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Operational brakes vs 'brakes actually capable of overcoming the motor' are two entirely different things. You'll find that for many vehicles, the brakes alone

Operational brakes vs 'brakes actually capable of overcoming the motor' are two entirely different things. You'll find that for many vehicles, the brakes alone will not be sufficient to stop if the motor is attempting to accelerate; you need to shift to neutral (potentially destructive), or kill the engine. Plenty of people accidentally drive around with their emergency brake engaged and don't realize it.

throwaway0a5e 4y ago
Pretty much every vehicle except maybe some heavy trucks with really, really, really deep first gears has brakes that can over-power everything else. This should be obvious when you think about what % of brake force it takes to break traction vs what percent of engine power it takes.
bin_bash 4y ago
> the brakes alone will not be sufficient to stop if the motor is attempting to accelerate Malcolm Gladwell went into detail about how this is BS on Revisionist History: https://www.youtube.com/watch?v=1N3naJ0P0gM https://www.youtube.com/watch?v=1N3naJ0P0gM It doesn't pass the smell test either: what car accelerates faster than it can stop?
- tesseract 4y ago
  > It doesn't pass the smell test either: what car accelerates faster than it can stop? A dragster? But more seriously, modern high-performance electric cars (such as some Tesla models) are capable of both acceleration and braking pretty much at their tires' adhesion limit. I would still expect the mechanical braking system to be designed to be able to overcome the maximum torque of the motor although I do not know whether or not that is in fact the case.
mywittyname 4y ago
> You'll find that for many vehicles, the brakes alone will not be sufficient to stop if the motor is attempting to accelerate; Maybe in 60s cars with 4 wheel drums. But the brake force on even basic modern cars is sufficient to overcome like 800hp. Go ahead and give it a shot in your own car and see. I have a 400+hp car with shitty brakes and it will still stop completely and readily if I hold down the throttle and brakes at the same time in second gear. Now, if you ride the brakes, they will overheat and lose stopping power. So you're going to want to actually try to stop the car.
- throwaway0a5e 4y ago
  >Maybe in 60s cars with 4 wheel drums. 60s 4wd truck or SUV will probably fit the bill. Nice deep 1st gear, ~2:1 low range, and available with manual brakes on the lower trim levels. In the lowest gear it can probably just idle over the force of a small women or scrawny teen pushing the pedal.
sp332 4y ago
Working brakes are mechanically able to stop an out of control engine. The limit is how much force a person can apply to the brake pedal. NHTSA and manufacturers target a 5th percentile person being able to stop the car, assuming power braking is still working. PDF https://www.autosafety.org/wp-content/uploads/2015/03/The-Brakes-Will-Not-Always-Overcome-the-Engine.pdf https://www.autosafety.org/wp-content/uploads/2015/03/The-Br...
matheusmoreira 4y ago
> you need to shift to neutral (potentially destructive) Why is it destructive?
kurthr 4y ago
Please specify a vehicle. It would be very rare for a standard passenger vehicle (non-bob tail semi). Even for muscle cars your emergency stopping distance from 60mph is almost always shorter than your 0-60 distance. This is one of the proof points for people who experience "sudden acceleration" while pushing hard on the "breaks" since the breaks could stop those cars. There are drive by wire elements/booster of many modern cars and EVs do have higher low speed torque. Perhaps if you were going fast and got the breaks nice and hot before they could stop the car? It's interesting to me that the guy admitted he was intentionally exceeding the speed limit. For the Model S Plaid, however, it may well be the case: https://www.youtube.com/watch?v=rh12lK53hss https://www.youtube.com/watch?v=rh12lK53hss

throwaway0a5e 4y ago

Pretty much every vehicle except maybe some heavy trucks with really, really, really deep first gears has brakes that can over-power everything else. This should be obvious when you think about what % of brake force it takes to break traction vs what percent of engine power it takes.

bin_bash 4y ago

> the brakes alone will not be sufficient to stop if the motor is attempting to accelerate Malcolm Gladwell went into detail about how this is BS on Revisionist History: https://www.youtube.com/watch?v=1N3naJ0P0gM https://www.youtube.com/watch?v=1N3naJ0P0gM It doesn't pass the smell test either: what car accelerates faster than it can stop?

tesseract 4y ago
> It doesn't pass the smell test either: what car accelerates faster than it can stop? A dragster? But more seriously, modern high-performance electric cars (such as some Tesla models) are capable of both acceleration and braking pretty much at their tires' adhesion limit. I would still expect the mechanical braking system to be designed to be able to overcome the maximum torque of the motor although I do not know whether or not that is in fact the case.

mywittyname 4y ago

> You'll find that for many vehicles, the brakes alone will not be sufficient to stop if the motor is attempting to accelerate; Maybe in 60s cars with 4 wheel drums. But the brake force on even basic modern cars is sufficient to overcome like 800hp. Go ahead and give it a shot in your own car and see. I have a 400+hp car with shitty brakes and it will still stop completely and readily if I hold down the throttle and brakes at the same time in second gear. Now, if you ride the brakes, they will overheat and lose stopping power. So you're going to want to actually try to stop the car.

throwaway0a5e 4y ago
>Maybe in 60s cars with 4 wheel drums. 60s 4wd truck or SUV will probably fit the bill. Nice deep 1st gear, ~2:1 low range, and available with manual brakes on the lower trim levels. In the lowest gear it can probably just idle over the force of a small women or scrawny teen pushing the pedal.

sp332 4y ago

Working brakes are mechanically able to stop an out of control engine. The limit is how much force a person can apply to the brake pedal. NHTSA and manufacturers target a 5th percentile person being able to stop the car, assuming power braking is still working. PDF https://www.autosafety.org/wp-content/uploads/2015/03/The-Brakes-Will-Not-Always-Overcome-the-Engine.pdf https://www.autosafety.org/wp-content/uploads/2015/03/The-Br...

matheusmoreira 4y ago

> you need to shift to neutral (potentially destructive) Why is it destructive?

kurthr 4y ago

Please specify a vehicle. It would be very rare for a standard passenger vehicle (non-bob tail semi). Even for muscle cars your emergency stopping distance from 60mph is almost always shorter than your 0-60 distance. This is one of the proof points for people who experience "sudden acceleration" while pushing hard on the "breaks" since the breaks could stop those cars. There are drive by wire elements/booster of many modern cars and EVs do have higher low speed torque. Perhaps if you were going fast and got the breaks nice and hot before they could stop the car? It's interesting to me that the guy admitted he was intentionally exceeding the speed limit. For the Model S Plaid, however, it may well be the case: https://www.youtube.com/watch?v=rh12lK53hss https://www.youtube.com/watch?v=rh12lK53hss