on rough terrain.

“When we started building side dump trailers years ago, we had the same design as all the others out there,” said Jet manager Ben Nedved.

The conventional design attached the tops of the two hydraulic cylinders to the top of the tub and the bottom end wherever it was convenient on the frame.

Problem area

The geometry between these two pivot points automatically makes the tub accelerate as it dumps. There’s a sudden stop when the tub hits the end of its stroke, and the trailer experiences a big bounce. The potential for accidents was great.

“We finally decided there had to be something safer. We had to come up with a complete new design that would keep the trailer level, with all the tires on the ground at all times,” he said.

“So, we’ve inverted the hydraulic cylinder and mounted one end very low, down within the frame. That allows the cylinder to push on a trunnion at the bottom of the tub instead of the tub top.

“The geometry between the two pivot points reduces tub acceleration. It dumps at a constant speed and there’s no sudden stop or violent bounce at the end of the stroke.”

The new trailer was a hit when Jet introduced it to the construction industry four years ago. Within a year, farmers saw the trailers at work and started buying.

“We find that when we sell one of these to a farmer, all of a sudden he finds all kinds of uses for it,” Nedved said.

“They’re cleaning corrals for neighbors, hauling chicken litter, doing road work. They don’t travel far from the farm for work. We have a lot of these trailers out in North Dakota where there’s lots of road construction and building dikes for flood control.”

Nedved said the tub is rounded steel, made of quarter inch AR400 that is hardened by quenching and tempering for high impact and abrasion resistance.

Unlike other side dumpers, the Jet tub has no centre divider to complicate loading. Corners within the tub are angled to improve load release. The trailer dumps either left or right.

The 34-foot tub carries 21 cubic yards water-full and 31 cubic yards heaping, and is supported by tandem axles.

The 36-foot tub carries 22 cubic yards water-full and 33 cubic yards heaping and is supported by tridem axles. The hydraulic cylinders are five inches in diameter. The system requires 25 to 30 gallons per minute with a pressure of 2,200 to 2,500 pounds per square inch.

For more information, contact Nedved at 515-332-3117 or visit

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