Lightning and 4WD

[SmoothJ]

So I had my Lightning for well over a year now, and I love it. However someone today asked me more of a mechanical question related to the 4WD system that I didn't know, and I then become a bit curious.

I know the axles are directly connected to the motor, and I see that in the diagram below. However like any system with 4WD, if its always on you would need to be cautious if one wheel is going a bit faster than the other. How does the F150L accommodate those types of situations if both are directly connected to the motor?

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[WildBlue]

There is a differential inside the motor/inverter package. It's all an integrated unit. So the motor rotor is connected to the differential through a reduction gear (or two) and the differential to the drive axles.

 

[TaxmanHog]

The rear motor unit has differential and a locker for those rare occasion when you want full power to both rear wheels in slippery & off-road conditions.

The front motor does not have a locker.

 

[Zaptor]

IIRC the Lightning is technically an AWD not a 4WD...

 

[swajames]

Ford describes the Lightning drivetrain as 4WD and not AWD on their technical specifications. I don't know that's a distinction that makes a difference for many users, but it's here on the spec sheet.

https://media.ford.com/content/dam/...-lightning/pdf/F-150_Lightning_Tech_Specs.pdf

 

[TaxmanHog]

Ford describes the Lightning drivetrain as 4WD and not AWD on their technical specifications. I don't know that's a distinction that makes a difference for many users, but it's here on the spec sheet.

https://media.ford.com/content/dam/fordmedia/North America/US/product/2022/f-150-lightning/pdf/F-150_Lightning_Tech_Specs.pdf

I was always under the impression that AWD is all the time with no ability to disengage the front drive as found on 4WD with manual or automatic hub locks.

 

[wautard1]

Hamsters…the hamsters run on their wheels at different speeds.

 

[Zaptor]

Hamsters…the hamsters run on their wheels at different speeds.

TIL HP = Hamster Power

 

[Toby57]

Ford describes the Lightning drivetrain as 4WD and not AWD on their technical specifications. I don't know that's a distinction that makes a difference for many users, but it's here on the spec sheet.

https://media.ford.com/content/dam/fordmedia/North America/US/product/2022/f-150-lightning/pdf/F-150_Lightning_Tech_Specs.pdf

Of course ford is going to call it 4wd. Ford knows that Joe redneck is not gonna buy an all wheel drive pickup. It has got to have the 4X4 on the side.

 

[carys98]

I was discussing this at the Drive Electric event yesterday. I’m not sure what the real criteria is for 4WD vs AWD but I always considered having a transfer case with variable gearing to be one factor needed for 4WD. Since the only real purpose of 4 low is to allow you to increase low speed torque it really isn’t a factor in an EV. I would consider the Lightning 4WD based on what it can do but some purists might disagree.

 

[Adventureboy]

So, a couple of things that I use to differentiate between 4WD and AWD. In my view, traditional 4WD locks the axles together with the transfer case to turn at the same rate. This is why when you try to turn into a parking spot with 4WD active, it binds things up since the axles want to turn at different rates but aren't able (ie. in a sharp turn, the front axle needs to turn faster than the back axle to accommodate the larger turn radius of that axle.). Traditional ICE F150s work this way as do most other brand 4WD.

AWD has a looser coupling between the axles. Most ICE AWD vehicles employ a part-time electronically controlled "clutch" to lock the axles together when traction is needed. They are usually either front or rear-wheel drive by default with clutch-activation to engage the secondary axle when needed. There are many variations on this but suffice it to say, the axles are not locked together manually unless the vehicle decides to do it. True 4X4 enthusiasts in the back country climbing mountains do not want traditional AWD since they cannot control if all axles are getting the power they need and most (if not all) do not have locking differential making them weak at best for true 4wheeling since if they are teetering on a front and rear wheel, both axles will spin the wheel with no weight and will produce no drive (ie. you are stuck, even though 2 of the 4 wheels are solidly on the ground)

Most 4X4s do not have a locking front differential unless it is installed aftermarket so they are really 3X4s which in most cases is quite sufficient to go back country. With a locking differential, you always have at least 2 wheels providing power - either both rear (with differential locked and one front wheel in the air) or one front and one rear (with both front wheels on the ground and one rear in the air). The worst case scenario is if you have a rear wheel in the air and a front wheel in the air (teetering) - then you only have 1 wheel driving forward - but you still have 1 wheel driving - AWD would be stuck in this scenario.

EVs open a new era with independently powered axles. This is FAR better than the traditional AWD that needs an elecro-mechanical mechanism to engage both axles. By default, our Lightnings drive both axles at the rates they need to be turned. They can turn at independent rates as needed for the situation and has a locking rear differential to cover 99% of back country situations.

Our Lightning is a hybrid since it provides all the traction of a traditional 4X4 (unless an aftermarket front differential lock is installed) without the turning limitations caused by axle locking. This is the best of both worlds and IMHO is better than traditional 4WD and traditional AWD. Let's call it IAWD (Independent All Wheel Drive). I'll take it over either traditional 4WD or AWD.

[Update]: You should not lock the rear differential while on-road, especially in slippery conditions like snowy and icy roads. In slippery conditions, it can be far worse than an unlocked differential since torque can cause the rear axle to lose traction on both wheels causing potential skids. The locking differential is intended for slow-speed off-road applications only where "Teetering" can happen. In rare cases of heavy snow, it can be beneficial but only at slow speeds. Please use it carefully.

BTW, EVs can achieve true 4-wheel drive with 4 independent wheel-based motors (which some EVs have). Let's see what the T3 comes up with ;-)

 

[RickKeen]

Note that modern traction control and stability control systems using a combination of braking and modulating the power applied can dramatically reduce wheel spin. If one of the front wheels is off the ground, the other one is still going to have non-zero torque because the traction control is not going to just let the free wheel spin.

 

[chillaban]

Note that modern traction control and stability control systems using a combination of braking and modulating the power applied can dramatically reduce wheel spin. If one of the front wheels is off the ground, the other one is still going to have non-zero torque because the traction control is not going to just let the free wheel spin.

Yep though this is useful for brief situations like when half your truck is on a soft shoulder or if you’re trying to climb over a curb. A dedicated locking / limited slip differential is still good for prolonged off road conditions as brakes do overheat.

 

[RickKeen]

Yep though this is useful for brief situations like when half your truck is on a soft shoulder or if you’re trying to climb over a curb. A dedicated locking / limited slip differential is still good for prolonged off road conditions as brakes do overheat.

I was thinking about the front axle on the F150 Lightning. The back already has locking capability.

I used my Lighting the other day to haul my boat. The conventional 4WD truck ahead of me spun some wheels a bit on the wet pavement of the boat ramp. My Lighting in off-road mode (locked rear) walked right up with no wheel spin (pulling a larger boat).

 

[HOTAS]

This was a good thread from a couple years ago. It made me appreciate how good electric drive can be at so many things, and specifically providing 4WD, and advanced AWD.
Lightning‘s system is really neither in the traditional sense, yet both in the modern sense.
Traditional 4WD, being strictly mechanical, is a pretty basic mechanical connection of one driven axle to another. Binding in turns is its compromise, so it’s selectable, and used part time.
Traditional AWD is a full time system.
It introduces a “slip” mechanism. Whether it be a front/rear or side to side, this slip mechanism can come in many forms.
Most of these slip mechanisms result In a wear component that needs addition maintence, cooling and eventual replacement. Think limited slip differentials and Torsen differentials and brake calipers via traction control braking.
The advantage is full time engagement, and torque sensing characteristics. But heat and wear is the disadvantage.

With electric drives, we can get the best of all worlds, 4WD, AWD, Limited slip, E-locking, power transfer bias , and even torque vectoring !
Lighting has 5 out of 6 of those features.
And it’s all done with essentially no maintence nor wear.

(With 3 or 4 motors (at the hubs) there can be torque vectoring).

So my point is, the Lightning is such a remarkable truck, but very under appreciated and certainly misunderstood. Why they’re not selling like hot-cakes is unfortunate !

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