Rivian Patents Bolt-On Low-Range Crawler Gearbox for Off-Road EVs

And when your EV has four motors, you need a low-range gearbox at every corner.

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Rivian Patents Bolt-On Low-Range Crawler Gearbox for Off-Road EVs © Rivian Patents Bolt-On Low-Range Crawler Gearbox for Off-Road EVs

Rivian's electric trucks and SUVs are capable machines. With a motor at every wheel and adjustable long-travel suspension, they can conquer tough terrain, tow with ease, and stay planted in extreme weather. This capability comes at a cost, though. High torque scenarios like rock crawling, heavy-duty towing, and slippery conditions can overheat the motors and limit performance. The answer? A bolt-on low-range gearbox for every corner, of course.

The young electric automaker has just received a patent for such a device, which is the first of its kind as far as we're aware. According to the document, the four gearboxes would mount directly onto the existing drive units and replace the inner CV joints of the stock axles. Inside each gearbox, there would be a planetary gearset to provide the reduction as well as an actuator to engage or disengage low range. The patent states the reduction could be between 1.5:1 and 5.0:1.

Rivian

The units would allow the motors in the drive units to be in a more comfortable operating range to stave off overheating. The gearbox cases would also have provisions for heat exchangers, which would further increase their endurance.

These devices would have to be very sturdy to hold up to the torque the drive units produce, even with hardened gears and heat exchangers. The Rivian R1T has 835 horsepower and 908 pound-feet of torque. It also weighs in the neighborhood of 7,000 pounds. In short, it produces a lot of grunt and it's heavy—even for what it is.

Rivian

Existing 4x4s powered by internal combustion engines often feature low-range gearboxes, but they only need one unit to get the job done. Electric vehicles with multiple drive units often feature no physical interconnectivity between the various motors delivering power to the ground. As a result, more gear reduction units are needed.

I say that like this has been done before. It hasn't. As far as we're aware, no other EV features something like this. If Rivian goes ahead with putting this device into production, it would likely be the first electric vehicle to offer a low-range gearbox. Would that win more diehard off-roaders over to EVs? I think it might.

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