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Comment by giantg2 | Hacker News Reader

Electronic parking brakes are so stupid. They offer no real value and eliminate the ability to safely use a secondary brake in an emergency.

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Automatic disengage when accelerating and automatic engage when parking means means one less thing to think about. Just get in the car, put in gear and go.

EVs also have very powerful motor braking that can get the car to a stop if the hydraulic brakes are busted.

This. I don't think about parking brakes. Get into parking spot, open doors - car engages parking brake itself. It's nuts all cars don't do this yet.

On my peugeot 5008, pressing the electronic parkong brake button for more than cca 500ms while driving fully engages all brakes of the car (not only rear ones), but ABS remains functional. So in an emergency, one could theoretically still use this as an emergency brake. Although I agree that it's quite dumb, because it of course wouldn't work in case of computer/electric failure. What a shame indeed.

That sounds quite useless to me. I've never been in an emergency where I could afford a 500ms delay before engaging the brakes, and also had ample opportunity and presence of mind to keep my finger uninterrupted on a dashboard button.

It also wouldn't work if you lost hydraulics.

Thats the same case with all brakes in use more or less. Also modern brakes have two hydraulic systems, in the case that one of the loops (front or rear) breaks there should be sufficient pressure to apply the brakes still.

Sometimes its front/rear and sometimes it is diagonal, but it should still do the emergency trick.

Regular parking/emergency brakes use a cable instead of hydraulics.

They also don't really stop a moving car, its a parking brake.

Just wanted to add, a EPB used for emergency stop in his scenario is just using the regular stopping brakes, its not an emergency brake either.

"They also don't really stop a moving car, it's a parking brake."

This is false. Have you ever tried it? I can say from experience they will stop a moving car.

It will if maintained properly. If you don't use it often it becomes loose and won't hold.

In my part of Europe it's the main issue for technical inspections, as most people drive automatic and we don't have hills, so we just put it in P when we park. The handbrake rarely gets used.

I have, they're tiny shoes and it'll lock up your rear wheels at best.

I would suggest that anybody reading NOT try this unless you have a quite large and empty lot with no public access. Pay close attention, they are not called Emergency Brakes, they are called Parking Brakes.

The stated purpose of these brakes are to ensure your car wont roll away while parked. Anybody with a manual transmission knows the ritual of shifting into 1 or Reverse and turning their wheels toward the curb while parked even while the parking brake is engaged.

They won't serve you in an emergency. Here's Mitch Hedberg on "Emergency brake": https://www.youtube.com/watch?v=kMKV1B0vuI8

They are smaller shoes. You could lock them up, but you could also modulate it (success depends on the type and user experience). Instead of a joke, here's some actual information.

https://www.nationwide.com/lc/resources/auto-insurance/artic...

What cars is this the case in? All the cars I've ever driven have hydraulic-assisted brakes but can still be used without the assist in a pinch, if you really use your leg muscles. It seems REALLY dangerous to have no ability to manually actuate your brakes. If an ICE car like this with an electronic parking brake were to stall while going downhill, you'd be completely screwed.

At least computers are redundant and far likely less to fail.

Hydraulic brakes also have a bit of redundency built in so you can still hopefully stop in the event of a mechanical failure like a line bursting.

The value is not having to put mechanical linkage all the way to the back.

I'd think if it would be cheaper to leave it manual they would.

But I'm appalled at more and more choices that make cars more error-prone in emergency.

I'd never want brake by wire car. Even if the mechanical reliability would be the same, one coding error and brakes are gone

They're not worried about a $20+installation cable that they can copy-paste from the last car.

An EV "needs" the electric actuator to replicate the park position in a conventional automatic transmission. The motor has no mechanical brake so the parking brake is automatically applied via software. Once you can do that why run the cable?

There's som minor addition value in sharing the system with ICE models that don't need it and programming them to cycle the system from time to time so that they don't rust up and stop working like cables are inclined to in automatic equipped cars.

"Once you can do that why run the cable?"

In case of electronic/hydraulic failure when driving. If you want to replace the park position of a transmission, then they should do that with something that actually mimics that. You could use a sprocket and pawl on the motor output shaft.

Some EVs, not all. My Lightning has a parking pawl.

An EV "needs" the electric actuator to replicate the park position in a conventional automatic transmission.

Noteworthy fact: most early automatic transmissions had no park position. Like a manual, you put them in neutral and set the parking brake instead.

I find it hard to believe that running an electric cable to motor/actuator and programming the computer to use it via a button is cheaper than running a cable attached to a lever.

Cables do stretch and rust

And motors/actuators wear out and can rust too. A cable is still much cheaper.

> I'd never want brake by wire car.

I'm willing to bet in just 5 years fully break-by-wire systems (aka no hydraulics) will be 2x more reliable.

I had not thought much about it until now, but when I did, I guessed it was a cost-cutting move, as it seems to piggyback on equipment needed for other features (principally ABS).

Now that you've mentioned it, I'm wondering if the auto manufacturers needed to get a bunch of regulators to drop secondary/emergency braking requirements in order to do this?

My guess is they implemented whoever they felt like and the regulations only require a "parking" brake, but don't talk about implementation.

Not to mention the cool handbrake turn when you're a teenager.

As I once heard: when the lever pops, the panties drop.

Not my classiest comment, but I figured someone would get a chuckle from it.

What other mechanism would you use to park an EV then??

The same sort of mechanism that transmissions use today - a sprocket and pawl or similar somewhere between the motor and wheels.

So now you're building a transmission just to park? Seems like you're not sure how that actually works.

Adding a sprocket to a rotating shaft is not the same as adding a transmission.

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