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Comment by yladiz | Hacker News Reader

I wonder what happened here. Isn't it a requirement for cars to have emergency brakes for situations when the normal method of braking fails?

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The handbrake is usually fully manual, but it's also not terribly strong especially against an electric motor in its optimal torque region. That leaves you with the regular brakes. Now, I don't know if they're vacuum-assist hydraulic or brake-by-wire on electric cars such as this ..

Every car has some form of brake by wire today. The independent traction control and stability manager relies on electronic intervention between the pedal and the brakes. Even on hydraulic systems they have actuators (a box under the hood) between your master cylinder and caliper.

I drive an almost 20 year old car. I'm going to have such a future shock when I eventually get a new one :(

I got a work trim truck about 5 years ago. No camera, no OnStar, no Bluetooth, no key fob, regular turn key, manual parking brake, etc. It's actually very basic and I love that. It was cheaper than any midsized or large SUV.

I would love it if I could keep it and turn it electric one day. Once the battery densities are 1kwh/kg it would probably swap nicely by replacing the engine/accessories/gas tank with batteries and replacing the transmission with an electric motor. The electronics in most electric cars are a turn off for me. I want it to be simple.

And my grandfather would have complained about the electronics in your work trim truck from 5 years ago. Compared to trucks from the 60's and 70's, that truck was a computer marvel with computers and sensors galore!

Yeah, but the main difference I see is that the new tech being added now had almost nothing to do with driving or improving safety. DFI, ABS, etc great. Infotainment, touchscreen vs buttons, heated seats, autopilot, App to control my car, etc is just garbage I don't need or want, and certainly don't want to pay for.

I don't disagree with you, but I'm what a lot of people would refer to as an old fart! So I'm probably not going to help your case.

It will be interesting though to see what went wrong in this case.

They've been doing this for nearly 30 years now, to varying degrees. It all started with ABS. Then they added traction control, then they added regenerative braking (for EV's) and so on. It's been decades since your brake pedal has had a direct mechanical connection to your drums and your calipers. Even ABS adds computers and sensors between your pedal and the brake.

Generally, these systems are very reliable, but occasionally things go wrong. So far the analysis has been over an order of magnitude of lives have been saved by using this technology than have been lost due to its going awry. Ultimately, this is the argument that's going to be used for self-driving cars.

Even with things like ABS and traction control your pedal does have a direct hydraulic connection. You can still use your brakes if your engine and computer shut off, just without those fancy features (or even vacuum assist).

There's a connection between the brake pedal and calipers for legal reasons, but the ABS system can bypass that by redirecting the fluid.

It's part and parcel of how ABS works.

Handbrakes are frequently being replaced by electronic parking brakes.

Both of my old-fashioned ICE cars have electrically actuated handbrakes. Audi/Volkswagen started implementing them at least 10 years ago.

Regular braking on electric cars partly involves the motors themselves - this regenerative braking helps to convert the kinetic energy of the vehicle back into stored energy in the battery by turning the motors into generators (vs. turning it into as heat as happens with standard friction brakes.) If you ever drive an electric car, you'll find the "engine braking" (i.e. the slowdown you get when you take your foot off the accelerator pedal) is quite a bit more pronounced than on an ICE car.

There are also friction brakes of course, but it's possible the driver, standing on the pedal to try and slow his runaway car, had caused them to overheat, which renders them completely useless.

The slowdown when taking your foot off the pedal is set by the mfg. it is by no means universal even if it’s common to have significant braking. Some cars are tuned to mimic the coasting of ice vehicles.

Yeah. And that's part of why all those cars have fully electronically controlled brakes. They're all balanced so when you put your foot on the brake pedal, the car combines calipers and regenerative braking to induce the deceleration that a driver would expect. From what I've read, it's mostly regenerative unless you're going very slowly or you're braking hard at speed.

If you got a steel wire parking brake you won't even notice pulling it at speed on many models. (Don't try this at home ...). You can usually apply more torque on front wheel drive with the motor than the brake can hold since the front is heavier.

Newer cars usually have some electronic parking brake that might just refuse to do its thing. And the key is not connected to a relay over the batteries usually nowadays.

ABS vents can lock you out from using the main wheel brakes.

Welcome to the future of drive by wire cars.

I hate electronic parking brakes. WTF are they good for in an emergency? I guess that's why they call them parking brakes and not emergency brakes. Are we really that lazy that we can't put on a brake manually anymore?

Because most modern car brakes are complex beats with tons of electronic wizardry. So parking brakes are using those existing electronics. Makes sense.

Not that it would mean much simply being mechanical, I have a car where the parking brake mechanically enganges at the rear prop shaft. And believe, all that brake does is supporting parking if the road isn't too steep.

What electronics would the parking brake need to share? It shouldn't need ABS/stability/traction/etc. It's just an on/off state with wither a mechanical or electronic actuator.

And allmof that actuators include ABS, ESP and whatnot.

The parking brake is a completely separate system (required by law to be separate I'm many cases) that is independent of the hydraulics, ABS, etc. It's literally a cable attached to a lever, or to a motor (the actuator) that applies a shoe in a drum (or in some cases a pad to a rotor).

The parking brake can also just use the rear brake calipers so. And those are attached to ESP and ABS among other things on modern cars. Using the same hardware means interfaces with the systems using said hardware.

If the rear calipers are too hard to move without hydraulics, the parking brake might be a seperate system on the rear axle of a car.

Those seperate systemsnso don't have the power of the main brake system, even just the one on the rear axle.

I don't think I've ever seen a car that uses the hydraulics as a parking brake. Yes, some do utilize the pads in the caliper, but they activate them via a cable, thus bypassing any ABS etc that are all involved hydraulically.

Sure, but said calipers are quote often the same the maonABS brakes use. Hence interdependecies between parking brake and normal brake systems. This dependency cannot be ignored by engineers, and if the choosen trade-off is, for reason ranging from cost over weight to reliability and beyond, an electronic parking brake, well, them that is what it is. And there seems to be something to it, as almost all new passanger cars have those today.

"And there seems to be something to it, as almost all new passanger cars have those today."

That's seems to be a pretty weak argument. You're also forgetting the factor that they can charge extra for more automatic features, or that marketing determined that a significant segment may want it. So it could have little to do with better performance and more to do with positioning and money.

Again, what is they interdependence you speak of? The vast majority of cars have the brake systems completely separate - hydraulic with disc/caliper for regular brakes and a cable with shoes/drum for the parking brake. There's really no reason for interdependence, and you really don't see it in the vast majority of new cars.

Ye I dislike them too. I can never learn whether to push or pull the button without mechanical feedback from tightening a wire.

It is somewhat easier to start in hills if you are bad at matching the torque. I guess that is the marketing benefit. However of the computer messes up the release you are in a bad spot if e.g. half way stuck in a ditch or whatever.

Edit: If you have anti roll back braking the vehicle need to be able to engage the parking brake itself so that the fail state isn't that the car starts to roll again.

Actually, I've had cars with manual parking brakes that had the anti roll back. So the fail state would be that the car starts to roll again. I've never had it fail though. It doesn't seem like that would be a terrible condition as you'd be back to it being a normal car and you weren't in motion anyways.

The vehicle starting to randomly roll backwards is quite bad as it might take a while to notice for the driver. Having a roll back protection that can fail like that is probably worse than none at all. It is quite often pedestrians walk between cars in stand still traffic.

The driver might also leave the car while on hill hold, which might end badly if the parking brake can't be engaged by the computer.

In my experience, features like these need to be very well thought out and seamless, otherwise they confuse and you got no idea what and why stuff happens.

I mean, just having a clutch pedal makes the driver intention way more explicit. I don't think the "press the gas thinking it is the brake flipping the car on a wedge in a garage" accidents happen with manual cars at all, since a panicking driver would depress the accelerator and clutch.

"The vehicle starting to randomly roll backwards is quite bad as it might take a while to notice for the driver."

Sure, drivers might be stupid.

"The driver might also leave the car while on hill hold,"

Sure, some drivers might be extremely stupid. I think it would be hard for the computer to figure out if the action was intended or not. Just look at ll the BS with automatic braking when trying to hook up a trailer to tow. There has to be a cutoff somewhere. If it's really a problem, then we need better driver testing is someone is really that dumb.

"if the parking brake can't be engaged by the computer."

Do any of them actually do this? All the ones I've seen use the regular brakes.

Yes, the hill assist was started to help people in a manual on a hill and I agree that there is more intention when using a third pedal. That's the tradeoff - a system that make the physical act easier while removing intention. Yeah, not having the system might be better in some ways. This shouldn't be that dangerous because we're dealing with stopped vehicles and slow speeds. The tradeoff is stopping many newbies from rolling back into the car behind them, vs hopefully tiny number of people who are so stupid as to exit the vehicle in the 1-2 seconds that the brake is still applied. Better to get rid of that last group with stricter testing.

Ye well I agree in general. It is hard to figure out intention and many cars seem to be on a slippery slope of adding features to protect the user from other features.

Except the surprise rollback. I think it is really hard to notice if you don't expect it, if it starts off slowly.

A Scania truck will engage the parking brake on hill hold if you disengage the seat belt or turn the engine off. The manual variant just allows hill hold for like 5 seconds and then releases the brakes after some warning sounds.

I haven't really tried out how any car with hill hold and electric pbrake behaves when you do strange things, so dunno if any engage the p-brake or locks the transmission.

Interesting. That truck is the first one I've heard of that can do that.

Tesla automatically engages the parking break if the driver exits the vehicle while stopped.

On my hybrid Fusion, if I push the button for the parking break while it is moving then it pulses the parking break. Which I suppose is good for a controlled slowing the vehicle down. If it is barely moving then it locks the parking break on and stops instantly, but anything over a few miles an hour gets the pulsing (and slowing) action.

Interesting. Are you sure it actually uses the parking brake though? Do you like hear the "screw motor" (if it is one of those).

Yes, there is a distinctive sound from the parking break motor that I hear engaging. I only hit the switch one time while moving at moderate speed, as it didn't quite sound that healthy, but noticed that it noticeably started slowing the car while I heard the thump-thump-thump of the parking break going on and off (almost like the sound of anti lock breaks kicking on, but not as powerful of a stop and sound / drag was coming from the back wheels only). Here is their page on it: https://www.fordservicecontent.com/Ford_Content/vdirsnet/Own...

Also, if I put it in gear and step on the gas, the parking brake automatically releases (you hear the whir of the motor releasing the brake). Something else -- if it is running in drive and stopped, and you open the door and take your foot off the brake and get out of the car, it automatically shifts into park too. Triggered by engine running, while foot on brake, if you take the seat belt off and open the door and take foot off brake it returns to park.

They've never been strong enough to stop your car in an emergency if the engine is running away.

Anyway, the reason they've gone electronic is to add hill assist. Let your foot off the brake and you stay in place until you hit the gas. A lot of people like that.

The hill assist is done through hydraulic actuators of the regular brakes.

Emergency brakes won't bring you to an immediate stop, but they do slow you rapidly if properly adjusted. If your engine is running away, shifting to neutral or killing it is more important.

> Isn't it a requirement for cars to have emergency brakes for situations when the normal method of braking fails?

No. Cars usually have parking brakes, which can be more or less useful as emergency brakes, but that is not their primary function and they are not designed or usually very useful for that purpose for a vehicle stuck with more than minimal power being applied.

This article (https://www.thescottishsun.co.uk/motors/11320530/electric-ve...), which features a picture of the driver looking displeased, doesn't mention the emergency break but says that he tried everything, even turning off the engine. Police had engineers from the car company on the phone trying to come up with ways to stop the car. I have to assume the emergency brake came up as an option.

Maybe activating the emergency brake requires using a touch screen?

The emergency brake is probably electronic and it wouldn't shock me if it was locked out if the car was in motion or defeated by some other similarly idiotic assumption. I hope I'm able to be buried in my 20+ year old cars at this point.

I think the MG4 has a brake by wire system, although those are supposed to have a failsafe built in but if it's not electro-hydraulic there might not be a mechanical link between the pedal and the callipers. Handbrake will be electric too, so activation depends on enough of the car brain functioning.

Keyless ignition usually has an override for a running car too, in a ford pushing the button three times within a few seconds turns the combustion engine off. Wonder if that's the same in electric cars, otherwise the only way I can think to kill it is isolate the batteries, same as emergency services would do in an accident.

Another, more detailed account link to elsewhere in the comments pointed out that the police were even on the phone with engineers from the car manufacturer - if there was such a magic sequence apparently it didn't work. Yeah! Software Everywhere!

There's the parking break, but depending on how fast you're going it might be a bad idea to use that instead of crashing in a straight line (you probably gonna swivel)

the "emergency" brake is actually the parking brake. it cannot hold up against engine power. if you have a car you can try this yourself.

apparently the car in question was stuck in a mode where there was a constant torque request (throttle setting) that was enough to overpower the brake. or, the car helpfully wouldn't allow engaging of the parking brake while the car was still in "D" mode.

i would also have tried opening the door. many cars will take the car out of gear when a door is opened. (frustratingly to me, as it can in rare occasion be helpful to crack open the door when in reverse, to look down for parking lines etc. a very loud warning chime would be better for me personally than this nanny feature.)

60 Minutes had a program where they looked at cars that did not stop when you press the break. And all of their tests, no matter what, even if they were holding down the gas pedal, pressing the break, brings the car to a stop.

Unless there is shown to be a physical defect or fault that prevented the brakes engaging, I am inclined to believe the driver is at fault.

Was this the good old "Toyota unintended acceleration" fiasco? I still don't know who to believe on that one.

"Unless there is shown to be a physical defect or fault that prevented the brakes engaging, I am inclined to believe the driver is at fault."

What about an electronic defect?

That's the interesting part to me - you're relying on the data logs from a system for court which in theory might not match what actually happened and may not leave an observable physical defect. For example but not specific to this case, if there was an error that actuated a brake through the traction control system but it wasn't recorded due to the initiating error.

I'm sympathetic to car manufacturers in situations of very brief unintended acceleration, where the driver could plausibly have hit the accelerator instead of the brake, or something loose in the car could have got stuck under one of the pedals.

But in this case, the problem lasted long enough for the driver to call the police, and a convoy of police vehicles to escort him for some 15 minutes.

To me it sounds like the driver's reaction was calm and controlled, with plenty of time to assess the situation. Another report on the same incident [1] says the driver tried the park button, the engine off button, police got advice from engineers, they even tried passing the car key to another car. And that the dash showed "nine warning lights."

Given these facts, it seems very unlikely the driver was, for example, confusing the accelerator and the brake, or failing to press the brake sufficiently hard.

[1] https://www.thescottishsun.co.uk/motors/11320530/electric-ve...

Time to make a phone call doesn't necessarily mean anything. This poor family[0] had time to call 911 and still crashed.

https://www.twincities.com/2010/02/23/a-lexus-barreling-out-...

It wasn't just time to make the phone call - it was time to make the call, police respond, get the manufacturer on the phone too, and then 15 minutes in to the response taking the final action.

The article says that the driver was met by a convoy of police cars and then after a 15 minute drive around with the police escort, they did a rolling stop.

I could imagine someone making a mistake and accidentally pressing the wrong pedal, etc., but it seems very unlikely that after 15 minutes at 15mph in a police convoy, the guy still couldn’t work out how to press the brake pedal properly.

https://www.thescottishsun.co.uk/motors/11320530/electric-ve...

> Police worked with their engineers and tried everything to bring the EV motor to a stop.

Your thoughts?

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