One of the most striking features of the new GMC Hummer EV and the upcoming Chevy Silverado EV is the four-wheel steering, especially the Hummer’s Crab Walk mode. The system allows the vehicle to drive diagonally, which GMC says can help the truck overcome a variety of terrain obstacles. It’s basically a very nice party trick, and apparently one that Ford’s engineers are quite interested in recreating. In fact, patent documents indicate that the Dearborn carmaker wants to expand the system’s capacity within its own off-road vehicle stock.
Documents filed with the U.S. Patent and Trademark Office show that Ford not only sees value in going with crabs, but also in taking concepts like Rivian’s Tank Turn or its own Trail Turn Assist to a whole new level. We’re talking pretty crazy things.
The actual patent document was filed at the end of September 2020, but it was not published until March 31 this year. Entitled “CRAWL OPERATIONS FOR FOUR-WHEEL STEERING VEHICLES”, it features illustrations of a previous generation F-150 Raptor pickup equipped with steering in all four corners. With that said, it looks like this system will only be for electric trucks like the F-150 Lightning. As you can see below, some of the things Ford wants this off-road truck to do is electric driving.
The first thing Ford describes is something bizarre. In a nutshell, it wants to turn the front wheels to the right or left while turning the rear wheels in the opposite direction, and then drive the two axles towards each other. In this way, the car can move left or right on a loose surface without moving forwards or backwards, much like a radiant forklift. If this is a little confusing, the car manufacturer provides illustrations to better explain what it is trying to do.
This type of system could be achieved with any number of powertrains, but it seems that a dual-engine layout is what Ford has in mind. As the flow chart above indicates, this system would work quite seamlessly from the driver’s perspective. The truck would stop, the differentials would lock, the wheels would turn and the car would start moving left / right based on undefined driver entries. Would you turn the steering wheel to move left or right, or press the accelerator pedal? Unclear. However, a gear sensor would ensure that the vehicle remains straight, but modulates the force to the front / rear axle to ensure that this is the case.
Ford does not stop there either. In addition to having a mode for the system that seems to work very similar to the Hummer EV’s Crab Walk, the truck seems to be equipped with steering that is completely disengaged from the steering wheel itself. This allows each of the truck’s wheels to turn independently, which means that while, say, the left front tire is turning to the left, the front right tire can be turned to the right – the same for the rear axle. Thankfully, there are pictures for this as well.
Why would a driver want this? Well, in principle, the patent says that this situation is intended as a kind of last resort to crawl out of trouble. If you’re completely stuck, Ford says a little, “Yeah, sure, why not turn all the wheels against each other to try to get out?” In theory, perhaps this could give the truck just the right amount of traction it needs to free itself. And just like the previous mode, it locks all differentials and uses a gear sensor to make it happen.
The patent further indicates that all of these operations can be performed manually or automatically. However, it is not mentioned that you use them on the sidewalk, to be clear. “Snow, sand, mud, ruts, etc,” are the places where this type of thing will be used, ie a truck potentially equipped with this system will not be able to slide sideways into a parking space. Not without making an awful lot of noise and probably making a number on the truck’s suspension. The document mentions that the wheels will have their own torque sensors to determine the level of traction at each corner, so it will most likely be able to calculate the driver’s intentions. Or, Ford can also just say that using the mode on the sidewalk cancels your warranty, etc.
In any case, I think it’s fair to pop a bottle of champagne and announce that the four-wheel steering war has officially begun. Assuming this system comes on an all-terrain version of the F-150 Lightning, it’s only a matter of time before that truck and the Hummer take off terrain to test their radical capabilities. If you think Rivian’s thinking was extreme, think again, Dearborn might just take things to a whole new level.
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