Generally speaking almost all mechanical steering systems are not dynamic though, you are missing the point entirely. It can't change the spacing of the teeth on the fly - steer by wire effectively does. The number of turns lock to lock on a mechanical system is almost always the same, regardless of speed.
With steer by wire, you can easily implement say one turn lock to lock at low speed for easier parking, increasing to 2-3 turns at highway speeds for stability. Which is essentially exactly what the recent Lexus model with such a system does. At low speed it can turn its wheels from one extreme to the other in just 150 degrees of steering wheel rotation - no hand over hand turning etc. 150 degrees is essentially unthinkable on a mechanical rack and pinion system, as it would make the car incredibly twitchy on a highway.
It can't change the spacing of the teeth on the fly.
Geez, Elon really ought to start a goalpost moving company. But hey I'll play: yes, yes it can. That's precisely what BMW's active steering is, yes it's mechanical, yes it varies the ratio depending on speed, and yes it's been around for a couple decades now.
BMW active steer doesn't get remotely close to 150 degrees lock to lock when maneuvering (minimum rotation reached is ~720 degrees/2 turns), or offer the infinite and instant range of adjustability you can get with a drive by wire system. But sure, it's just the same. I couldn't care less whether the system is on a Tesla or not, its just abundantly clear there are some design and packaging advantages when you lose the mechanical link in anything with a steering wheel.
The vast, vast majority of rack and pinion systems ever made, both old and modern, don't adjust number of turns lock to lock at all, whereas the ability to essentially infinitely adjust it is inherent in all drive by wire steering systems.
Before we change the goalposts again it's worth noting that Tesla (and to a lesser extent Lexus) make vehicles where the primary focus is on the gadgets and BMW's focus is on the driver interface.
BMW active steer doesn't get remotely close to 150 degrees lock to
lock when maneuvering
Well, no. Super fast steering ratios are not an advantage, they're a necessary evil with a square steering control. There's nothing inherent in the BMW design that would prevent such a fast ratio beyond the reputation for emulating analog interfaces with quite a bit of fidelity. It speaks more to the intended use (gadget vs car) than to the underlying technology itself.
its just abundantly clear there are some design and packaging
advantages when you lose the mechanical link in anything with
a steering wheel.
Every time I see this I wonder if the commentor has seen a hydraulic power steering pump. They're tiny as hydraulic and pneumatic drives are often quite a bit smaller than comparable electric ones (e.g. cordless vs pneumatic power tools). The only clear advantage that electric steering offers is one of efficiency (as a result of not driving a hydraulic pump all of the time). The rest is largely a series of trade offs, especially if you look at recirculating ball / worm gear vs rack and pinion drives.
> Every time I see this I wonder if the commentor has seen a hydraulic power steering pump. They're tiny as hydraulic and pneumatic drives are often quite a bit smaller than comparable electric ones (e.g. cordless vs pneumatic power tools).
The pump or motor size is totally irrelevant to this discussion and to the packaging advantages.
There is no steering column with steer by wire. If you have seen a mechanical steering column, as found in all hydraulic and electric power steering systems, it requires a significant amount of space to route from cabin to the front wheels, and you are limited in the paths and angles it can take to reach the rack. This is completely gone in steer by wire - that's the packaging advantage - not the pump, not the motors.
Taken to the extreme, you can do designs that are completely impossible with mechanical steering columns - see the Canoo design for example, which uses steer by wire to create a cabin that would literally be impossible with a steering column:
You could even design interiors that can switch from left hand to right hand drive, with a sliding steering wheel. It also reduces the cost of shipping left and right hand drive variants, as you no longer need to engineer space on both the left and right sides of the car to fit the column for different markets.
But no need to take only my word for it; ZF, as in your earlier examples, also make the exact same arguments about packaging (and also about infinite adjustability, fwiw):
> "SbW's (Steer by Wire) additional advantages include gaining space in general and new design options in the cockpit... There is now more legroom because there is no longer a steering structure running through it."
> "In terms of steering experiences – from sporty-direct to comfortable-relaxed – every setting is possible in the same car. The system can also translate the same steering wheel movement variably depending on the driving situation, i.e. for parking and at low city speeds, the wheels angle (very) strongly for the change of direction, while they angle only slightly at high highway speeds."
> "we can make the steering ratio completely variable depending on the driving situation – unlike the fixed steering ratios used for a mechanical connection between the steering wheel and the front wheels"
> "Installing steer-by-wire steering systems reduces the assembly effort needed to build today's right-and left-hand drive versions of the same passenger car model."
I have in fact had to remove the column on one of my cars, mostly to deal with the attached electronics. It's a relatively small device with a couple of u-joints.
see the Canoo design for example, which uses steer by wire to create a
cabin that would literally be impossible with a steering column
See the first three generations of Volkswagen vans.
There is literally air between the steering wheel and the rest of the car in the Canoo, as well as significantly more front leg room - its nothing like the VW, which has an almighty big steering column between the drivers legs. Unless of course ZF and the rest of the car industry are also wrong about it taking less room to package and permitting new designs?
If you have seen a column - congratulations, you will then know it needs room to route to the wheels, and is restricted in the paths it can take to get there quite significantly, vs of course plain ole wires that can snake any way you like. Those restrictions are exactly why your VW vans have a column between the drivers legs.
This is getting genuinely funny now, however I think I'm about done with this one. Enjoy the rest of your day.
> "SbW's (Steer by Wire) additional advantages include gaining space in general and new design options in the cockpit... There is now more legroom because there is no longer a steering structure running through it."
As far as I know there is no technological problem for BMW system to have whatever desired rate of adjustability and speed of reaction. It uses planetary gearset with adjuster motor connected to one of the gears - a bot similar to how Toyota Prius's transmission works. So it's more a question of how manufacturer decided it should feel for the user.
With steer by wire, you can easily implement say one turn lock to lock at low speed for easier parking, increasing to 2-3 turns at highway speeds for stability. Which is essentially exactly what the recent Lexus model with such a system does. At low speed it can turn its wheels from one extreme to the other in just 150 degrees of steering wheel rotation - no hand over hand turning etc. 150 degrees is essentially unthinkable on a mechanical rack and pinion system, as it would make the car incredibly twitchy on a highway.
> https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-b...