6 ms·

At this rate I would not be half surprised to see in-wheel type hubmotors as used in some electric skateboards [1] or the OneWheel [2]. That kind of changes t

At this rate I would not be half surprised to see in-wheel type hubmotors as used in some electric skateboards [1] or the OneWheel [2]. That kind of changes the whole drive train concept. [1] https://www.backfireboards.com/products/backfire-g3-with-super-flexible-deck https://www.backfireboards.com/products/backfire-g3-with-sup... [2] https://news.ycombinator.com/item?id=29797315 https://news.ycombinator.com/item?id=29797315

YEwSdObPQT 5y ago
Electric Wheel motors have been used before. The LeTourneau had an electric wheel back in the 1950s. This was IIRC mainly used for Earth moving equipment though. They probably don't make sense on cars though as explained by other people here.
- bch 5y ago
  Or Porsche[0]. In 1898. [0] https://arstechnica.com/cars/2020/02/check-out-the-first-ever-electric-car-designed-by-porsche-the-1898-p1/ https://arstechnica.com/cars/2020/02/check-out-the-first-eve...
  - mkl 5y ago
    That was electric, but didn't use a hub motor: "Foregoing Porsche's new wheel-hub motor, the P1 employed a rear-mounted drive unit."
    - bch 5y ago
      So it does. I was recalling Porsche lore from memory and thought I had a correct reference. Iirc Porsche built an electric 4-motor (hub) car for the Paris Expo about this time… Oh, here we go: > In 1900, at the Paris Exposition Universelle…[0] [0] https://www.automobiliardent.com/index.php/home/article_detail/272 https://www.automobiliardent.com/index.php/home/article_deta...
pengaru 5y ago
Aptera uses in-wheel motors in their EV reverse trike thingy.
oppositelock 5y ago
It's unlikely. Anything attached to the wheels is "unsprung mass", and it has a huge effect on the handling and comfort of a car. Furthermore, for efficiency, you really want to minimize rotational inertia in the wheels. Sure, for slow vehicles where these things don't matter, hub motors work great, but not for your typical road going car. They could put one of these near each wheel and drive the wheels via axles.
- justsomehnguy 5y ago
  > They could put one of these near each wheel and drive the wheels via axles. Pro: get rid of the differential. Cons: have less power overall, less efficiency (for an electric motor?), more losses. Probably.
  - jaclaz 5y ago
    I don't think there are any losses on a (reasonably short, i.e. without intermediate supports) axle transmission, the only form of attrition are bearings and on both sides of such a setup you need one anyway, unless the same bearing is common between the wheel hub and the motor (i.e. the motor is actually the hub).
- stingraycharles 5y ago
  Could you elaborate a bit more? Do I understand correctly that in today’s world of energy efficiency, the car’s mass distribution has to be carefully tuned for maximum efficiency, and hub motors throw that off balance? Intuitively, I always figured that having mass on an object that’s very low to the ground is a good thing, but I can imagine it’s something different when it’s attached to a wheel.
  - giva 5y ago
    Apart from the mass distribution, if you look at a car travelling on an uneven road from the reference point of the car itself, you will see the wheels moving up and down very quickly to keep contact with the ground. My understanding is that adding mass to the wheels will slow them down and thus increase the time they don't touch the ground, reducing the grip.
robocat 5y ago
I would love to see a 4WD with inhub motors, to get extreme clearance.

YEwSdObPQT 5y ago

Electric Wheel motors have been used before. The LeTourneau had an electric wheel back in the 1950s. This was IIRC mainly used for Earth moving equipment though. They probably don't make sense on cars though as explained by other people here.

bch 5y ago
Or Porsche[0]. In 1898. [0] https://arstechnica.com/cars/2020/02/check-out-the-first-ever-electric-car-designed-by-porsche-the-1898-p1/ https://arstechnica.com/cars/2020/02/check-out-the-first-eve...
- mkl 5y ago
  That was electric, but didn't use a hub motor: "Foregoing Porsche's new wheel-hub motor, the P1 employed a rear-mounted drive unit."
  - bch 5y ago
    So it does. I was recalling Porsche lore from memory and thought I had a correct reference. Iirc Porsche built an electric 4-motor (hub) car for the Paris Expo about this time… Oh, here we go: > In 1900, at the Paris Exposition Universelle…[0] [0] https://www.automobiliardent.com/index.php/home/article_detail/272 https://www.automobiliardent.com/index.php/home/article_deta...

pengaru 5y ago

Aptera uses in-wheel motors in their EV reverse trike thingy.

oppositelock 5y ago

It's unlikely. Anything attached to the wheels is "unsprung mass", and it has a huge effect on the handling and comfort of a car. Furthermore, for efficiency, you really want to minimize rotational inertia in the wheels. Sure, for slow vehicles where these things don't matter, hub motors work great, but not for your typical road going car. They could put one of these near each wheel and drive the wheels via axles.

justsomehnguy 5y ago
> They could put one of these near each wheel and drive the wheels via axles. Pro: get rid of the differential. Cons: have less power overall, less efficiency (for an electric motor?), more losses. Probably.
- jaclaz 5y ago
  I don't think there are any losses on a (reasonably short, i.e. without intermediate supports) axle transmission, the only form of attrition are bearings and on both sides of such a setup you need one anyway, unless the same bearing is common between the wheel hub and the motor (i.e. the motor is actually the hub).
stingraycharles 5y ago
Could you elaborate a bit more? Do I understand correctly that in today’s world of energy efficiency, the car’s mass distribution has to be carefully tuned for maximum efficiency, and hub motors throw that off balance? Intuitively, I always figured that having mass on an object that’s very low to the ground is a good thing, but I can imagine it’s something different when it’s attached to a wheel.
- giva 5y ago
  Apart from the mass distribution, if you look at a car travelling on an uneven road from the reference point of the car itself, you will see the wheels moving up and down very quickly to keep contact with the ground. My understanding is that adding mass to the wheels will slow them down and thus increase the time they don't touch the ground, reducing the grip.

robocat 5y ago

I would love to see a 4WD with inhub motors, to get extreme clearance.