Bald Tires, No Driveshafts, and Unlimited Ground Clearance: The Hydraulic Rockcrawler You Have to See in Action

When it comes to conquering impossible terrain, most 4x4 enthusiasts understand the fundamental tradeoffs of vehicle design. Long wheelbase for climbing steep obstacles? Short wheelbase for clearing breakovers? Low center of gravity or high ground clearance? These are the compromises that have defined rock crawling for decades - until now.

Enter the “roxDawg,” a hydraulic marvel that’s redefining what’s possible in the off-road world. This isn’t just another rock crawler. Built by Alec Yeager, it’s an engineering masterpiece that solves virtually every limitation traditional rigs face.

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The Hydraulic Game-Changer

What makes this rig so revolutionary is its completely hydraulic system. Instead of a conventional transmission and driveline, the VW 1.9 TDI diesel engine powers a double pump Sawyer Danfoss hydrostat - the kind typically found in heavy-duty skid steers. This hydrostat connects via hydraulic lines to Rexroth variable speed bent axis motors at each axle, eliminating the need for driveshafts entirely.

The hydrostatic drive system doesn’t just provide power - it offers unprecedented control. The rig can perform front and rear digs, overdrive and underdrive both axles simultaneously, and even drive the axles in opposite directions when needed. For hardcore wheelers, this means the ability to finesse through obstacles with surgical precision rather than brute force.

Expandable Frame: The Wheelbase Dilemma Solved

The most mind-blowing feature has to be the variable wheelbase. Four scissor-style slide-out beams integrated into the chassis, powered by massive 48-inch hydraulic rams, allow the wheelbase to extend from a compact 68 inches all the way out to a sprawling 207 inches.

This solves the age-old rock crawler’s dilemma: short wheelbase for maneuverability or long wheelbase for climbing? With roxDawg, the answer is simply “yes” to both. When approaching a vertical climb, the rig extends to place tires at the top and bottom simultaneously. For tight, technical sections, it compresses to a manageable footprint.

Adjustable Everything

Each corner of this beast features an Ori strut mounted to a lever that can be independently raised or lowered by hydraulic rams, providing three feet of clearance travel - not including the travel from the struts themselves. This allows the driver to:

Raise the chassis for extreme clearance
Lower it for stability and center of gravity
Lean side-to-side for optimal weight distribution on off-camber terrain
Manipulate individual corners for maximum traction

The cockpit might look spartan, but it’s pure function over form. A clean dash panel, comfortable PRP seats, and an array of levers and controls give the driver command over every aspect of the vehicle’s geometry. There are no unnecessary panels or floorboards - just open access to all systems.

Pushing Boundaries or Cheating?

Some purists might ask if a rig like this takes the sport out of rock crawling. Is it “cheating” when your vehicle can adapt to any obstacle? The comments section of videos featuring this machine reveals the debate:

“Some people could argue that it takes the sport out of it, but my counter argument would be that engineering something like this is a challenge all in itself,” notes one viewer.

Another adds, “Not cheating. Just creating a new class. Adjusting tires and suspension did the same thing to stock. He just said screw wheel base, ride height and cab angle.”

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The proof is in the performance. In one particularly impressive demonstration, roxDawg tackled a waterfall obstacle that had been made six feet taller by erosion since the previous year. What was already an intimidating climb became seemingly impossible. Yet the rig’s ability to stretch and manipulate its geometry allowed it to conquer the obstacle when conventional vehicles couldn’t even attempt it.

See more of this crazy rig on Alec’s YouTube channel.

The Future of Rock Crawling?

This hydraulic crawler represents the bleeding edge of off-road innovation. While most of us won’t be building anything this complex anytime soon, it showcases what’s possible when creative engineering meets off-road passion.

The mechanical IQ behind this build is nothing short of brilliant. As one commenter put it: “This dude is on another level of genius.” Another joked, “NASA taking notes 👏👏👏👏.”

Whether you see it as the future of rock crawling or a fascinating one-off creation, there’s no denying that roxDawg pushes the boundaries of what we thought possible on the trail. It’s a testament to the innovation that drives our sport forward and a reminder that sometimes the best solution isn’t choosing between competing design priorities - it’s finding a way to have it all.

For wheelers who have spent decades accepting the limitations of fixed geometry, this hydraulic crawler opens up new possibilities. It might not be for everyone, but it certainly makes us wonder: what other “unsolvable” off-road problems might have solutions we haven’t yet imagined?