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Huh, that explains something I saw when at the Fremont event -- somebody started heading away from the boarding area when *screech* *clunk* they just full stopped and seemed a bit confused re: why.
I didn't expect the parking brake would do that, but the behavior seems consistent to what you described.
gg_got_a_tesla
Model S: VIN 65513, Model 3: VIN 1913
The Green car at 4:40 pm or so on Saturday?! That explains that quick stop tire skid marks and all.
So if you accidentally tap the P when going freeway speed you'll come to a screeching halt (maybe hurting the car)? That can't be right...
gg_got_a_tesla
Model S: VIN 65513, Model 3: VIN 1913
Wouldn't that happen if you pull the handbrake handle in your current car?!
I suppose you might be saying that it's easier to accidentally push the P button than pull the handle in other cars?!
First, you'd have to crank a hand brake tremendously hard. I've never owned car where I could lock up the rear tires with the hand brake without brutal force applied. And I've never accidentally applied a hand brake.
And yes to your 2nd question, accidentally tapping P looking to twiddle the lights on/off, or wipers, or cruise control or some such. or just brushing against it for some reason. God knows I've tripped the blinker or wipers more than a few times in my life by accident, I mean it's rare, but it definitely happens.
Tommy
Member
No, it can't be right. In addition to the parking brake being applied when the car is placed in park the parking pawl is also engaged to stop the wheels rotating. Therefore, there must also be a fail safe override(s) that prevent such a scenario from occurring.
strider
Active Member
On the Roadster (and I assume model S) there is a pin (pawl) that activates to actually lock the differential from turning when placed in Park. So the transmission will "lock". The parking brakes are a separate system.
Usually there is a speed at which it will just beep and go into neutral or some similar behavior. In the Prius this is over 6 mph. If you hit P at 5 mph the parking pawl will engage and you'll get a lurch. No harm can be done because there is a break-away clutch to protect the drivetrain. I'd be really surprised if the Tesla acts differently.
I was told the Model S didn't have a parking pawl at all -- just the second set of rear calipers, electrically actuated by putting the car into Park.
I would be very interested to hear how the car handles an attempt to put it into Park while it is moving with any significant forward speed. They could do something like the Prius does, for example, with the power button. If you press and hold a Prius power button for several seconds at freeway speeds, the car shifts to neutral. It's basically a way to prevent a runaway. Doesn't help if the brakes fail, but the Prius does at least have a physical parking brake pedal.
I would be very interested to hear how the car handles an attempt to put it into Park while it is moving with any significant forward speed. They could do something like the Prius does, for example, with the power button. If you press and hold a Prius power button for several seconds at freeway speeds, the car shifts to neutral. It's basically a way to prevent a runaway. Doesn't help if the brakes fail, but the Prius does at least have a physical parking brake pedal.
Makes sense because there is no transmission to put a parking pawl in.
Doing that powers off (a hard power down) the Prius as well as shifting to neutral. Putting the Prius in Reverse or pressing P puts it into neutral without powering down the car and without a waiting period.
The Roadster has it. Let's call it a mechanical lock to stop transfer of mechanical energy in the drive train, and we can agree on it?
In wet climates, hand brakes applied to the brake rotor tend to stick to it within a day or two as the rotor develops rust.
So, I'd like to have such a mechanical lock system in the drive train in addition to the parking brake caliper. Or, Tesla should use a non-rusting rotor material.
Please, not another "Never rains in California" issue like the Roadster's PEM fans.
gg_got_a_tesla
Model S: VIN 65513, Model 3: VIN 1913
Felt like a noob and had to lookup "parking pawl". Given the recommendation in that Wikipedia article and given the (easy) way to engage P in the Model S (the button to be pushed in on the steering stalk rather than with a full gear shift lever), am happy that the Model S is not using a parking pawl.
There's a gearbox. The Roadster has a parking pawl. The car has some "drive lash" when it's engaged, so when on a hill I let it roll to the stop before applying the parking brake. Otherwise it lurches when I release the parking brake, which sometimes annoys my passenger.
When parked in my garage, I leave the Roadster's parking brake off. Otherwise if the brakes are wet the resulting corrosion somehow sticks the pads to the rotors. It breaks free with a big clunk when I pull out of the garage. Sounds like that isn't possible for the Model S, so I hope they've improved the pad/rotor materials.
Tommy
Member
I am going to wait to hear it from Tesla that there is not a mechanical lockup of the gears. While it may not be called a "parking pawl", IMHO I can't imagine relying on a parking brake alone to hold a hill in, say, San Francisco's notorious steep streets. That is just waiting for a disaster to happen; my sense is there is another backup to the parking brakes.
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