The "gearbox"

[EVer Hopeful]

I watched the Sandy Munro Model Y teardown videos and was surprised to see the oil filters and hear they were for the "gearbox" that's attached to each motor

I know about diesel electric locomotives and how the 2 stroke dinosaur burner runs at peak efficiency and powers a generator that provides current to traction motors on each axle. So I was surprised to see the Model Y (And I assume the 3, S and X) have a "gearbox"

Why does an electric vehicle need a gearbox? Why not just have direct drive?

Is it a torque thing? Does it actually change gears? or is it more like a speed reducer/increaser like some aircraft have?

 

[GtiMart]

I believe it's essentially to match motor speed to wheel speed to get the right speed range. At max the electric motor spins at say 11000rpm. If you take the wheel circumference (2101mm or 82.7") and multiply that together, you get 23km per minute (~14.3 miles per minute), which is 1380kph (858mph). Assuming that would be possible, it would be hellishly fast. You need to reduce that motor rpm to something that makes sense. It so happens that by reducing, you augment torque as well which makes it possible to use that "small" engine to get good power.

It's not a multi-gear system, one is enough.

 

[EVer Hopeful]

ok makes sense. So basically a reduction gear then - and applying mechanical advantage

Thanks


I just realised that 858mph is actually supersonic!

 

[Brando]

... deep dive to see the details of the 17,500 RPM front motor and drive unit from a 2014-2018 Tesla Model S AWD. See all four motor rotors from the Tesla Model S and Model 3. The video is divided into four sections showing:
1. The motor and gears.
2. The high-performance bearings.
3. The lubrication system.
4. The electrical system.

Check out the modular components and design of the electric motors on the Tesla Models 3 and Y. See how many parts are common and interchangeable.

 

[EVer Hopeful]

thanks - I'll look at those tomorrow