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Comment by smaili | Hacker News Reader

Details surrounding the issue in question:

In a statement the firm said the electric parking brakes installed on Model S and Model X "may contain a small gear that could have been manufactured improperly by our third-party supplier".

If the gear were to break, the parking brake would continue to keep the car from moving, but the parking brake would be stuck in place, it added.

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So this is a matter of brakes being unable to be _disengaged_ from standing rather than engaged at speed?

Yup, and specifically the _parking_ brake not the normal brakes used when driving.

But now all the people using their parking brake while moving will be performing a possibly unsafe action!

The thing I haven't figured out yet is whether this is the brake engaged when you shift an automatic transmission into park, or if it is the emergency brake. If the latter, I'm not sure what the big deal is, since you should almost never use the e-brake.

It's the parking brake, not the transmission in park.

Though commonly called an e-brake, the parking brake is actually intended to be used when parking, especially when parking on a hill.

https://en.m.wikipedia.org/wiki/Parking_brake

Ah, I see. I was always taught not to use the parking brake. If not used regularly, it has a tendency to seize up, particularly in cold conditions. On all but the steepest slopes, park in an automatic is sufficient. With a manual transmission, I'd either put it in gear in 1st or reverse, depending on the orientation.

IIRC Teslas only have a simple single gear transmission, so I suspect the parking brake is mechanically more similar to the e-brake on a car with an automatic transmission.

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