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The team at SmithCo works diligently to develop trailer solutions that can help you get more done in a day. That’s why we have developed the industry’s first seven-axle side dump, the SX7.

It Started with a Question

“The idea for a seven-axle trailer started with a question: what is the largest capacity we could have on a single on-road trailer?” says SmithCo sales manager Duane Myears.

That question launched a mission to find the answer. The SmithCo team researched bridge laws and possible truck configurations as well as ways to lower tare weight without compromising structural integrity.

The result? An advanced design that allows operators with a standard commercial license to haul up to 40 tons in a single trailer with easier maneuverability and less upfront cost than doubles or train sets.

40-Ton Hauling in a Single Trailer

The SX7 has a 40-foot tub and 53-foot frame, with a tub design that incorporates three standard axles and four Ridewell steerable lift axle suspensions. The SX7 can comfortably offer a 40-ton hauling capacity in a single trailer without exceeding a 129,000 GVWR with the right truck configuration. To achieve the optimal configuration for each customer, SmithCo provides custom bridge drawings that consider truck weight, axle placement, overall length, and tub placement to maximize the load capacity.

Advantages of a Single Trailer

For long hauls, a single trailer offers many advantages. Upfront costs are lower with a single trailer. A single trailer also translates to greater maneuverability for backing up. Prior to this innovation, achieving a 40-ton haul with side dumps required a train set with a lead trailer, a dolly converter, and a pup trailer. Due to the length of the setup, backing up a train is difficult, if not impossible.

Additionally, hiring drivers for doubles or a train is challenging due to the required Doubles/Triples endorsement. With the SX7 built as a single trailer, a standard Commercial Driver’s License (CDL) meets licensing requirements so there is a larger pool of potential drivers to hire from.

The cylinder placement on SmithCo side dump trailers also offers a distinct advantage. Cylinders are positioned at each end of the tub, rather than in the middle, so the tub can be positioned at any point on the trailer frame. This flexibility is key to achieving the maximum load capacity. This cylinder design also makes the SX series more durable than other side dump trailers on the market.

All of this effort and know-how has resulted in something truly groundbreaking. Says Myears, “When customers see the seven axle trailer, the first thing they say is ‘wow.’”

Want to know more about how the breakthrough SX7 can help you haul more with a single trailer? Get in touch with our knowledgeable sales team, and we can start learning about your specific needs. Give us a call at 800-779-8099 or email us at

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