Interesting how folks want electric brakes, when I know of NO working example of 100% electric brakes on a car. Is there one?
Me neither. None that I’ve ever heard of.
When did “Will we ever do away with Hydraulic Braking Systems?” morph into “(we) folks want electric brakes”? Who said they want electric brakes?
I’ve pointed out what I think would be some advantages, but I don’t particularly favor one over the other. It’s like the timing belt debate; both options have advantages, and I’d prefer the more reliable of the options, but I’m not going to commit to one or the other until I consider the entire vehicle.
Truthfully sojourners,a hydraulic or mechanical system for brakes work extremely well at low speeds(the brakes seem to last forever at low speeds,but speed things up considerably and brakes wear very fast it seems the dynamic braking systems do have a definite advantage at high speeds,a considerable retarding force,with little wear on componets an electric locomotive is a good example and consider how good the “Jake brake works on a heavy truck” I drove a Mack over 200K miles with very little wear on the service brakes and it was mostly a heavy duty cycle,but make no bones about it the kinetic energy is converted to another form of energy(usually heat) either by friction or dynamic process as some of these Guys have pointed out there maybe some other advantages in a electric breaking system as well-Kevin
With all due respect to everyone, I think we are stuck on the idea that braking is only done by the “brakes”. I see engine braking incorporated more and more as it is in hybrids now. Maybe it’s because I drive a tractor and never use my brakes…ever. They are just used as a parking brake. As soon as electric drive motors are the norm, we WILL have electric braking. Steering by wire is just around the corner now. It sneaked up on us and within ten years, it will be in at least one or two models of all makes made. Actual electric braking will be in @samemountainbike. 'S lifetime…because I see him living a long and healthy life. Servo controlled electric braking will also be here on some cars within ten years, maybe sooner. If it’s not, the first round is on me. Servo controlled electric braking will be more reliable then hydraulic braking and more functional. Hydraulics have been replaced by electrics in a lot of other uses. It’s just a matter of time.
If by “electric brakes” you mean energy recovery braking, then yes, it will be on more and more cars, however, even the Prius which is designed to use energy recovery braking as much as possible still has four wheel hydraulic disk brakes, as do the Tesla cars.
It’s not just for parking and low speed stopping, there’s a limit to how much power an electric motor can absorb as a generator and a limit to how much power a battery can accept from that motor. While perfectly adequate for normal slowing down when driven by people who don’t insist on racing towards red lights, when a deer suddenly jumps in front of your car, you will need those old fashioned friction brakes.
Consider what the brakes on a 2014 Corvette have to do to perform a 107 ft. 60mph to zero stop. (the claimed braking performance for that car) The car weighs 3300 pounds so at 60 mph it has 399,300 ft. lb. of energy that the brakes have to absorb in only 107 ft. That’s 3,731 ft. lb. of energy for every ft. traveled. At 60 mph, 88ft per second, that energy is being absorbed at a rate of 328,396 ft.lb. per second or 597 horsepower. Even on a ridiculously overpowered car like this, the brakes are more powerful than the engine is. The sixty to zero time is shorter than the 0 to 60 time.
In normal cars, the brakes are way more powerful than the engines/motors are, because most of us can live without going from zero to 60 in 4 seconds, but going from 60 to zero in that time is not a luxury when an emergency arises. With dynamic braking, the braking is only as powerful as the motors are. That’s why both Tesla and Prius kept the conventional disk brakes even though they both use dynamic braking.
As for hydraulics, you have to remember that the hydraulics don’t power the brakes, the driver’s foot does, with a little help from the power brake booster, or no help at all on most motorcycles. The master cylinder piston and the caliper pistons amount to a “long lever” in multiplying force. Also, even if the engine dies and the electrical system’s fuses all blow, the manually operated hydraulic braking system can still stop the car, you have to step on the pedal a little harder but you can still stop.
For that reason alone, I believe the hydraulic disk brakes we know today will still be around for a long time to come.
“Who said they want electric brakes?”
Unless I’m completely misinterpreting the situation, I believe Rick wants electric brakes
In that long list of drum brake advantages from Wiki, surprisingly, they left out the one advantage that matters to people who are trying to set gas mileage records. When not in use, springs pull the shoes away from the drum and the brake totally freewheels. With disks, there is always some residual brake drag when not in use. The piston stops pushing but it doesn’t pull the brake pads away. This makes disk brakes inherently self adjusting, in fact, disk brakes will let you know that the pads are nearly worn out if you check your brake fluid level in the master cylinder. When the fluid level is close to the low mark, you likely need new pads. When you install the new pads, the brake fluid reservoir is full again as the caliper pistons go back to the unworn pad position.
Because springs retract drum brake shoes, drum brakes need some sort of adjuster to take up the free play as the shoes wear or else the pedal goes nearly to the floor before the brakes engage. Most of them had automatic adjusters and the brake fluid level in the master cylinder reservoir stayed constant as the brakes wore.
Why not put em’ in the rear and leave the hydraulics in the front? Beings the front brakes do most of the stopping,dynamic brakes can absorb tremendous amounts of power,engine brakes are rated in hundreds of horsepower and the dynamic brakes on locomotives run their excess power through a disapater of some sorts,in Europe electric retarders for smaller trucks have been availible for years (my first suggestion would give some the redundancy they crave[which makes sense,driving is serious business] Enjoyed the benefits of a powerful"Jake" brake yesterday several times on a 15% grade-if I had to relie on the service brakes,they would have soon been overheated and useless-Kevin
From the energy perspective, electric brake doesn’t make sense. Hydraulic brake simply transfers energy from the driver to the calipers. The driver provides the energy for brake actuation. Air brake uses a small fraction of stored energy from the engine. Once the brake is applied, it doesn’t take more energy to keep it applied. Electric brake requires a constant supply of energy going through the solenoid to apply the brakes.
I never said I wanted them either.
I don’t want a tornado to spin through my neighborhood either but that doesn’t stop me from seeing it coming. People may not like the idea so they shoot the messenger in the hopes it will go away…
@ TSM
I never said there was any advantage to the consumer although one might argue some of the finer points are advantageous but in the end, it doesn’t matter one iota. If it reduces costs for the manufacturers, they will adopt them. And I can plainly see how that is possible.
Electric brake requires a constant supply of energy going through the solenoid to apply the brakes.
I see you have a design in mind but your implementation has this limitation.
It doesn’t need to be purely electrical. I am envisioning electro-mechanical operation with perhaps cams and springs that require very little energy to overcome the “resistance” to application. Levers are used in the current systems too in order to reduce the required effort…
The regen braking on my hybrid is (as others have said) a form of electric braking, it just doesn’t handle the last amount (hard to tell how much it does handle). Given the comments on low pad wear with hybrids, regen probably handles maybe half the load. That’s fine with me, but I don’t know of a 100% electric solution for the other half, and the large load required in emergencies. It may be that regen + hydraulic in hybrids/EVs is the ‘sweet spot’ (cost/benefit-wise) for advanced braking. Not much use for regen in a non-hybrid/EV, though.
electric brakes could use levers too, depending on the design. and given a long enough lever I could move the world right? so I think electric brakes could be designed too handle an emergency stop. maybe no current design would do it but…
TT, I don’t have a design in mind. But I do know that a solenoid needs a flow of electric charges to apply a force. That flow of charges needs a electrical power source to overcome resistance in the wire or the flow stops. Any number of mechanism you want to use simply multiplies the force of the solenoid. Unless you use electrostatic actuators, which is relatively weak, applying a force on actuators requires a constant power supply. I would like to have electro- pneumatic on my daily driver, but I don’t see pure electric happening
Wes, how would a longer lever make a difference to electric brakes?
it would have to be a totally different design than you all are talking about, in fact a totally new design probably, but I think you could use electric power to pull a lever just like you can pull one with your arm or a push one with a leg
Using a linear electric actuator with a lever system to operate brakes would be much more complicated than using a hydraulic system. To control the actuator’s extension such that it only extended the caliper lever or shoe lever to the amount requested by the pedal force would require a feedback system with linear sensors that provides a feedback signal that, at a certain brake force, nulls the actuation signal at a certain point in the actuator’s travel. It could be done with a microprocessor taking a signal from a piezoelectric pressure transducer on the pedal assembly, but…
See how complicated this gets?
I never advocated it or said it was better
I was responding to who ever said that electric brakes would never be strong enough to do an emergency stop
theoretically they could in my opinion, easily be strong enough
i did not see that twin turbo had already made the point or i would have just agreed with him, and avoided having my eyes glass over… 