Is the Denza Z9 GT's Crab Walk mode advanced? Not necessarily!

We remember before the 1970s, car makers made their cars bigger, both in size and displacement, for fear that people would say they were small. Later clunk several oil crisis, the road environment is also more and more crowded, the car on the whole became smaller. However, in recent years, with the demand for car purchases and changes in the form of energy, the car is bigger and bigger. Five-metre-long sedan a number of a large number of SUVs, MPVs is a big waist. But the size of the car back, the size of the road can never go back, so cornering, side parking has become a problem. In order to directly hit consumers this pain point, a while ago the listing of the Denza Z9GT crab mode as the focus of publicity for the product point, many less experienced car enthusiasts think that this function is too cool, is the 21st century's greatest automotive invention! But was it really invented in the 21st century? Not necessarily!

The technical core of the Crab Mode is to allow the rear wheels of the car, which can only go straight, to have a steering function. In the 1930s, the American inventor Bruce Walker brought a bold invention, from the video shot at the time can be seen, a Packard from the boot under the outstretched a horizontally placed wheels, the entire rear end of the car up, the two rear wheels hanging after the rear wheels, relying on the lateral movement of the wheels to move the rear of the car out of the narrow parking space, and then retracted and then drive the car out of the car normally. This invention even allowed the car to complete a 360-degree circle, which would have been the earliest rear-wheel steering system, except for the extra third rear wheel.

The same principle appeared in cars even earlier, in 1927, except that instead of rear-wheel steering, the front wheels were oversteered. The structure didn't look like it was built to resist, though, and it felt like it would have to be flattened after a few big ditches and hurdles. However, Walker's invention was not popularised, I guess because the roads were not so narrow at that time, and the demand was not high. And his structure can only be used for parking, but later the re-emergence of rear-wheel steering is not for parking convenience, but handling.

In 1989, the world's first recognised production car with rear-wheel steering appeared: the Honda Disclosure. The coupe was equipped with rear-wheel steering to reduce headway and allow the driver to take corners better. The feature was later seen on the Mazda MX6 GT, Nissan 300Z, and the vaunted GT-R R34.

Honda Disclosure

Mazda MX6 GT

Nissan 300ZX

Nissan GT-R

Come to the last decade or so, Porsche 911, BMW 7 Series, Audi Q7 and many other high-end models are fitted with or optional rear-wheel steering, but the maximum steering angle of the rear wheels of sports cars sedans is relatively small, about 2-3 °, SUVs are relatively larger, can reach 5 °. The working logic is basically in the low-speed domain of the rear wheels and the front wheels reverse rotation, reduce the turning radius, high-speed domain of the same direction to increase stability. Now Denza Z9GT suddenly came up with a crab mode, which is just a low-speed can also let the rear wheels and front wheels in the same direction, in the electronic control is so developed today is actually not a difficult task.

That's how rear-wheel steering technology came about, so if you think I've done a good job, give me a one-two punch, it's important to me. If you want to hear more interesting car stories, leave a message in the comments section, and we'll continue next issue!

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