Yes. If you had two motors I imagine they could both drive the same gear. But why even bother locking them together when they could be independent (without a differential)?
It's inside the gearcase with a helical gear bolted to that flange.
Ideally we'd have 2 independant motors up the front as well for off-road torque distribution! :-D
I hear what you are saying about the disadvantages of using brake based traction control, particularly on ICE vehicles, but also on current EV implementations.Ideally we'd have 2 independant motors up the front as well for off-road torque distribution! :-D
I can agree that in many situations traction control on the front will suffice on a TM. But on a dual motor you'd be back down to a 2x4 with two diffs. With a diff and having to brake costs a little bit of power (that the brake absorb until forces reach equilibrium) but more importantly causes lag because the brake is a reactive control method not a pro-active control method.
From what I can tell on Teslas from TFL testing etc, the traction control is a bit more responsive because they seem to have a faster sampling rate wheel rpm sensors and in particular better motor rpm control than an ICE with gearbox etc. But it still has noticable lag, meaning one wheel can and will provide forward force while another won't. That in turn means you won't have maximum forward force to climb and incline etc at low speeds. (But you might with momentum).
In fringe cases having offset forces can also be of benefit, for example when trying to dig yourself out of a sand hole where the sand has the right wet semi dense consistency. You quite literally just inch along like that until you get some form of floatation on virgin ground.
In my over 20 years of experience driving cars (Disco, Land Cruiser, Amorak) with traction control off-road it has been the case that brake modulation is combined with throttle control. This works if you have undulating roads where wheel travel limits grip but the surface has some grip and you don't need to carry momentum.
In sand, which is Australia's premier feature on the beach and many off-road tracks, its floatation that becomes a problem not traction. Traction in sand just digs you a nice hole so that your vehicle bottoms out.
There's two ways to create floatation:
1) have the right tyres that are not low profile, and can be depressurised to create a larger soft and plyable contact patch that conforms to the sand and;
2) enough momentum so that you mostly stay ontop of the sand instead of trying to drive through it.
This is where traction control provides little to no benefit on a open diff. In fact because of the throttle intervention of the traction control it is very difficult to maintain floatation through momentum. To which I typically either turn off traction control and lock the centre diff, (and ESP that also intervenes on the slightest cross track killing the throttle and momentum in the most untimely of ways) or select sand traction control mode that allows some wheel spin and more importantly gives more available throttle.
However, driving down the same stretch of beach with lockers on is even easier, and requires much less throttle in comparison (with the same car) because the forward force is consistent and un-retarded and most importantly with no lag.
In detail lag is bad because there is a response time for the traction control system to respond to wheel slip. This is made up of wheel rpm resolution, signal and cpu time (smaller fraction) and brake caliper response time and modulation, which in turn varies on manufacturer.
Imagine two opposite wheels, if the rotation is not synchronised (which I'm yet to see on a TCS) one wheel is rotating trying to push against another that is not rotating because it has grip. Typically its the wheels that are not turning that have the most grip. Or one rotates and slips even just quarter of a turn before the TCS stops it causing a ledge to form in front of the tyre which it then has to climb on it next turn. This is the downside of TCS in that throttle reduction combined with lagging brake interventions reduces forward force and therefore momentum.
Torque vectoring (like in a Evo) or locking diffs, or quad motor EV, through being able to control drive torque to each wheel makes all of this mute, because the wheels will all spin synchronised at the desired rpm and (except for the diff lockers) will even adjust each wheel according to steering input. So when cornering in sand it essentially forces the car to yaw by wheel rpm not steering angle. (Like a reverse ESP). This gets rid of nearly all the lag resulting in a smooth continuous force that can also create momentum, which in turn makes it easier to overcome track inconsistencies that would otherwise stop you with a TCS intervention.
So from my perspective a SM/DM needs at least one locker/lsd and ideally a TM would also have one in the front for those that take sand seriously. Don't get me started on what the difference is when towing an RV in sand, which is very common here, and that together with the very spread out supercharger availablility (1 in 2,500,000sqkm) a TM is the only option for rural WA.
As for weight distribution having a heavy ICE up front going up a hill is actually better because the front wheels get to do more work. Typically same size EVs will be heavier than a ICE, which doesn't help getting up a sandy track, but in the case of the CT I'm willing to make that sacrifice given I should be able to generate enough momentumwiththe TM.; -) Hopefully its only a 3-400kg more and the longer wheelbase and ground clearance will also help except for rampover angle. Will be fun to test.
I think the 610 on the screen mock ups was a random #.
I don't think we will ever see brakes removed from a road going vehicle - they are the most cost effective way to stop in a hurry. Using motors to stop would require almost as much electricity as it took to accelerate to the same speed.You might get the electronics and software to a insignificant lag time, but brake pressure modulation is a bit harder. Hopefully they can make it much better. Best part is no part, so I'm wondering at what point we might actually see the brakes being removed instead
The Plaid can already accelerate faster than it can decelerate, it's just a question of having quad motor for ABS/ESP and then trying to twist the regulators arm.
What I'd really like to see is them using SLAM computer vision for track and road placement to augment the wheel and accelerometer sensor inputs to for example detect yaw drift and ruts, wheel slippage, track drift, bumps etc. Plus real time suspension adjustments like leaning into corners, predictive bump detection, bounce mode etc like Merc has:
That with 20" travel would be epic offroad because then you could sync the suspension downforce with the traction control.
That's fine for light or moderate braking but to stop quickly, near the limits of tire adhesion, requires stronger magnetic fields than a drive motor can produce organically. The coils would need to be energized and the power would necessarily come from the battery. The ability to brake at the limit of adhesion is required for safety in the event of the unexpected, a deer or elk jumping onto the highway, an errant human, etc, so brakes are not going away for this reason.
just want to meet Crissa someday! we all can meet with our CTs and talk in person!
No.
I already consider the friction brakes on my Model 3 mostly as emergency backup. And, yes, the Cybertruck Tri-motor should have stronger regen but don't expect that much from the single motor, it's likely it will have less effective regen than most current EV's due to it's higher weight and large wheels which will absorb some of the regen of it's singular motor only affecting the rear wheels.
