Over the past few decades, electrification has resulted in the virtual elimination of several once-key automotive liquids. Power steering fluid is the most obvious example across the board, but electric vehicles have also dispatched with engine oil, automatic transmission fluid, and of course, gasoline. However, innovators in the industry aren’t done yet. Two suppliers have already developed solutions for eliminating another common maintenance fluid: brake fluid.
While there are already cars available with brake-by-wire pedals that actuate the brake master cylinder electronically, Brembo’s Sensify and ZF’s EMB take things one step further and feature electrically actuated calipers rather than hydraulically actuated ones. In the case of the former, all four calipers can be specified to feature an electromechanical mechanism that clamps the pads to the discs, while in the case of the latter, all four calipers or only the rear calipers can be electromechanical, with the second setup controlling each hydraulic front caliper by way of a separate electronically actuated master cylinder. Contrast this with a traditional brake caliper setup in which all caliper pistons are acted upon hydraulically, and it’s clear we’re soon to be playing in a whole other realm.
So what benefits do electromechanical brakes have in the real world? Well, they promise faster actuation than hydraulic brake solenoids, which should lead to more precise control of each individual wheel. Automatic adjustments can be made at the calipers themselves for weight transfer and differences in surface friction, and threshold braking in seriously slippery conditions can be achieved by computer algorithms rather than by driver skill. Also, since the pedal is entirely electronic, there’s no heavy traditional pulsating anti-lock braking feedback that may scare drivers not used to getting into ABS during panic braking instances. In addition, electromechanical calipers promise to eliminate brake pad drag which should reduce particulate emissions, and they should integrate seamlessly with regenerative braking in electrified vehicles.
There are purported perks for automatic emergency braking, too. ZF claims that its electromechanical calipers can offer a 29.5 feet reduction in automatic emergency braking stopping distance from 62 mph over a standard hydraulic braking system. That could be the difference between changing your shorts and filing a claim, but without further details on how that number was reached, we’ll have to wait on third-party validation.
Oh, and there are some potential maintenance benefits to this evolution of brake-by-wire. Because electric calipers keep the pads clear of the discs in regular operation, it’s possible that pad changes could be a cinch. There might not be a need to retract the pistons if retraction is their default state to avoid dragging the pads on the discs. Also, removing the need for traditional brake lines eliminates the possibility of having, say, a rear brake line rot out after 20 years in the rust belt. It also means that brake fluid flushes on electromechanical calipers literally can’t be neglected (because there’s no brake fluid to flush).
Are there any potential downsides? Well, I could see a few. The first is unsprung weight, as adding a powerful electric motor and mechanism to a caliper is almost certainly a heavier proposition than a few ounces of flexible brake tubing and brake fluid. The second is packaging, because oh brother, these calipers look huge. Sure, they mean manufacturers won’t have to run brake lines, but the sheer depth of the calipers may require compromises in knuckle design and suspension arm placement to achieve sufficient steering angle. I also can’t help but wonder about rats. They don’t normally chew metal brake lines, but wiring? Happens all the time.
Still, so long as rodents don’t find themselves attracted to the cabling, electromechanical brake calipers offer up some interesting possibilities. With contracts already inked as per Automotive News, expect to see these systems appearing in production cars within the next few years.
Top graphic images: ZF
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I am sure after this brakes will also be soulless. Removing fluid removes soul. Remember power steering?
What fluid will get eliminated next?
Lasers instead of wiper fluid?
Blinker fluid.
Switch to DOT7 blinker fluid and you don’t have to change it for the lifetime of the vehicle. Trust me on that.
Aw man!
I wonder if this could help make truck platooning possible since braking times for different vehicles braking seems to be one of the bigger issues.
Each vehicle could compute and adjust the required braking force and then allow the vehicles to operate close enough together to gain all the benefits.
I’ve suffered from a soft pedal in my old Mk2 Jetta, nearly rear ended an old lady just rolling to the first stop sign. I picture a non-electrified pedal would just drop instantly to the floor with no recoil, like there is also some type of electric motor in the firewall providing artificial pedal feel. I’m sure its not really that way, but its what my mind comes up with
This reminds me of a story from America’s Finest News Source.
https://theonion.com/report-average-male-4-000-less-effective-in-fights-th-1819576624/
No
Too bad we can’t go back and read the outraged comments regarding supplanting tried-and-true cable-actuated brakes with that new-fangled hydraulic crap!
Ha! My very first thought when I saw this headline
The safety of steel from toe to wheel!
Also, BMW making power steering standard on the e30 is the end of sports cars forever!
… it’s amazing what you can learn from old auto magazines, I had no idea.
Cable actuated handbrakes? I read a few on this neat automotive website theautopian.Com
On one hand: Solenoid-actuated electric trailer brakes have been a thing for a good long time, and they work great.
On the other hand: software between my foot and the brakes? NOPE NOPE NOPE NOPE NOPE.
Great point. When the article mentioned that brakes could be individually controlled, presumably by a computer, then this plays right into the direction of modern cars full of computers. Those are great until they fail. These electronic brake systems will now require software updates and occasonal expensive computer repacements. Lovely.
And, we can’t have modern automotive techology without… sensors. Lovely. Now there will be 1 or more sensors on every brake mechanism and wires to connect those back to the computer. More added complexity.
Or better yet, subscription upgradable brakes. You want more stopping power? Subscribe to the premium plus safety package with reduced lag time and increased clamping pressure along with AI-powered airbags and smartbelts the latest advancement in seatbelt technology.
Remember when your steering system would start needing repair about 6 or 7 years in?
Whether it was the pump, the fluid, one of the lines, the drive belt, or the rack, your steering system needed maintenance.
When it failed, whatever oil your car dumped on the road would soon get washed into your local waterways, eventually becoming part of your local fish.
At the point of failure, you would also have the pleasure of losing all steering assist as you veer your car to the shoulder.
Since the advent of electric power steering, with it’s computer and many sensors, we’ve pretty much forgotten about all those shitty problems.
For me, just once in 65 years on the road.
So this means if the electric system shorts out while doing 60 mph, you end up without any brakes and no steering?
Sounds great…
(I don’t say this will happen often, but when it happens, shit will hit the fan)
No, this is not a thing that happens with electric steering systems. We’ve been using these systems for about 20 years, and there’s a reason you haven’t heard much about them. In the very unlikely event of a failure, the system would revert to non-assisted mode just like with a hydraulic system.
I’m not sure what the failure mode would be with this electric brake system, but in the event of a complete system failure (exactly like a master cylinder failure, air in the system, etc.), you would use the emergency brake.
Not sure if pulling the emergency brake does much when going 70 mph on the highway or going down a mountain. At least nearly all emergency brakes on the cars I drove were weak as a noodle. On top of that they’re often on the rear wheels so even IF you could lockup the rear axle with a powerful emergency brake then you’d only cause a spin ; also not great on a highway or going down a mountain…
The point I was making is that hydraulic brakes can and do fail in multiple ways, and a complete brake failure would lead to using the emergency brake, whether the brakes are electric or hydraulic.
I agree with you though that total brake failure is a bad thing.
And just be happy that the emergency brake is only on the rear wheels. Imagine a powerful emergency brake on the fronts only? The wheels would just lock up, causing the vehicle to flip end over end.
Uh but if your front brakes lock up then you get understeer and you go straight, right?
Rear end lock ups lead to oversteer/spins.
But no matter what – this leads to a question – IF the electric system fails which would operate the electric brake (on any wheel/axle) – HOW would it avoid a lock up – would ABS still kick in ? But how can ABS actuate an electric brake without the electric system working? Actually wheel speed sensors wouldn’t work neither so ABS cannot even work without power.
Meanwhile a human could easily brake with hydraulic power, with or without vacuum.
I love technology and I do see a future where most cars are using self-driving, connected with other cars, to form something like a train so traffic jams would basically not be possible anymore, but stuff like electric brakes … Sure they will work fine when the car is new but after 5, 10, 15 years? Good luck changing parts also after 15 years when the electronic world has replaced its whole inventory already about 3 times.
It is like finding a new SAM module for a 15 year old Mercedes – they are there .. And they will cost you like $1000 each. For a module which controls … the LEDs in your rear brake lights…
I guess what you’re saying is that you believe that hydraulic brakes will be safer in an emergency situation, and we don’t know enough yet to make that call.
All I’m saying is that if it’s anything like electric steering, there’s the potential for a dramatic increase in reliability.
Pretty much everyone who has owned a car has had a brake issue. Brakes don’t have to be a thing that requires maintenance so often. There’s so much room for improvement.
I hope I am wrong but my common sense / logical thinking says that an actuator (the electric part) close to a red hot caliper, exposed to the elements, vibration and what not, is prone to fail. Much more so than a simple piston and a hydraulic line.
What fails in brakes is the brake booster, master/slave cylinders etc and those often fail due to neglected maintenance. You cannot see if an actuator is on its way out, those things tend to seize suddenly.
A few other things that commonly go wrong with hydraulic brakes:
Lines
Sliders
Calipers
Hoses
Wheel cylinders
Rotors
Pads
I repair braking systems all the time, and I work in an industry where newer technologies are tested in extreme conditions in the real world. I’ve been doing this for decades, so my beliefs are knowledge based.
Modern electronics can be made to be extremely robust, and suppliers like Brembo and ZF aren’t playing around when it comes to components slated for production.
We’ll just have to wait and see how these work out I guess.
“Remember when your steering system would start needing repair about 6 or 7 years in?”
Nope.
As a parts guy in the 90s, I sold power steering components of all kinds to customers everyday. Not mechanics, just people trying to get to work on Monday.
The vehicles were generally 5 to 10 years old, as that was the lifespan for an average Canadian vehicle back then.
Nowadays, I repair hydraulic steering systems on heavy vehicles on a weekly basis. They are a disaster.
Anyways, whatever you’re doing with your power steering systems, keep doing it. Or get your memory checked out by a professional.
I have an ’06 Honda I’ve owned since new. The only PS work it’s needed in that time has been to replace leaky O-rings in the pump, a pretty common fail, and replace the fluid since I was in there anyway. The rings were a couple of bucks, genuine Honda fluid a bit more and thanks to YouTube the work not too difficult even though I had never cracked a hydraulic steering system before. My ’10 Mazda has needed nothing, ever. It doesn’t snow here so rust is not an issue.
“whatever you’re doing with your power steering systems, keep doing it”
That would be paying them no mind. Which I am happy to continue doing.
LOL
I told you to get that memory checked.
“That would be paying them no mind. Which I am happy to continue doing.”
No. That’s not what you’ve been doing. You’ve been repairing your hydraulic steering system when it inevitably fails, and the fact that you had a failure in your ’06 when you don’t even have snow there is even more telling. If you lived in the snow belt, you would have had significantly more PS failures.
I live in the snow belt, and my ’06 RAV4 has never had a PS failure, and it probably never will, because it’s electric.
Um OK dude. One very minor repair in 18 years, an easily replaced set of O-rings and fluid not a $$$ steering rack. No jacks, no specialty tools needed, just a couple of basic hand tools. There was no catastrophic failure, no complete loss of assist or God forbid all steering control. If I get another 18 years out of those O-rings I won’t complain. I’ve had more problems with the unassisted steering systems on my older cars.
“I live in the snow belt, and my ’06 RAV4 has never had a PS failure, and it probably never will, because it’s electric”
Good for you, you’ve made it this far. As to the future only time will tell. I’ve seen many an electrical system destroyed by rodents. Not a worry for me though, rodents tend to leave hydraulic systems alone. Fuses blow, sensors fail, control modules fry, salt corrodes, rubber rots, potholes exist, A lot of things can happen even to electric power steering.
Good luck with all that.
Duuuude.
Thanks for teaching me that electric things can fail.
The more you know.
Air braking systems have springs that activate the brakes when air pressure is lost and use air pressure to counter the springs under normal operation. They should build similar redundancy into systems like this one.
That should be really fun if one wheel get’s activated after clipping a wire, but running over something on the the highway. Instant “Code Brown!”
Why do people think the wiring for this or any other critical electric automotive systems are just going to be dangling under the car like some halfass stereo install and not instead encased in very heavy shielding?
Because that’s how they’ll leave it after the first time they shadetree their own 15-year-old hooptie?
Because we can all see the Nissans when we drive with literal wires hanging of one or more ends of the car and multiple body panels missing.
Safety systems 101 is designing them to fail in a safe state. Electric brakes would almost certainly retract when energized and extend when de-energized
So there is some heavy duty spring loaded action in those electric brakes?
Because without juice, there isn’t much going on.
I’m not an engineer on the project so I have no way of answering that question. Most likely there would be something along those lines though as long as the system is designed by someone qualified.
I work in electronics manufacturing for less critical applications and troubleshoot failing components on the daily.
Much like people working in tech vs techbros, I trust electronics only as long as I’m within reach of a hammer or a .357.
If this choice bit of stupidty went through though, I would not be above starting a side gig as an expert witness on electronics proving why it was bad for safety-critical applications.
I keep the laser printer next to the gun safe for a reason.
It’s similar to the 737 MAX fiasco – software is fine when it works. And not when it doesn’t work. I love software – it’s my job – but you just cannot keep it without bugs and make t work 100,00% during unforseen situations. Planes will fall from the sky (as they did) and cars will crash (as they are doing even with all the well-meant safety assist we have right now).
Say goodbye to sub $100 rebuilt calipers. Replacing a electronic caliper will cost as much as a whole brake job.
Not necessarily. It depends on how it’s built. My rears have electronic parking brakes (which is super common these days) and the calipers still cost roughly the same as the previous generation vehicles that had cable driven parking brakes.
Nah. This is way different than an electronic parking brake.
Sure it’s different. But it proves that the method of how the caliper works was completely changed, and yet the price stayed relatively stable.
How anyone can so conclusively say this is going to drastically increase prices, is just silly. It might. It might not.
…or a $3 caliper rebiuld kit that has 1 seal and 1 dust boot. Much cheaper than a rebuilt $35 caliper if one can do the work.
I would bet one of the main drivers for this is that the cost will actually go down. If it was to go up significantly, this will just stay as tech for high end super cars but if the idea is to go mainstream, this will drop substantially with scale.
What if this means you don’t NEED rebuilt calipers?
Considering how numb and disconnected Toyota brake have been since (checks watch) “forever”, I’m sure they are eager to adopt this system and remove any last possibility of authentic driver feedback.
When the weather is nice I drive an old school vehicle; no ABS, no traction control, mechanical steering with power assist, and boosted brakes. Not 100% free from aids, but not far off. It’s a very analog experience and you can feel absolutely everything the vehicle is doing.
I’d be very hesitant to move to a full electric braking system. One computer error, a degraded caliper piston position sensor signal, or just a loss of power means no braking. At least with a hydraulic system I can engage leg-day and get to a controlled stop. Some systems should just always have mechanical redundancy.
As soon as brake by wire was the move, electric calipers became the obvious answer. The advantage of fluid is that it transfers pressure feedback right to the pedal, as soon as you’ve added one electromechanical actuator, having 4 only makes it safer. Not only do you get all the performance benefits of individual wheel braking and millisecond-precise antilock systems, you also get the benefit of redundancy. A failed actuator would leave you with 3 wheels still working just fine, and multi-piston calipers would mean any one failed actuator only decreases braking efficiency on that wheel, which the system could detect and compensate for.
2 concerns are that it’d eat up battery range on EV’s (at least when going for a spirited drive), mitigated by the fact they’d probably stay off most of the time due to regen, and the possibility of a dead control module bricking one’s brakes, which sounds pretty spooky to me.
It’s really exciting as an engineer. As a driver, I like hydraulic feedback and manually threshold braking.
The redundancy you described actually makes me feel a little better. I’m not sure why I didn’t realize that.
I’m very skeptical of this, but, then I think about Sim racing drivers and how they are able to transfer those skills to the real track, so, the converse should be true, I think. Going from hydraulic to brake by wire shouldn’t be much an issue if a sim driver can jump in a real car and be competitive.
Afaik nearly every modern car has 4 separate systems for braking – so even if a brake line to one wheel fails – the other will do just fine (and likely the ESP will manage to keep the car on the road since it has 3 wheels to work with).
Will BMW make you subscribe?
Even worse: “We have detected above average use of the vehicle’s braking system over the last 30 days. $15.29 will be deducated from your account.”
“You are about to crash. Do you want to buy the anti-crash protection system v2.0, now, or after the crash?”
Hydraulic brakes still work if the car’s entire electrical system fails. These, not so much. I guess you could use capacitors or something to create redundancy, but this seems like a solution to a problem that doesn’t exist.
Meh, if you lose electrical power you can lean on the electric emergency brake
I suspect the system will be designed that the power off/loss setting is full application of the brakes. Power would be required to release and modulate under normal use.
Mechanically it would not be that different than the air brake system on semi trucks. Air pressure is required to release the brakes and any leakage or failure sets the brakes.
So if an electric gremlin hits you at 60 mph, your brakes will go full on, on the highway? Sounds fun.
Electrically deployed parachute. FIFY
How often to modern cars lose all electrical power? Especially with EVs which also use the motor regen to slow down/stop. I can’t recall the last time I had a car actually die on me, it’s at least been over a decade, of course I keep up maintenance, but if lack of maintenance is the main factor, then the hydraulic brake system would get the same neglect.
Also, Hyundais don’t count 😀
True. They are rolling electricity generators and a failed alternator provides plenty of feedback that it is failing.
My old school alternator failed after driving 3 minutes, about half a mile and luckily, while doing 20 mph AFTER passing a busy intersection. But dead it was and the car had to be towed. The car did NOT keep running since the electrical system just didn’t get any power – even though the battery was fine.
In an EV this might be different, but electric systems in an EV sometimes still need a normal small (12V) battery to run. E.g. a Tesla has a 12V battery to open the doors etc.
Since the chance is LESS that you empty your 12V battery, in a Tesla, than the main battery pack (e.g. by driving and just ignoring the warnings, until it’s 0%) – I suspect electric brake systems run of that 12V battery.
So if that battery fails, due to a short, a broken wire or something similar, then you’d be without brakes.
Yes, if the circuit fails, everything running off it fails, but that doesn’t happen very often even if it recently happened to you.
My point wasn’t that electric brakes will be fine with no changes to architecture. My point was that cars roll, and they can easily produce electricity because of it.
Yes well but they won’t produce electricity if the alternator is dead (VRM /regulator module burned out while driving). Again, for some reason, even with a charged battery, the car just stopped driving (ignition stopped working). I don’t know why. The started worked fine. But the car just didn’t want to start up any more.
Vacuum works as a nice force multiplier, even when there is no ignition (IIRC, not an expert on brake systems here), so as long as the car is rolling (engine is turning) there is vacuum (well, just a lower pressure, not really a vacuum). And that feeds the brake booster. So you have power assisted brakes. And without vacuum you can still operate the brakes – you just have to push the brake pedal much harder. But you will stop.
Without electricity … electric brakes .. do they have vacuum or springs to brake on their own? How strong will the braking power be? Full emergency stop or weak like a parking brake? Will it be enough to save your car when going down a mountain, or driving 70 mph on a straight?
Are the reliable brake booster and those brake lines and the typical caliper really so problematic that they need to be changed? It really feels like a forced solution. A solution looking for a problem.
Oh believe me, I am as skeptical as you!
Yeah, to me that’s not surprising. The battery isn’t the component to do that.
To me, no. The “problem” is not a mechanical one but a financial one. OEMs want more margin out of a car, new products have higher margins. Old products have lower margins. Brembo and the OEM get more margin with a new solution.
Throw dodge in there, I got a phantom drain that drained it 3 times in 6 months.
I imagine they would have to be fail closed like air brakes
Currently sporting electric brakes since sometime in 2009, for many of the same reasons listed above: the Boeing 787.
These days, I never know if using Boeing as the yardstick is to demonstrate something good, or something horribly stupid.
They should make “brake by magnets.”
That would piss the Turd off bigly.
That’s regenerative braking.
I wonder how the brakes would handle something like track use under very high temperatures, and if the brake pedal itself will provide any feedback
What percentage of new cars get tracked?
None, it’s just something I’m curious about. The second gen NSX has brake by wire with force feedback, but it works so transparently, that people don’t complain about how it feels
You mean like going down … a mountain?
Are you suggesting car companies don’t plan for that very real situation?
yes
Then you would be wrong.
https://www.sae.org/standards/content/j1247_201405/
I don’t want to spend $125 on a recommended standard document, if you know what is inside, does it tell what will happen with electric braking systems when the electric system powering it will fail when you’re going down a mountain or doing 70 mph on the highway?
The very fact that there is an SAE standard for “Simulated Mountain-Brake Performance Test” run counter to your suggestion that car companies don’t consider “going down … a mountain” in their designs.
“This SAE Recommended Practice”
Oh goody, more unintended corrosion possibilities!
I’m a little leery of any kind of braking system innovations, given that I work at a BMW dealership and see non-stop recalls for the integrated braking system control module. Somehow I feel like adding even more electronics to the mix isn’t a great idea.
I’ve never had a hydraulic system actually fail to stop a vehicle. I’ve had leaks that needed to be fixed, boosters that have died, but never had a vehicle with total brake failure. If every computer, chip, sensor, and wire on my vehicle were to suddenly fry all at once, I can still steer and stop.
“I’ve never had a hydraulic system actually fail to stop a vehicle.”
Older 1 pot master cylinders would like a word…
Which is why the industry moved to 2-chamber masters.
Chevy uses a sort of Brake by Wire in their EVs and Volt. They still use traditional brake lines but the pedal is electronic. They’re super reliable
As long as my iPhone flushes my toilet.
I’ve been to Japan recently, and their toilets are more advanced than their phones. It is a bit strange in that regard.
Japan has been in the Year 2000 since 1970
Perfect.
Just keep a cable going to at least one or two of the rears for backup and I’m not entirely opposed. And make sure the pedal feel isn’t absolute shit. Hydraulic brakes are a failure prone pain in my goddamn ass, if executed properly, this would be great. Still a hard no from me on steer by wire though.
But we already gave up manual cable parking brakes years ago, so I would not count on any system with full electric braking to include a manual cable and drums inside the rotors when “a few lines of code and a cheap button will do that just as well for $150 less per vehicle.”
Personally I am not comfortable trusting my life to electronic braking. Seeing weird electrical stuff happen in multiple modern cars and still remembering that the Hummer EV had malfunctioning brake lights which at this point we as a species should have NAILED DOWN leads me to not want to take that gamble. Bare legal minimum should be a real handbrake physically connected to the brakes if all else is electric.
Yeah, if a nuke goes of the EMP will bork the brakes.
If a nuke goes off we may have bigger issues going on..
I am guessing Hugh understands that.
I’ll give Cool Dave the benefit of the doubt and posit that he has a similar sense of humor to mine.
I’m pretty sure the electric power steering in my vehicles is a self contained electric powered hydraulic pump mounted on the steering rack. So no changeable fluid, but it’s still there.
No, probably not.
https://www.firestonecompleteautocare.com/blog/maintenance/electric-vs-hydraulic-power-steering/#
That’s what I get for thinking!
The assembly plant folks will like this a lot eliminating fluid additions on the line.
We got some bon bons when we started providing pre-filled automatic transmissions.
Power steering conversion to electric was similar.