Cybertruck has no Parking Pawl in its Tranmission. Lightning does.

[RickKeen]

Reading some more about the Cybertruck from a tech familiar with Teslas.
It sounds like it has two parking brake mechanisms. The first is activated when the truck is put into park. It uses the regular electric-hydraulic power brake actuator to hold the brakes on using the hydraulic brake calipers, pads, and rotors. Same as the driver just holding the brake pedal down or a hill hold mode.

On top of that, same as the Lightning, the CT has an Electric Parking Brake that can be manually activated that uses a separate electric motor on each rear caliper to push on the brake caliper cylinder and pad as shown in the video in post #36, above.
https://www.f150lightningforum.com/...-tranmission-lightning-does.22950/post-445730

It was not clear which can put more pressure on the caliper.
An EPB is considered more reliable for long term parking since the screw mechanism, once cranked to full pressure by the motor, will continue to hold regardless of any hydraulic leak down or dead battery. No power is required to hold it on. (you will have a problem trying to disengage it with a dead battery)

Still have found no mention of a mechanical parking pawl in the motors/transmission.

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[Runaway Tractor]

Really? Isn't that what the OP and this whole tread is about? I'm not the OP.

You're not a lot of things in this thread and it will only get worse the more you reply apparently.

 

[TaxmanHog]

Ten plus threads have been closed/deleted over the past twelve month for disrespectful and offensive posts in this section of the forum.

Please exercise a measure of courtesy, keep the cussing down, keep the politics to yourself, do not denigrate any public personalities, and most importantly treat fellow members decently, these are basic conditions of participation in the forum.

Reports about this thread are being reviewed....................

 

[ctuan13]

Reading some more about the Cybertruck from a tech familiar with Teslas.
It sounds like it has two parking brake mechanisms. The first is activated when the truck is put into park. It uses the regular electric-hydraulic power brake actuator to hold the brakes on using the hydraulic brake calipers, pads, and rotors. Same as the driver just holding the brake pedal down or a hill hold mode.

On top of that, same as the Lightning, the CT has an Electric Parking Brake that can be manually activated that uses a separate electric motor on each rear caliper to push on the brake caliper cylinder and pad as shown in the video in post #36, above.
https://www.f150lightningforum.com/...-tranmission-lightning-does.22950/post-445730

It was not clear which can put more pressure on the caliper.
An EPB is considered more reliable for long term parking since the screw mechanism, once cranked to full pressure by the motor, will continue to hold regardless of any hydraulic leak down or dead battery. No power is required to hold it on. (you will have a problem trying to disengage it with a dead battery)

Still have found no mention of a mechanical parking pawl in the motors/transmission.

Yeah thats better than a single system, but at its core, both systems still interface with the same mechanism, the friction brakes. That is a single point of failure that frankly flies directly in the face of the concept of redundancy, which is critical on any vehicle system, but especially one responsible for keeping the vehicle stationary when parked.

I see lots of people defending Tesla's decision to forgo the parking pawl, but to me, it's inexcusable. On a lighter, smaller vehicle that is likely to never see a trailer or any significant payload, it might be acceptable. But on a "truck" that is supposed to be able to tow 11000 pounds and carry signicant payload, this is frankly an inexcusable measure in cost-cutting in my opinion.

Tesla went on and on about how thorough they were in designing and implementing multiple redundancies and failsafes in their steer-by-wire system and yet for their park-securing system, they effectively only have one interface system to stop the vehicle from rolling.

I'll add that friction brake systems can be easily compromised by rotor contamination from water, ice, grease and oil. All of these contaminants have the potential to drastically reduce the friction coefficient of the rotor/pad interface to below the rolling force of the vehicle or its attached load.

All in all, if you feel it's safe, then more power to you. And in most circumstances, I'm sure it is. But then again that's not what redundancy is implemented for, it's for saving your bacon when all the everything goes wrong. To me, a super heavy EV without a physical parking pawl system in addition to a e-brake or parking brake, is poor design.

 

[Firn]

This thread is about the Lightning having a parking pawl and the CT possibly not having one. So, what is it you guys think about this subject then if the CT does in fact have no mechanical parking mechanism?

You misunderstand.

A thread discussing that if, or if not, having a mechanical driveline lock is what is happening. But you keep making statements that the answer is already a forgone conclusion and anyone who doesn't share your view has to prove how it us unsafe.

The point is that YOU are not DISCUSSING it. Your sole counterpoint has been to invent things claiming that is what others are saying, that is the issue.

Can it be a discussion? Yes. But people are frustrated because that is not what you are doing.

Yeah thats better than a single system, but at its core, both systems still interface with the same mechanism, the friction brakes. That is a single point of failure that frankly flies directly in the face of the concept of redundancy, which is critical on any vehicle system, but especially one responsible for keeping the vehicle stationary when parked.

I see lots of people defending Tesla's decision to forgo the parking pawl, but to me, it's inexcusable. On a lighter, smaller vehicle that is likely to never see a trailer or any significant payload, it might be acceptable. But on a "truck" that is supposed to be able to tow 11000 pounds and carry signicant payload, this is frankly an inexcusable measure in cost-cutting in my opinion.

Tesla went on and on about how thorough they were in designing and implementing multiple redundancies and failsafes in their steer-by-wire system and yet for their park-securing system, they effectively only have one interface system to stop the vehicle from rolling.

I'll add that friction brake systems can be easily compromised by rotor contamination from water, ice, grease and oil. All of these contaminants have the potential to drastically reduce the friction coefficient of the rotor/pad interface to below the rolling force of the vehicle or its attached load.

All in all, if you feel it's safe, then more power to you. And in most circumstances, I'm sure it is. But then again that's not what redundancy is implemented for, it's for saving your bacon when all the everything goes wrong. To me, a super heavy EV without a physical parking pawl system in addition to a e-brake or parking brake, is poor design.

But why?

For decades the physical parking brakes are considered FAR superior to the built in pawl. The pawl was a simple weak system for convenience, not strength. ANYTIME you were parking any load or on any angled surface it was recomended to use the parking brake because the parking pawl was considered woefully insufficient. Why would that be reversed here?

 

[RickKeen]

For old-school 4wd trucks, the traditional auto transmission parking pawl's effectiveness depends on what traction mode the transfer case and axles/hubs were left in. If you were in fully-locked 4WD mode, then all the wheels would be locked.

In the lightning, the pawl locks the rear motor output. Not sure if it also actuates the rear diff lock. So at best it locks the two rear wheels. If the diff is not also locked, then you end up with "one wheel braking". If that one wheel loses traction, then the pawl is doing nothing to stop the other 3.

The ECB's on the two rear wheels lock both rear wheels but don't do anything for the front.

Not sure if the Lightning also engages the hydraulic brakes when parked like was described for the CT, and if it does, those could be on all 4 wheels.

 

[StevenC56]

Apparently I totally misunderstood the point of this thread discussion. Sorry for frustrating some of you.

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