Comment on Tesla confirms it has given up on its Cybertruck range extender to achieve promised range

• UnderpantsWeevil@lemmy.world ⁨1⁩ ⁨month⁩ ago

  Two in the back, one in the front.

  The Shocker

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  • Tja@programming.dev ⁨1⁩ ⁨month⁩ ago

    That’s the other way around.

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• acockworkorange@mander.xyz ⁨1⁩ ⁨month⁩ ago

  That makes even less sense. Distributing mechanical power on non steering wheels is easy, but for steering wheels requires a more complex and expensive coupling, as well as power losses. Just… why?

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  • _stranger_@lemmy.world ⁨1⁩ ⁨month⁩ ago

    I believe the three motor versions is to add extra power under load to the rear wheels.

    The motors are essentially in line with the wheels (they have gearing but it’s minimal and internal to the motor housing, not attached like an automatic transmission would be, if that makes sense.)

    The “three motor” design is just the single motor design up front and the dual motor design in the back.

    I’m not sure if they ever actually released the single motor version though.

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    • ChickenLadyLovesLife@lemmy.world ⁨1⁩ ⁨month⁩ ago

      extra power under load to the rear wheels

      Lol like there’s enough room back there to add a load.

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      • acockworkorange@mander.xyz ⁨1⁩ ⁨month⁩ ago

        It’s supposed to tow. In theory.

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      • Usernameblankface@lemmy.world ⁨1⁩ ⁨month⁩ ago

        The load of getting this brick up to speed quickly so the driver can show off

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      • acockworkorange@mander.xyz ⁨1⁩ ⁨month⁩ ago

        Basically they use the same size motor everywhere, and your total torque and power is dependent on how many you’ve got?

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    • Excrubulent@slrpnk.net ⁨1⁩ ⁨month⁩ ago

      More power to the rear makes sense because you get more traction at the rear under normal acceleration, not just when carrying a load. It’s pretty typical of electric cars to do this, just like it’s typical to have bigger brakes on the front of all cars, because there’s more traction at the front under braking.

      There’s also the issue of torque vectoring. Without a differential, torque vectoring is essential, but under acceleration torque vectoring to the rear wheels is much more effective than to the front wheels, so that’s another reason to split the rear power but not the front.

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  • FreedomAdvocate@lemmy.net.au ⁨1⁩ ⁨month⁩ ago

    Why? More power……

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  • XeroxCool@lemmy.world ⁨1⁩ ⁨month⁩ ago

    How do you figure dual front motors would alleviate any of what you said a front diff would need? Dual front motors will still be rigidly mounted to the chassis, requiring flexible couplings. The rear is also independent, requiring the same flexible couplings whether it’s a diff or motors. CV axles all around.

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    • acockworkorange@mander.xyz ⁨1⁩ ⁨month⁩ ago

      You wouldn’t need a front differential, for one. But you’re right, unless they somehow made a directly wheel coupled motor that turned with the wheel, it l still needs CV couplings.

      As for rear, they don’t need CV axles. Two simple cross couplings are enough. The speed variability happens significantly when the wheels turn, going up and down is a negligible issue. Cars have been using the much chapter and simple cross couplings in the rear for decades.

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      • _stranger_@lemmy.world ⁨1⁩ ⁨month⁩ ago

        The CT has four-wheel steering, so yeah, it’s actually more complicated than a regular truck in that regard. I remember reading something about the mechanisms to make that possible taking up a shitload of room.

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      • XeroxCool@lemmy.world ⁨1⁩ ⁨month⁩ ago

        Look under any RWD IRS passenger vehicle and you’ll find nearly every single example uses CV axles, not u-joints. U-joints have famously irregular speed variation as the angles change in steady rotation, so the constant velocity joint is far more common for the half axles

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