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Your helpful guide to the Tesla Model 3 parking brake

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I participated in a different thread a long time ago on this same topic. The consensus of that thread (which I didn't search and find to link here) was that the long press of the parking brake button engages the parking brake "tighter" than the normal short press parking brake. It was generally agreed that if you are in Drive and do a long press, the electric actuator that engages the brake is energized for a slightly longer period of time, which since it's a jackscrew mechanism, means it's squeezing tighter. I tend to agree with this consensus in my own experience.

I would also suggest that it's possible that using the long press parking brake application every time/excessively, if it is indeed a tighter hold, could cause premature wear of the rotor or jackscrew or electric actuator, etc. and that may be why Tesla has made two different engagement levels of this brake.

As to the idea that regenerative braking "hold" mode is only using the motors to remain stopped, I do not believe that is the case. The "creep" mode section in the manual says something about the car may roll backwards on an incline even with creep mode enabled. This seems to indicate that they don't use the motors to prevent movement. Also you can feel the brake pedal move when hold mode engages.
 
I participated in a different thread a long time ago on this same topic. The consensus of that thread (which I didn't search and find to link here) was that the long press of the parking brake button engages the parking brake "tighter" than the normal short press parking brake. It was generally agreed that if you are in Drive and do a long press, the electric actuator that engages the brake is energized for a slightly longer period of time, which since it's a jackscrew mechanism, means it's squeezing tighter. I tend to agree with this consensus in my own experience.

I would also suggest that it's possible that using the long press parking brake application every time/excessively, if it is indeed a tighter hold, could cause premature wear of the rotor or jackscrew or electric actuator, etc. and that may be why Tesla has made two different engagement levels of this brake.

As to the idea that regenerative braking "hold" mode is only using the motors to remain stopped, I do not believe that is the case. The "creep" mode section in the manual says something about the car may roll backwards on an incline even with creep mode enabled. This seems to indicate that they don't use the motors to prevent movement. Also you can feel the brake pedal move when hold mode engages.

Hold mode for sure only uses the normal brakes after the motors bring the car to a complete stop. You can hear the master cylinder (Mid 2018 Model 3) engage, the brake pedal depresses a small amount and the brake lights stay on.

My Chevy Bolt uses the motor to come to a complete stop and hold the car without the help of the brake system. This is actually dangerous since once it finishes decelerating the brake lights go out which could lead to being rear ended at a red light or stop and go traffic.
 
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I think the "manual" parking brake is a further level than the "automatic" parking brake when you shift into P.

Lightly place your feet on the brake pedal, don't apply any force at all, just feel it.
Shift into P with a quick push on the stalk button. Nothing happens on the pedal.
Hold the stalk button for the "manual" parking brakes. You hear a quick sound, and the pedal goes down a little.

Difference! What's the difference? I don't know. But it's something. :D


I'm not sure if there is a difference. I tow a 5000 pound boat with our model x, back 10,000 lbs down a steep ramp, use the regular park holds without issue, use the 3-4 second manual park seems to be no difference but maybe the automatic has plenty of holding force that is doesn't matter?
 
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You guys are great detectives, and I really appreciate your efforts to figure this out. However, this discussion should NOT be necessary.

Tesla should explain this in the user's manual -- not just drop a few hints which and be interpreted in different ways. The explanation should begin with a statement as to why we need 2 different ways of setting the parking brake, followed by a description of how (or if) the two methods are different in terms of what they do. Then it Tesla should explain the difference between either of these methods and the Hold mode.

Does anybody have any arm-twisting power over Tesla?
 
This is an old topic flawed with rampant and completely wrong speculation about the parking brake.

The manual is correct. Again.

"Hold" is for driving.
"Park" is for not driving.
"Parking brake" is an extra brake force for when you've parked somewhere steep.
The mechanism is only on the rear axle.
And of course it can be used in an emergency.

Just like every other car ever.
 
This is an old topic flawed with rampant and completely wrong speculation about the parking brake.

The manual is correct. Again.

"Hold" is for driving.
"Park" is for not driving.
"Parking brake" is an extra brake force for when you've parked somewhere steep.
The mechanism is only on the rear axle.
And of course it can be used in an emergency.

Just like every other car ever.
100% correct. "Park" uses a pawl to lock the drivetrain much like what is done in a conventional automatic transmission. "Parking brake" uses the rear brake in addition for a more positive lock and take the stress off of the pawl. I just don't know if it utilizes a drum style brake inside the hat of the rear disc or somehow mechanically squeezes the caliper. I have dealt with both types.

I use the parking brake feature almost everywhere. Especially in my steep driveway. It takes a whole additional second. I can wait.

However, I can't picture any emergency that would call for its use. Isn't that what dual circuit hydraulics are for? Even half braking would be better that throwing out that anchor and locking up the rear wheels.
 
@rpiotro There is no parking pawl and no separate drum brake inside the rear rotor.
@Gasaraki While many PM motors have a strong "cogging" resistance when unpowered Tesla's do not. The motor designer can vary this cogging effect to trade low speed torque for high speed efficiency and quietness among other things.

The rear discs utilize conventional hydraulic single piston calipers but with the addition of a motor driven jackscrew that can push on the back of the piston, allowing them to function as an emergency brake in the event of a hydraulic system failure and ensuring that they will not gradually relax when parked due to fluid leakage.

Jackscrews are pretty crude mechanisms so to reduce wear and noise they only engage with partial pressure in normal park mode. There is no position sensor in the unit - they just run at a moderate voltage and blindly stall the motor for about a second when "park" is engaged, and again at a higher voltage when "parking brake" is engaged.

Model3Rcaliper.jpg
 
Permanent magnet motors are by default in a "locked" or "hold" position. Once you park (P) no energy goes to the back motors and the car is "held" in place. The second parking brake (Hold P) engages the brake to lock the wheels for even better hold.
AC induction, PM, SR, and PMSR do not have appreciable cogging torque. Without a stator field, there is nothing for the magents to react against and they will free spin. An off Tesla can free roll if the parking brake fails. It also rolls if it is in neutral or in drive with hold and creep disabled.

Stepper motors have some power off torque, but it's much less than energized torque. Ultrasomic motors do lock when unpowered.

Any motor feeding a shallow enough worm gear will also lock.
 
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@rpiotro There is no parking pawl and no separate drum brake inside the rear rotor.
@Gasaraki While many PM motors have a strong "cogging" resistance when unpowered Tesla's do not. The motor designer can vary this cogging effect to trade low speed torque for high speed efficiency and quietness among other things.

The rear discs utilize conventional hydraulic single piston calipers but with the addition of a motor driven jackscrew that can push on the back of the piston, allowing them to function as an emergency brake in the event of a hydraulic system failure and ensuring that they will not gradually relax when parked due to fluid leakage.

Jackscrews are pretty crude mechanisms so to reduce wear and noise they only engage with partial pressure in normal park mode. There is no position sensor in the unit - they just run at a moderate voltage and blindly stall the motor for about a second when "park" is engaged, and again at a higher voltage when "parking brake" is engaged.

View attachment 716747
You said, @rpiotro There is no parking pawl and no separate drum brake inside the rear rotor.

Ok, there is no parking pawl. If you say so. That was an educated guess. So how is it locked then? You failed to mention.

Also I did say there may be a mechanism to clamp the the caliper. Did you ignore that on purpose or by oversight?

I hate it when people comment on posts that they did not actually read.
 
Ok, there is no parking pawl. If you say so. That was an educated guess. So how is it locked then? You failed to mention.
Tesla Park gear uses the same electrically driven rear brake actuator as the "parking brake". There are not two systems like on an automatic transmission.

Sandy (munrolive) did a tear down on a different manufacturer's EV that did have a prawl. That setup does provide redudancy and holding force up to the weakest tire's grip. His videos show the guts if you want to see.
 
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I participated in a different thread a long time ago on this same topic. The consensus of that thread (which I didn't search and find to link here) was that the long press of the parking brake button engages the parking brake "tighter" than the normal short press parking brake. It was generally agreed that if you are in Drive and do a long press, the electric actuator that engages the brake is energized for a slightly longer period of time, which since it's a jackscrew mechanism, means it's squeezing tighter. I tend to agree with this consensus in my own experience.

I would also suggest that it's possible that using the long press parking brake application every time/excessively, if it is indeed a tighter hold, could cause premature wear of the rotor or jackscrew or electric actuator, etc. and that may be why Tesla has made two different engagement levels of this brake.

As to the idea that regenerative braking "hold" mode is only using the motors to remain stopped, I do not believe that is the case. The "creep" mode section in the manual says something about the car may roll backwards on an incline even with creep mode enabled. This seems to indicate that they don't use the motors to prevent movement. Also you can feel the brake pedal move when hold mode engages.
I have to state, I tow a 5000 boat, and have stopped on the ramp and used only the basic park brake, it has moved, when I hold the button for the red light I can hear the brakes seemed to apply tighter, and have never had it move in this mode. Maybe it is tightening down more with the hold