@B.L.E., a permanent magnet alternator has no brushes or slip rings.
It needs a different voltage regulator design because its output voltage rises with rpm.
Behaves like a conventional alternator at “full field”.
I am just going to say it, hydraulic brakes are old technology. Proven, but antiquated.
Hydraulic brakes, The bad, the ugly and the down right terrifying truth-
1.Brake fluid absorbs moisture and requires changing every two years for optimal performance,
2.It damages paint,
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If you burn brake fluid one of the byproducts is cyanide.
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I would trust 15 year old electric wires over 15 year old rusty brake lines. Ever blow a brake line? I have. Its terrifying.
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Rubber brake lines flex and swell, they generally are suspect if they are over 10 years old.
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Braking systems today are a hybrid of old dinosaur hydraulic technology and new space age electronic technology. Lets get rid of the old tech and look to the future.
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Hydraulic brakes are unsafe in case of a failure, they fail and you have little braking ability. If air brakes fail you will stop, electric brakes would be similar if designed properly.
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Brake fluid boils, 10 year old brake fluid boils quicker than you would think.
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In a semi with air brakes you can set the brakes on fire before you will have outright brake failure, the 1992 chevy lumina bombing down the road with the original brake fluid in it is 2 panic stops away from boiling its fluid, boiling fluid= no brakes.
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In a hydraulic system there are no diagnostics, an electric brake by wire could have temperature sensors on each brake actuator to alert you to overheated brakes, sticking brakes ect…
In a hydraulic system if you blow a line going down a mountain you will be in trouble, in an air brake or a well designed electric system if you blow a line or lose a connection you brakes will apply allowing you to safely glide to a stop.
In a hydraulic system everything has to be working to allow you to stop. In an air brake or electric system everything has to be working perfectly to allow you to start moving… Hmmmm… We put an awful lot of faith in our dangerous hydraulic brakes.
Someone cuts your hydraulic brake lines you are in trouble, someone cuts your air or electric brakes lines or wiring you simply will not be able to move. Hmmmm…
It seems clear to me that we need to start using either a well designed brake by wire system or air brakes in passenger vehicles. Keep in mind, we would all be stopping our cars like Fred Flintstone if we didn’t embrace new technology. Our beloved hydraulic brakes were new unproven technology at one time, lets take a chance on electric brakes, After all Christopher Columbus took a chance…
Rick, It sometimes can be a case of the devil you DO know versus the devil you DON’T. And government regulations, which had to rewritten for brake-by-wire systems.
It will take a loooong time to get to full electric systems across the board, especially after recalls for something as simple as an ignition switch.
“Mercedes have done electro-hydraulic brake-by-wire for over 10 years on some cars using a Bosch system with pumps and variable pressure valves”
You’re referring to a system which was discontinued . . . because it was extremely problematic
In plain english . . . it was a failure
Please cite an example which was reliable
@circuitsmith Junior Grease Monkey2:41PM edited 2:49PM
@B.L.E., a permanent magnet alternator has no brushes or slip rings.
It needs a different voltage regulator design because its output voltage rises with rpm.
Behaves like a conventional alternator at “full field”.
There are also conventional excited field alternators that are brushless. Who sez the field coil has to spin along with the rotor? This was used in the Honda sohc air cooled four cylinder motorcycles of the 1970s
I believe that you hit on a big problem with electric brakes @Rick. They must default to locked up. They must operate by forcing the pads to pull away from the rotor by electromagnetic force and applied by releasing the pads to progressively hold the rotor. Any problem would result in instantly locking all four wheels.
@mtb, I’m too lazy to dig up my notes from my aerodynamic course. Look up longitudinal static stability. Stability requires the center of gravity to be placed ahead of the center of pressure of the wing
the Indians figured that out when they put feathers on their arrows… kind of a different subject isn t it?
@chunkyazian Duct Tape Specialist10:27AM
A word about fly by wire. Airliners used to have horizontal stabilizers, the little wings in the back, pushing down slightly for stability purpose. This means the large wing has to support more than the weight of the aircraft, increasing drag. To appeal to airlines with more fuel efficient planes, the stabilizers aren’t design to push down anymore. This fuel efficiency gain comes at the cost of instability. If the pilot lets go of the control, it will oscillate out of control instead of finding an equilibrium. Fly by wire is used to help the pilots keep the plane pointing where they want to go. I don’t know what there is to gain from brake by wire, aside from slightly faster response time.
Actually, “oscillation” is a result of stability. The correcting forces overshoot and then re-overshoot the trim position but the overshoots become less and less and the plane settles down. As the plane gets less and less nose heavy, that stability feedback goes away, point the nose up and it stays there right to stall instead of automatically nosing down in response to lower airspeed.
Also, the tail pushing down is not as inefficient as many believe. The tail is flying in the wing’s downwash, which is like sink to a glider. Reverse the lift direction and the tail is flying in “lift” and is actually recovering some of the energy the wing gave to the air by accelerating it down. A lifting tail, on the other hand, has to fly in the main wing’s downwash and has to accelerate air that’s already been accelerated down even more, lots of induced drag results.
when the internal combustion engine is phased out, hydraulic brakes may be as well rick, but I kind of doubt it. air brakes have a lot more problems than hydraulic breaks in my experience, they are easy to disconnect. that’s the only reason they are used.
cars do not usuaslly fail to stop when they lose a brake line. the front and back systems offer some redundancy as they are mostly separate.
electric brakes must be awfully complicated to be practical. can you imagine a fuse blowing and one or more wheels locking up at 70 MPH on the freeway during rush hour.
your refusal to listen is an alchoholic attitude 
smile buddy. I m hilarious. just ask DB…
Airliners used to have horizontal stabilizers, the little wings in the back
I still want to see all these airliners that don’t have horizontal stabilizers anymore. but not “flying wings” or v-tails.
The biggest problem with electric brakes is mostly how much conventional hydraulic brakes don’t suck. They have a long track record of being reliable and trouble free. Same with canard and flying wing aircraft, their main obstacle is the fact that conventional aircraft don’t suck. You might also say that the inventor of the Wankel engine underestimated just how much the conventional piston engine doesn’t suck.
A lot of failed inventions failed not because the invention didn’t work, but because it was a cure for some imaginary problem with the status quo. A lot of inventors fall into the trap of exaggerating the drawbacks of existing technology.
I fear we have another circular never-ending discussion going again for no good reason. If some manufacturer like Fiat wants to give it a try, more power to them. But all those skid marks on the highway were from semi trailers “safely coming to a stop”? Ever been behind one of those when the brakes locked up on them. Heaven forbid on an icy road. Personally I’ve had more trouble with frayed wires and shorts than broken hydraulic lines.
I dunno though, that’s the great business system that we have. We pay engineers to come up with new kinds of stuff like electric brakes, and then we can fire them when it doesn’t work, doesn’t sell, costs too much, and causes people to laugh at you.
I expect to see electric brakes only when cars have completely electric propulsion systems. Then making the motors also be the brakes is a sensible solution as the car won’t need anything it doesn’t already have. Motors will have to be sized appropriately to both drive and brake, but that’s minor. Diesel and electric locomotives have used dynamic braking for a very long time and use it to brake entire trains if they’re able to. Often they are, on level ground, if they are slowing gradually. They have the big advantage of not using any of the pressure in the air brake system (not applicable to cars) . Hybrids aren’t able to rely on dynamic braking exclusively because their motors aren’t designed for it. They’re big enough to power the car in conbination with the gas engine, and at slower speeds by themselves, but with rare exceptions, they can’t propel the car at full speed or provide strong acceleration. Or decelleration, used as brakes.
Right Guys,no need to reinvent the wheel-one of my friends thought about a fuel cell private plane,but after a little discussion decided maybe His talents were better used elsewhere.Currently ,Him and some really bright Guys are working on some very promising combustion technology-Kevin
Re; the Mercedes Bosch Sensotronic brakes
“Please cite an example which was reliable”
@db4690, I did cite a successful system in the original post; the GM EV1. Yes it was small volume but it was never recalled because of brakes.
Additionally, most all stability control and brake-based traction control systems isolate the brake pedal when they actuate. They essentially are go into a brake-by-wire mode so that individual wheels can be braked to reduce oversteer, understeer or tire slip. The difference between these systems and the Sensotronic is they are intermittent brake-by-wire and use on-off poppet valves rather than full time brake-by-wire system using variable pressure valves.
I don’t believe electro-mechanical brake-by-wire systems will ever be mainstream, the physics don’t work. Electro-hydraulic systems are today’s norm.
It is very rare to have a catastrophic brake failure without any warning. Most hydraulic brake failures start with a small leak, smaller than the capacity of the system so the brakes work, but the fluid level starts to fall. Then you get spongy brakes for awhile and eventually when the reservoir goes dry, total failure.
If you ignore the problem, its not the fault of the hydraulics, it the fault of the driver. Even worse is the drive that keeps toping off the reservoir at an increasing rate as the leak gets larger and still ignores the problem.
With electrics, when you have a failure, it will be sudden and without warning.
keith: “It is very rare to have a catastrophic brake failure without any warning.”
OMG is that true. The last time my brake fluid got a little low because I had the rotors machined, my brake light (on the dashboard that comes on when I apply the parking brake) flickered in the turns when the fluid would slosh to the side. I had no idea I would get a warning light due to low brake fluid until that happened.
Yep in my youth with my Morris Minor, I used to carry a can of brake fluid to fill the master cyl up from the leaks. The brakes still worked though. Now that I think about it, the master was in between the bucket seats inside. I wonder how that worked now?
My Dad’s 1971 Maserati Indy had the master cylinder and booster facing backwards behind the left front wheel operated by a stout lever arm from the brake pedal.