5 ms·

Do we have a problem because of this? I use the handbrake when driving standard transmission in Europe but never when driving an automatic. Never had an issue b

Do we have a problem because of this? I use the handbrake when driving standard transmission in Europe but never when driving an automatic. Never had an issue because of it or heard of anyone who has. Obviously my experience is limited but genuinely curious - what problems have we suffered because people w automatic transmissions just use "park"? If "none" then I guess I can't lament the disappearance of the handbrake although I did find it odd that my highlander only has the button which engages itself.

yencabulator 3y ago
To move a car in "P" without brakes, you just need to cause enough force to make the parking pawl fail. And it's just a little cog on a gear, it can be worn down by continuous use, without you knowing. I would not trust that on a hill, no way. > Constant use of only the parking pawl, especially when parking on a steep incline, means that driveline components, and transmission internals, are kept constantly under stress, and can cause wear and eventual failure of the parking pawl or transmission linkage. https://en.wikipedia.org/wiki/Parking_pawl#:~:text=Constant%20use%20of%20only%20the,parking%20pawl%20or%20transmission%20linkage https://en.wikipedia.org/wiki/Parking_pawl#:~:text=Constant%....
blamazon 3y ago
Automotive engineers view it as a problem but most drivers probably are unaffected by it in their lifetime. A passenger car's automatic transmission is generally just a bad choice of a device to immobilize a car's wheels. It is difficult to service and has other uses (namely: propel the vehicle) that are prioritized in the design. By contrast, wheel brakes are designed to be easily serviced and their design is centered around stopping the car. When relying on the transmission for park, this engineering trade off results in the entire lateral force of the car resting on a tiny little piece of metal inside the transmission, that isn't designed to be constantly worn, the only thing keeping the car in place, easily replaced, etc. There's also this aspect of - transmissions are mutable, they can go in a lot of different vehicles. You can have the same transmission in a 2000lb sports car and a 8000lb truck. How big should the parking pawl in that transmission be? How do you make that decision before you even know what vehicles the transmission will go into? What happens when your transmission that was originally designed for a 2000lb sports car ends up 20 years later in a 9,000lb truck towing a 3,500lb trailer? The parking pawl does not change. Brakes will be serviced dozens of times over the lifetime of a vehicle, while the transmission might never be serviced. That's enough reason alone to leave the important task of immobilizing the car to the brakes, not the transmission, in my opinion.
- xyzelement 3y ago
  As an engineer I can appreciate what you are saying. But as a product manager: the question I am asking is if it matters? Do we have problems (eg transmissions failing faster) because of this. Or people getting injured etc? Because if not, it's just a distinction without a difference? EDIT: I think you added the first sentence of your post after I read and replied to it. That was the answer I am looking for, thank you.
  - deleted 3y ago
    [deleted]
marcosdumay 3y ago
Also, if the problem is safety related, is it really solved? Because I don't think the parking break of any car is able to stop the car when the engine is pushing it. Instead, I've seen some catch fire because the driver tried that. If it's just for maintenance, I don't see any problem with it being electric.
vintagedave 3y ago
This surprises me. In Australia, the way I was taught to park an auto was: * Apply the brake (the pedal) * Place the transmission into park * While the brake pedal is still pressed, apply the handbrake * Release the brake pedal. This means the car is held in place by the handbrake with the transmission park as a backup, rather than the transmission park being the only thing holding the car. Bonus: if you park on a slope, turn the wheels towards the pavement so that if the car starts moving, it will hit the pavement edge instead of running straight down the road.

yencabulator 3y ago

To move a car in "P" without brakes, you just need to cause enough force to make the parking pawl fail. And it's just a little cog on a gear, it can be worn down by continuous use, without you knowing. I would not trust that on a hill, no way. > Constant use of only the parking pawl, especially when parking on a steep incline, means that driveline components, and transmission internals, are kept constantly under stress, and can cause wear and eventual failure of the parking pawl or transmission linkage. https://en.wikipedia.org/wiki/Parking_pawl#:~:text=Constant%20use%20of%20only%20the,parking%20pawl%20or%20transmission%20linkage https://en.wikipedia.org/wiki/Parking_pawl#:~:text=Constant%....

blamazon 3y ago

Automotive engineers view it as a problem but most drivers probably are unaffected by it in their lifetime. A passenger car's automatic transmission is generally just a bad choice of a device to immobilize a car's wheels. It is difficult to service and has other uses (namely: propel the vehicle) that are prioritized in the design. By contrast, wheel brakes are designed to be easily serviced and their design is centered around stopping the car. When relying on the transmission for park, this engineering trade off results in the entire lateral force of the car resting on a tiny little piece of metal inside the transmission, that isn't designed to be constantly worn, the only thing keeping the car in place, easily replaced, etc. There's also this aspect of - transmissions are mutable, they can go in a lot of different vehicles. You can have the same transmission in a 2000lb sports car and a 8000lb truck. How big should the parking pawl in that transmission be? How do you make that decision before you even know what vehicles the transmission will go into? What happens when your transmission that was originally designed for a 2000lb sports car ends up 20 years later in a 9,000lb truck towing a 3,500lb trailer? The parking pawl does not change. Brakes will be serviced dozens of times over the lifetime of a vehicle, while the transmission might never be serviced. That's enough reason alone to leave the important task of immobilizing the car to the brakes, not the transmission, in my opinion.

xyzelement 3y ago
As an engineer I can appreciate what you are saying. But as a product manager: the question I am asking is if it matters? Do we have problems (eg transmissions failing faster) because of this. Or people getting injured etc? Because if not, it's just a distinction without a difference? EDIT: I think you added the first sentence of your post after I read and replied to it. That was the answer I am looking for, thank you.
- deleted 3y ago
  [deleted]

marcosdumay 3y ago

Also, if the problem is safety related, is it really solved? Because I don't think the parking break of any car is able to stop the car when the engine is pushing it. Instead, I've seen some catch fire because the driver tried that. If it's just for maintenance, I don't see any problem with it being electric.

vintagedave 3y ago

This surprises me. In Australia, the way I was taught to park an auto was: * Apply the brake (the pedal) * Place the transmission into park * While the brake pedal is still pressed, apply the handbrake * Release the brake pedal. This means the car is held in place by the handbrake with the transmission park as a backup, rather than the transmission park being the only thing holding the car. Bonus: if you park on a slope, turn the wheels towards the pavement so that if the car starts moving, it will hit the pavement edge instead of running straight down the road.