Rivian filed to patent a “tank turn” in 2019. Toyota did the same thing in 2020. Ford Authority has discovered that Ford also did the same thing in 2020, a few months after Toyota. In an application published this month that’s called “Methods and apparatus to perform a tank turn,” Ford engineers describe clockwise and counterclockwise tank turns using a vehicle with two electric motors, Ford not yet having any EVs with more than two motors. Rivian, who arguably started all this, showed their tank turn in relation to the quad-motor R1T pickup and R1S SUV, where each wheel could be applied to rotating the truck in place. Rivian hasn’t debuted the feature on its vehicles yet, so it’s possible another maker beats the startup to market.
Ford’s method drives one wheel on each axle, applying the brakes to hold the opposite wheel. To make a clockwise turn, the left front wheel rotates forward, the right rear wheel rotates in reverse, the other two wheels are braked. An airbag suspension is also called into play, to reduce the suspension load on the wheels that turn during the maneuver. You can consider this technique a more complex evolution of the Ford Bronco’s Trail Turn Assist feature that locks up the inside rear wheel during a turn to decrease the turning radius. Adding electric motors and another brake to rotate a vehicle in a skid steer makes Ford’s method, same as Rivian’s, best limited to loose surfaces. The patent explains that the vehicle needs to approve the maneuver.
That’s not all from Ford, either. Another patent application published earlier this month shows a version of the GMC Hummer’s crab walk, but adds the ability for the wheels on each axle to point at one another (extremely toed in) or away from one another (extremely toed out). And there was another patent application for four-wheel steering on a Super Duty that didn’t involve electric motors, just axles with Ackermann geometry. Rotational gymnastics are going to be another battleground for EVs, and Ford’s busy loading ammo.