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I am not familiar with EV internals, but do modern EVs have an electric drive train:ie, are there drive shafts and differentials and clutches in the modern EV o

I am not familiar with EV internals, but do modern EVs have an electric drive train:ie, are there drive shafts and differentials and clutches in the modern EV or is it just independent motors coupled to the wheels? What about breaking? Is done on the wheel or on the motor?

bjelkeman-again 8y ago
Breaking is generally done with both using the electric motor as a generator and with breaks. A lot of driving in a Tesla for example means you hardly use the breaks at all. The drivetrain is relatively simple. One motor on the rear or front axel, sometimes one on each. https://www.teslarati.com/tesla-model-3-drivetrain-design-elon-musk-master-plan/ https://www.teslarati.com/tesla-model-3-drivetrain-design-el...
jhayward 8y ago
> are there drive shafts and differentials and clutches in the modern EV or is it just independent motors coupled to the wheels? All of the above, although by far the most common power train arrangement is motor per axle with a 2-speed transmission for however many axles are driven. Regenerative braking is done at the motor and augmented by conventional brakes. Very few designs use motor-per-wheel.
- permatech 8y ago
  What electric cars uses clutches? Which use 2-speed transmissions? Tesla doesn’t seem to use either.
  - jhayward 8y ago
    The Tesla sportster had a two-speed transmission, and I'm fairly certain the model S also used one as well. I know they replaced a ton of them on the early production. Later production doesn't seem to find the transmission necessary.
corbet 8y ago
No drive shafts, no clutches. I always thought it should be a motor for each wheel, but nobody seems to be doing that now. Both physical brakes and regenerative braking exist. (One real surprise with our new Bolt is that you can't do regenerative braking when the battery is full - there's no place to dump the energy. Makes sense once you think about it). The simplicity of electric cars is one of their big advantages, but also one of the reasons that US dealers (other than Tesla, obviously) aren't enthusiastic about selling them. There's almost no periodic maintenance to be done, and little to break, so little in the way of post-sale revenue.
- zaarn 8y ago
  There are some companies working on "1 motor 1 wheel", it's still very early on though...
  - arethuza 8y ago
    Doesn't that cause problems with relatively high unsprung mass - which causes its own problems?
    - tomatotomato37 8y ago
      Usually the motors are still mounted to the chassis with some type of halfshaft interface in those cars rather than being directly mounted to try wheels; there's just more of them
  - analognoise 8y ago
    The first "1 motor 1 wheel" design I can think of is from 1904: https://en.m.wikipedia.org/wiki/Lohner-Porsche https://en.m.wikipedia.org/wiki/Lohner-Porsche So it isn't THAT early, if you add in 115 years of development.
loolatrix 8y ago
braking: both, recuperation is done on engine side, but there are still brakes at the wheels. Recuperation doesn't cover all necessary brake performance, plus, you don't want to have a car without brakes at the wheels. The moment the driveshaft breaks, you wouldn't be able to brake your car, if braking was only facilitated by the engine. This actually killed at least one race driver, Jochen Rindt, Monza 1970, in his Lotus 72.
prolepunk 8y ago
Another question about braking. When the car brakes about 70% of breaking force is at the front wheels, so wouldn't regenerative breaking be more effective for the cars with the motor at the front and not at the back (like in Tesla)?
- sbradford26 8y ago
  While true that breaking with the front tires would be more effective. In a BEV the weight distribution is closer to 50:50 so rear breaking is more effective than in a normal ICE car with the engine in the front. This gives regenerative braking more than enough grip for normal braking but probably not emergency braking which would require more braking power. So what it comes down to is that if the rear tires are not breaking loose and the car isn't using friction brakes then the car is recovering as much energy as it can with regenerative breaking.

bjelkeman-again 8y ago

Breaking is generally done with both using the electric motor as a generator and with breaks. A lot of driving in a Tesla for example means you hardly use the breaks at all. The drivetrain is relatively simple. One motor on the rear or front axel, sometimes one on each. https://www.teslarati.com/tesla-model-3-drivetrain-design-elon-musk-master-plan/ https://www.teslarati.com/tesla-model-3-drivetrain-design-el...

jhayward 8y ago

> are there drive shafts and differentials and clutches in the modern EV or is it just independent motors coupled to the wheels? All of the above, although by far the most common power train arrangement is motor per axle with a 2-speed transmission for however many axles are driven. Regenerative braking is done at the motor and augmented by conventional brakes. Very few designs use motor-per-wheel.

permatech 8y ago
What electric cars uses clutches? Which use 2-speed transmissions? Tesla doesn’t seem to use either.
- jhayward 8y ago
  The Tesla sportster had a two-speed transmission, and I'm fairly certain the model S also used one as well. I know they replaced a ton of them on the early production. Later production doesn't seem to find the transmission necessary.

corbet 8y ago

No drive shafts, no clutches. I always thought it should be a motor for each wheel, but nobody seems to be doing that now. Both physical brakes and regenerative braking exist. (One real surprise with our new Bolt is that you can't do regenerative braking when the battery is full - there's no place to dump the energy. Makes sense once you think about it). The simplicity of electric cars is one of their big advantages, but also one of the reasons that US dealers (other than Tesla, obviously) aren't enthusiastic about selling them. There's almost no periodic maintenance to be done, and little to break, so little in the way of post-sale revenue.

zaarn 8y ago
There are some companies working on "1 motor 1 wheel", it's still very early on though...
- arethuza 8y ago
  Doesn't that cause problems with relatively high unsprung mass - which causes its own problems?
  - tomatotomato37 8y ago
    Usually the motors are still mounted to the chassis with some type of halfshaft interface in those cars rather than being directly mounted to try wheels; there's just more of them
- analognoise 8y ago
  The first "1 motor 1 wheel" design I can think of is from 1904: https://en.m.wikipedia.org/wiki/Lohner-Porsche https://en.m.wikipedia.org/wiki/Lohner-Porsche So it isn't THAT early, if you add in 115 years of development.

loolatrix 8y ago

braking: both, recuperation is done on engine side, but there are still brakes at the wheels. Recuperation doesn't cover all necessary brake performance, plus, you don't want to have a car without brakes at the wheels. The moment the driveshaft breaks, you wouldn't be able to brake your car, if braking was only facilitated by the engine. This actually killed at least one race driver, Jochen Rindt, Monza 1970, in his Lotus 72.

prolepunk 8y ago

Another question about braking. When the car brakes about 70% of breaking force is at the front wheels, so wouldn't regenerative breaking be more effective for the cars with the motor at the front and not at the back (like in Tesla)?

sbradford26 8y ago
While true that breaking with the front tires would be more effective. In a BEV the weight distribution is closer to 50:50 so rear breaking is more effective than in a normal ICE car with the engine in the front. This gives regenerative braking more than enough grip for normal braking but probably not emergency braking which would require more braking power. So what it comes down to is that if the rear tires are not breaking loose and the car isn't using friction brakes then the car is recovering as much energy as it can with regenerative breaking.