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"
Considering a) ze German penchant for interesting control linkages and b) the lack of an 80degree CV shaft shown in the demo video I'm assuming this is a RWD thing.
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.
A lot of commercial operations (including usps actually) take a 'just dont ever reverse anytime anywhere' approach with their drivers to reduce accidents. I could definitely see this being hugely popular on work trucks and vans.
The issue is that there is a lot of other things that you have to consider when designing linkages. You have to make sure the system is directionally stable, and works with suspension. On forklifts, you don't really need to design for that.
Maybe the thing to solve this will be individual electric motors that are mounted to subframe as to not add unsprung mass but articulate with the wheel somehow. Or more realistically instead of huge angle on undriven wheels, a bit of an angle on all wheels. It’s been done for a while, in the 90s on Japanese sports cars and now German luxo barges.
Something like Ree [1] drives will probably be the future, minimizing unsprung while moving the drivetrain out to the wheels. I could see a top mounted motor driving a splined shaft that is also the kingpin with a sliding pinion driving wheel and you would have full 360 ability just have to keep friction down on the sliding pinion. Basically sliding pillar suspension with the pillar also being the driveshaft.
Or just rotate the whole drive with suspension unit, just needs a much larger wheel well.
The Ree auto thing seems pretty cool. I hope they - or similar - comes to market. Having a car that can four wheel drive and steer with all the traction/anti-spin/abs etc smarts based on a modular component that can be replaced as required sounds great.
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.
I find it is mostly about whether I have the patience to find the perfect position/angle of approach, timing of turn etc. Much easier to simply drive along and find a slightly bigger park.
Combine this with auto-park though. Could be nice.
>being able to transmit the power there (like you need in a FWD application) is the hard part.
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.
I agree this must be a typo! The demo car in the video (BMW i3) is a rear wheel drive car.
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.
Well, FWD cars will always have a potential for tighter turning radius.
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.
Sure, it's true that "FWD cars will always have a potential for tighter turning radius." In practice, that's not the case for conventional front-engine layouts.
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.
I was getting ready to tell you how wrong you are, but you make a good point - if the wheels are turned all the way and the car is RWD, the rear wheels will just put a bunch of pressure on the front wheels without the car turning, if it's not already in motion.
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.
Yeah, from my experience driving bumper cars, they seem to be front wheel drive and have a near 180 degree turning radius. You go in reverse by turning really far.
Not only that, but the headline's gone off the path quite a way. While the I3's front wheels are not driven by an axle, they do rotate on a stub axle, which I guess is technically an axle. It's really just a short metal stick (an accurately manufactured one) that locates the center of the wheel bearings. They're also using the stock steering knuckle, which is the part that actually turns. What they've invented is moving the tie rod connection closer to the stock center of rotation with hacked-up bolt-on bits. That's beer engineer level stuff.
> Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering
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.
BMW has that on many models, rear wheel steering and variable-ratio at the front. It's an option they call Integral Active Steering. The rear is steered either against or with the front, so it will make a tighter turn on a parking lot and it will "crab" on the highway for extra comfort when changing lanes.
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.
This only works for rear wheel drive. The author is terribly confused. To achieve these turns, the torque is applied on the outer rear wheel by braking the inside rear wheel.
If you want to see some even more insane steering angles, check out drift cars. They've been doing this for a while now.
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.
Donut Media (big YouTube channel) has a series of videos that have been uploaded quite recently showing the installation of some of the drift car parts needed to do this super high steering angle gear. They do drifting after the installs and you can see how big an impact it has on maneuverability.
Huh, I always thought they did that because someone (mistakenly) thought it looked cool. The extreme camber actually does help with a measurable aspect of handling?
There are two completely disparate car communities that use camber.
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.
Where does the 225 tire on a 10" wheel come in? I ask because drag racers will run a 275mm on a 14 or 15 inch wheel so there must be a reason the wannabe drift kids do it.
Short sidewalls ostensibly offer better cornering because there is less deflection in the sidewall. They also enable the use of larger brakes. Drag racers don't care about this since they don't turn unless something has gone wrong and they have lots of room to slow down. In drag racing the sidewall is used like a coil spring to capture torque before moving forward and then transmit it to the course.
Stance kids and all their variants do things because it looks good to them.
So in the earlier days of the drift scene, a lot of cars ran small, stretched tires to allow the car to slide easier. Smaller tyre has less grip, and the stretch stiffens the sidewall. When you've got a relatively low powered car this helped a lot.
These days a lot of drift drivers opt for more traditional tire sizing with the aim of getting more grip - as cars get faster and entry speeds into corners also get faster, you want more grip to sustain better angle.
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.
The drag racers use such tire/rim ratio to make a flexible connection to the ground and improve traction.
This https://ssl.c.photoshelter.com/img-get2/I0000uzO7iSXj_JU/fit... is whathappen when your only way to transmit 10k Hp to the ground is 2 pieces of rubber.
most knuckles on drift builds are between 60 and 70 degrees--putting 80 on a RWD electric car is just a great way for the average driver to spin when they try to avoid a collision
One of the things that make this possible is the sudden increase in space in [what was] the engine compartment, now that electric cars are more common.
Most small cars with petrol engines have nowhere near enough space for the wheel to turn like that.
Now you're making me imagine a complicated arrangement with essentially 2 vertical hinges, where the wheel only swings out away from the car regardless which way it's turned. Then it needs no more room in the engine bay. It would rattle and klunk near the center/straight position, but aside from that it's physically possible. It would probably need some kind of belt to drive the axle so that it can bend around a pulley and a changing angle while still delivering the power. Ok I've gone off the deep end...
I think I get what you're saying. The wheels would stick out more on turns. I'm not sure how much of a problem that would be. I could see it potentially being a threat to bicyclists if you're passing one on a corner.
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.
The wheels would scrub like crazy. You just made me realize that essentially the wheels would spread apart on both sides of the car. As the left wheel swings away from the car, so is the right wheel, so either both wheels scrub or if on wheel is agsinst a curb, the other wheel scrubs twice as far.
*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. ;)
With a starting price of $67k (a few grand less than 2023 BMW X6), and a 0-60 that's a couple hundred ms from a 2022 Lamborghini, I think that could be considered well into the higher end of the car world.
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.
Even in the rear of the vehicle where things don't need to steer packaging is a huge priority. Removing the engine won't change this. The tire was never really trying to conflict with the engine anyway. It was the structural bits of the car that kinda need to be there to support the front and the suspension that got in the way.
Exactly. If they had a CV shaft that could support these operating angles at an only slightly insane price point they would be telling us because that's a much bigger accomplishment than a steering linkage that has a lot of angle. Forklifts have a lot of angle and nobody cares. It's a question of straightforward tradeoffs.
I had an 80's era Vanagon with an insane turning angle. Lots of room in the front wheel wells. Could U turn that thing on most residential streets with cars parked on one side.
I wonder how it's propelled? Those don't look like drive wheels in front, and one wouldn't think that engaging the rear wheels would cause it to rotate, since the applied force seems like it would be exactly perpendicular to the front wheels.
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.
Nice find, I never knew that such a thing was done in that way. You really don't want to think about what would happen if that mechanism ever triggered while driving :)
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.
both wheels turn inwards, which means that one of them must have to change direction of rotation. that sounds like a remarkably difficult mechanical problem to solve reliably
I don't think those are drive wheels in front, it looks like they just spin freely.
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 suppose an easy way to do it is to have a little drive wheel sticking out about where the license plate is, and as the front wheels turn inward, one of them makes contact with the drive wheel (like the capstan or pinch roller in a reel-to-reel tape machine). But we don't see anything like that in the video.
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.
The Triumph Spitfire is notable for a few reasons. Besides having a Center of Gravity lower than the axle, giving it zero body roll when cornering, it was also a 12’11” long car with a 12’1” turning radius. It could turn around in less than two car lengths.
I don’t think that’s 80° but it’s damned close. That vehicle ceased production sometime around 1979.
>Center of Gravity lower than the >axle, giving it zero body roll >when cornering
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 have one. It's a RWD car and the front wheels can turn so much that instead of turning, the car will actually start to drag the front wheels unless you're going really slow.
Can confirm. I installed a steering angle limiter to reduce the chance of too much stress on the joints. And yes, the Spitfire can corner until it flies without rolling. Might be me adding a lot to a low cog as well... ;-}
For those who enjoy drifting cars (in some cases at urban sideshows) there are lots of 'angle kits' to tighten a vehicles steering angles, enabling the driver to break the tires loose easier. The reason why mass produced cars don't have these is because it wears the suspension out a lot quicker and puts great stress on the bodyshell.
ChrisFix drift car build -How to Install an Angle Kit (Shopping Cart Angle)
A car is designed to roll forwards on steel banded rubber tires on axle wheel bearings, with suspension designed to absorb bumps and cornering stresses before they reach the body. If you are breaking the tires loose and sliding sideways (still with forward propelling traction) you are putting enormous stresses on components not designed for that which is why racing cars have enormously beefed up suspensions, a roll cage that greatly stiffens the body and polyurethane bushings that give a harsh but very direct 'feel' to the ride.
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.
I rarely use my car's self-parking feature, largely because it forces me to pull forward way too far before it will take over.
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.
As much as I love these concepts, there's a hidden externality to consider: If one car only needs extremely small margins to park, it's possible for conventional cars ahead or behind to lose too much of their normally-expected larger buffer space, and be unable to (easily) leave.
> If one car only needs extremely small margins to park, it's possible for conventional cars ahead or behind to lose too much of their normally-expected larger buffer space, and be unable to (easily) leave.
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.
It was right in front of us all along, all you have to do is mount a moped engine to your one front wheel! On side note, it says that it is an aluminum body, which must have been a pretty fancy thing at the time!
Fascinating to see old ideas make a comeback, like wireless power or that antique Sunbeam toaster.
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.
One thing I am wondering - i mean, everyone in the US knows Ford invented the automobile and the diesel engine was named after an american called Vin, but since when is ZF a US-company?
I am noticing more and more how headlines are promoting the big brand names and ignoring lesser known institutions. If somebody at Stanford or MIT had developed this the headline would be “Stanford/MIT scientists invented….”. With smaller schools they probably would have written “scientists invented”. And with ZF it’s just “mechanics”.
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.
My Dyson vacuum cleaner has a mechanism that can steer in pretty much every angle that isn't gimbal locked. If we're still talking about things you could do without regard to practicality, it could steer in 360 degrees in a RWD.
> 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.
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.
This would be so much more useful on the ever growing pickup trucks in the US. Even a little tighter turning radius would help in parking lots and garages.
I'm mildly amused that the animation for the second car parallel parking seems to be placed too far forward and thus scrapes the bumper of the car in front.
Can the system "tank turn" around an arbitrary point instead of the center of the vehicle? I can imagine some situations where a tank turn might be useful but a common scenario is parallel parking where I would prefer to pivot around the rear bumper.
Think about a circle that has the center in the center of the car, and all wheels on the perimeter. Then each wheel has to turn along the tangent of the circle. That is the circle each wheel will go along when the vehicle is spinning in place. So it's less than 90 degrees. For example the left front wheel turns right, a bit less than 90 degrees.
> Looks cool, but is this a solution in search of a problem?
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.
This sort of thing keeps getting invented over and over for the past hundred years but never seems to stick, and cars stay impossible to parallel park.
Well in the true sense of moving the car completely sideways. They even had it working in the 50s on production cars to some degree with the extra rear wheel.
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"