Mechanics invent an axle that can achieve steering angles of up to 80 degrees
interestingengineering.com
interestingengineering.com
Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering
ZF's own page about this has a bunch more info https://www.zf.com/products/en/cars/stories/maneuverable.htm...
Their page also contradicts the Interesting Engineering where it said:
"The system further requires an unusually large amount of space in the wheel wells to get that kind of angle, one that can only be achieved in front-wheel drive vehicles."
The ZF page states the opposite:
"EasyTurn is suitable for vehicles with rear-wheel drive, the usual setup in electric cars. And it is ideally suited for volume segments because the MacPherson axle is compatible with around 80 percent of today's common platforms"
If they could pull of an 80deg CV joint, hell even a 60deg one, at a decent price/performance point that would be the real money maker here. Every fork lift made in the last century can turn the wheels near 90, being able to transmit the power there (like you need in a FWD application) is the hard part.
Furthermore, work trucks and vans need this kind of stuff a lot more than compact cars do. A tiny car already turns good enough to be not a pain point in practice, the opposite really. People are already highly satisfied with them so making it turn better is just dick measuring. Taking a van that turns bad and making it turn good is a competitive advantage.
Or just rotate the whole drive with suspension unit, just needs a much larger wheel well.
Imagines upgrading to smart height adjustable suspension by replacing wheel modules.
Though it'd be interesting to see what the aftermarket comes up with and the consequences of that.
This device would gain us 1-2 more cars per parallel parked city block (if it took off). You simply can't get out of a parallel parked space without extra room due to steering angle.
Combine this with auto-park though. Could be nice.
I don’t think that’s very hard as forklifts or any other material- moving equipment don’t have the speed factor constraints so they can use wheel mounted hydraulic or electric motors.
Given that, this whole thing doesn't make any sense to me as a supposed advance. RWD cars have always had tighter turning raidii. Many of them actually have a stop to keep you from turning the wheel 90 degrees such that the tires push instead of roll. I remember adjusting an early 70s Volvo so the front wheel could turn almost 90 degrees just as an experiment, and doing this adjustment was trivial.
RWD car is essentially pushing on a wheel that is almost perpendicular -- not very helpful, a lot of force needed to start the car rolling, potential to damage the wheel. As you get closer to 90 degrees the force needed becomes higher than available traction and the entire thing stops steering at all.
FWD can be thought as "pulling" the car by the front of it, the wheels can be in any position as long as we know how to transfer power.
Most RWD cars mount their engines longitudinally, so the transmission sticks out the back of the engine. This means there isn't a whole lot of "stuff" sticking out to the left and right of the engine. That means more room for wheel articulation.
One problem with FWD is space. Since the engine is usually mounted transversely, the transmission has to go under/beside the engine, taking up space that would otherwise be usable for larger suspension components / wheel articulation.
The other problem with FWD is, as you mention, power transfer. It would be extremely difficult to design a shaft that could transfer power to a wheel that articulates up to 80 degrees. Keep in mind that such a shaft must snake its way through suspension components, too.
If I understand it properly, the demo is using torque-vectoring-by-brake during turns (basically braking the inside drive wheel). Most modern cars can do this, it's just not typically necessary for low-speed turns.
I suspect that the BMW i3 was featured in the video for a lot of reasons:
1) It's RWD, which leaves room for extreme wheel articulation.
2) It's electric, so there's less stuff up front in the first place.
3) The i3's tires are super skinny, meaning less resistance on those super tight turns.
4) The i3's short wheelbase means the outside rear wheel doesn't scrub too badly during tight turns.
Of course, the other posters are right about there being way more space up front in RWD.
Btw, you can achieve the maneuver at 1:20 on FWD by dropping the clutch with the front wheels turned all the way even in conventional range. This slides the car into position at extreme angles. Of course, I don't recommend it due to the wear and tear on the tires, suspension, components, clutch, and the possibility that you don't actually slip the tires and back up into the car behind you, but it is doable, especially in rain / snow.
First thing I noticed as well. I would imagine it's also possible without it, but you'd likely be losing traction on the rear inside wheel? At slow speeds some cars already do this anyway, even with the differential helping minimize it.
The front ratio uses a planetary gear set to give you a higher or lower steering-ratio based on speed, and it allows the stability control to automatically counter-steer a bit when loosing traction at the rear.
Even discounting the parking & u-turn use cases, the amount of extra control you get at the extremes with more steering angle can be pretty remarkable.
It took me a long time to figure out why so many cars in downtown Houston had super fucked up tire arrangements (extreme camber, sticking out really far, etc). Apparently drifting setups are kind of a big deal in the car community now. Makes a lot more sense once you understand the engineering and use cases.
1. People who need negative camber to support high traction while drifting or in tight turns on a race track. (this is the minority unfortunately)
2. Stance kids who think it looks cool and put "most locally hated" stickers on their car and post about it constantly on TikTok. (this is the majority, unfortunately).
There are very few track-driven vehicles running more than -6 degrees of camber in the front, meanwhile it is commonplace to see stance cars with -10 degrees or more of camber. My race car runs -4.5 in the front, as an example, and my buddy's drift car is running -6.
Stance kids and all their variants do things because it looks good to them.
The 'stance' look that you see with people stretching tyres is kind of a throwback to those early days, with a bit more of a focus on form over function. Personally it isn't my thing.
Most small cars with petrol engines have nowhere near enough space for the wheel to turn like that.
Also, if you tried to turn the wheels while at a stop it would cause the wheels to skid. There'd be a lot of friction in general. Ccoordinating the right and left wheels might be complicated enough you'd need to give each wheel its own power steering unit and have drive-by-wire. (Canoo is making a drive-by-wire car, so I guess it's not a regulatory impossibility these days.)
Other drive options include electric hub motors, or just sticking with rear-wheel drive.
"EasyTurn is suitable for vehicles with rear-wheel drive, the usual setup in electric cars."
*The usual setup for luxury/performance electric cars.
Most of the lower end is FWD. The lowest end is all front wheel drive, since they're built on FWD ICE/hybrid chassis, with electric motors put where the ICE used to be. For example, the traction control light in my Fiat 500e rarely turns off. ;)
That's neat it's independent though. I imagine it has a hard time getting stuck, even though I doubt most use it outside the concrete jungle.
https://m.youtube.com/watch?v=QilY00dCof8
This was even 90 degrees
Maybe they have a mechanism that engages the brakes on one of the rear wheels but not the other, causing it to turn? I'm not sure if that would work, and from the last part of the video it looks like one rear wheel is turning forward and the other is turning in reverse.
Alternatively, maybe they have some sort of weird mechanism that locks the drive shaft going to the rear-axle differential (forcing the wheels to turn opposite to each other) and then applies motive force to one of the wheels through an alternate mechanism, like a second drive shaft.
Or maybe it's just some kind of trickery, like they're just pulling the car with a rope that you can't see, or the clips of it accelerating in a circle is a time-reversed clip of it slowing down after being given a big push.
Also, I wonder how they kept the alignment properly, that is a pretty small tolerance affair unless you want to go through a new set every 1000 km or so.
In back you can see a regular axle with a differential, so it's apparently rear-wheel drive. I'm not sure how they get the car to rotate, though... there's probably either some mechanically interesting trick to it, or some clever camera trickery going on.
I think if this is a real thing and not some kind of rigged demo, there's probably something weird about the rear differential or rear drive wheels. Maybe it has an alternate mode where you can't go forward, but the wheels spin in opposite directions when you apply engine torque? I'm not sure what would be the easiest way to do that. Maybe there are two drive shafts, one for forward and one for spinning in place? When the latter of the two is engaged, the "normal" drive shaft is locked in place by a brake forcing the wheels to rotate in equal and opposite directions (due to the differential) and the other drive shaft powers one of the rear wheels somehow.
I don’t think that’s 80° but it’s damned close. That vehicle ceased production sometime around 1979.
That's not exactly how it works, the center of gravity should match up with the kinematic roll center of the axle linkage for there to be zero rolling moment.
"I can make it!"
<thump>
<Narrator>: He didn't make it.
ChrisFix drift car build -How to Install an Angle Kit (Shopping Cart Angle)
No opinion, just want to understand the mechanics of it.
An example would be wheel bearings. They don’t handle pressure from the side very well.
The same applies for a lot of other parts.
[0]https://www.proteanelectric.com/technology/#protean360plus
What about a real product?
Many times when I see people having difficulty parallel parking, it’s because they don’t know when to turn and how much. They end up parked 3 feet from the curb because of their timing errors.
Something like this would make it easier to park in spaces, but it won’t fix of not knowing the steps to parallel park.
But I've started activating the self-parking mode while I park manually, since it forces the backup camera to be turned on at all times. Otherwise it's only on when I'm in reverse.
Doesn't the same apply already with large low-maneuverability vehicles versus subcompacts?
If there's a Ford Excursion or Chevy Suburban overhanging a parallel parking space in to the space in front of it, there's a good chance my Fiesta still fits just fine. If I park there, that's probably going to make it harder for them to leave.
I know in a lot of the world the American city style of parallel parking with defined spaces isn't a thing, you just park along the curb wherever your vehicle fits, but still this situation already exists. Smart cars, those little one seat city runabouts, motorcycles, etc. will fill the tiniest gaps given the opportunity and people still get by.
Seems to be for a few reasons but one is that mass production seems to carry enough compromises that we eventually accept them for long enough to forget how some things were better when volumes were smaller.
The famous get more famous and the less famous get ignored. It’s a really bad spiral that the ones that already have everting are getting all the attention.
> As impressive as the video is, there is no word whether this product is ready for market or not.> London taxis must have a turning circle not greater than 8.535 m (28 ft). One reason for this is the configuration of the famed Savoy Hotel: the hotel entrance's small roundabout meant that vehicles needed the small turning circle in order to navigate it. That requirement became the legally required turning circles for all London cabs, while the custom of a passenger's sitting on the right, behind the driver, provided a reason for the right-hand traffic in Savoy Court, allowing hotel patrons to board and alight from the driver's side.
https://en.wikipedia.org/wiki/Hackney_carriage#Vehicle_desig...
However (there's always a fly in the ointment), we'd need to see how robust it is (front axles take a real beating), and how expensive it is to equip and maintain.
But this... I want this.
The problem of maneuvering vehicles in tight spaces and parallel parking with limited room is a real one that anyone can observe by just standing around in places with heavily occupied streetside parking.
Whether that problem is annoying enough to the right people to be worth the cost of this system is a different matter, but there is definitely no problem searching required here.