Meet the all-terrain wheelchair that’s built like a tank

June 26

A veteran tries a Tankchair for the first time. (Photo courtesy of Brad Soden)

For most of his life, Brad Soden was known to those around him as an army vet, a plumber, a volunteer firefighter and dedicated family man. But that all changed 15 years ago, after a freak car accident left his wife, Liz, paralyzed from the hip down.

Today, Soden is best known as the guy who, through gritty determination, helped her regain a degree of mobility that those who are similarly disabled could have only dreamed of. His invention, the Tankchair, allows her, with the push of a button, to scale stairs and plow roughshod over challenging terrain, such as snow and the shifty sands. And thanks to a motorized caterpillar track system that replaces conventional wheels, it’s perhaps the closest thing to an all-terrain wheelchair.

“People who design wheelchairs generally design them for getting around inside of a building or a home,” Soden says. “For that, they’re great since they don’t damage carpets or flooring, but it also means they want you to basically just exist, but not to live.”

Each custom-built production model costs about $15,000, with many of the parts hand-assembled by Soden himself. Operating out of Phoenix, his delivery method usually consists of hauling them via truck across several states, sometimes to those living as far away as Washington, D.C. So far, he’s sold versions that included a fishing rod as well as one that came with a built-in text-to-speech speaker system for a client who’s vocally-impaired.

(Brad)
This wheelchair, made for a police officer, features a siren and LED Incapacitator. (Brad Soden)

Among his favorites, though, was a recent model fashioned to work like a police car, complete with sirens and a LED “Incapacitator” that disarms suspects by using pulsating light to induce vomiting and other debilitating symptoms. “The best part about building that one,” he adds, “was that it helped the injured client, who was a cop, get back being a cop again.”

At first glance, the concept seems intuitive enough. Continuous tracks, typically found on tanks, bulldozers and other rugged utility vehicles, are engineered so that the load weight can be distributed over the track’s wide surface area. And since larger footprints make for greater traction, the systems have shown to be much better, compared to pneumatic tires, at traversing soft, slippery surfaces that give way, like mud and sleet. They can also ride flat over uneven surfaces, smoothing out bumps along the path. In a convenient world, slapping tank parts onto a chair just seems like the obvious thing to do.

In reality, the Tankchair was the product of relentless tinkering that spanned two years, more than $50,000 in out-of-pocket expenses, a discarded attempt to modify a lawn mower engine, racing tires and, as Soden puts it, “a whole lot of blood, sweat and beer.” For instance, besides identifying which type of wheels would provide ample grip, there was the dilemma of how to build a motor system with enough amps to control it without the risk of setting the rider on fire.

“You don’t want to put a disabled person on something that he may need to run away from when the going gets bad,” he explains.

He eventually settled on using 24-volt electric motors with a one-horsepower output and swapped out the control system’s wiring with ones that were heat-resistant. Next, he hacked the control system so that the right and left motors could be operated independently, allowing the chair to rotate at a pivot. Over time, the clunky contraption that consisted of mixed-and-matched parts from various household items like an A/C unit and audio speaker evolved into a version that boasts lightweight aluminum struts and lithium-ion polymer batteries wrapped in a weather-proof and shock-proof casing.

The Tankchair’s is sold only though Soden’s company Web site, TC Mobility, primarily to disabled veterans, as well as those who may benefit from the outdoor capabilities it offers. Selling the device though governmental assistance programs, such as Medicare, he learned, would require undergoing an extensive approval process with expenditures that sometimes runs in the millions.

“One of things I’d have to do is pay a lot of money to a lab just to test it,” Soden says. “It’s so expensive and such a pain that it’s no wonder there aren’t many start-ups in the medical equipment industry.”

Additionally, he contends that, in the case of wheelchairs, the regulatory system tends to encourage manufacturers to keep production costs low as a way of maximizing profits received through federal reimbursements. A report on Bloomberg Businessweek bolsters Soden’s argument by citing accounting numbers uncovered by the U.S. Department of Health and Human Services that showed Medicare pays as much as “400 percent of what it costs suppliers to make a power chair.”

And so, Soden adds, “it’s because of this old-boy system that you mostly see wheelchairs that are simply junk.”

To make the technology more accessible to the handicapped, Soden has since started the Liz Soden Foundation to donate units to those who can’t afford one. He also plans to eventually switch from subcontracting parts and labor to manufacturing in-house, a move that’s estimated to bring down the asking price to $10,000.

Currently, he’s testing a new model that features a more conventional motorized wheel system, but with a top speed of 30 mph. The Speedster, which he likens to a Ferrari, is designed to be sturdy and efficient enough for urban environments and can be taken indoors without damaging floors. In comparison, the Tankchair, he says, is more like a truck.

“For the longest time, we’ve been used to wheelchairs that limit people,” he says “For me, it’s about changing the way people think about where you can go and what you can do with them.”

Update: An earlier version of the caption and photo credit on the lead image made it appear that Brad Soden was in the image. The caption has been made more clear.

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