As far as SBC goes . . . they did away with it because it was a problematic POS system, from the get-go
On every model it was ever installed in
Not only that, but you were supposed to replace the hydraulic unit after x amount of operating hours. After that “limit” had been exceeded, the warning light would come on and stay on. And the code would spell out black and white that you need to replace the unit.
There are aftermarket tools out there that somehow “reset” the operating hours.
By the way, after x amount of hours are exceeded, the idea is that the unit is no longer capable of generating a certain pressure. By resetting the operating hours with the chinese tool, your light may be off, but I’m not sure if the hydraulic unit is good as new
All in all, I believe it was a needlessly overengineered system.
Oh, I forgot some things. Even working on them was a chore. Replacing brake fluid required a factory level scan tool. Doing a pad slap also required the scan tool. Sliced off fingers . . .
There are aftermarket tools for this, but they’re pretty much single purpose, meaning they aren’t generally a full fledged scan tool. I suppose you can’t justify the cost, unless you work on these things a lot
As to hydrualic vs electromotive control of airplanes, I recall hearing hydraulic weighs less than an electric motor of the same strength. I can believe it: copper windings around an iron core is heavy!
I think you might find more “hydraulic over regen” brakes out there, even in non-hybrids. I don’t think you’ll see many electric-actuated friction setups.
I just don’t see any benefit to electric brakes as opposed to hydraulic brakes.
The systems mentioned that have gone to electric, like steering, are systems containing components that place a load on the crankshaft. Brakes do not. It could even be argued that electric brakes would add a small amount of electrical draw, and since 100% of your electricity comes from the crankshaft through the alternator, electric brakes would have a negative impact on gas mileage by placing additional load on the alternator that hydraulic brakes do not, albeit a very very small load.
I would not be surprised of water pumps went electric, and maybe even oil pumps (electric water and oil pumps are already available for racing applications), but I just can’t see brakes going electric.
Having spent four years of my life studying and repairing “heavy” aircraft, allow me to suggest that they cannot be compared to automotive systems. “Heavy” aircraft use hydraulics when rapid control surface movement is required, such as the moving of elevators, rudders, flaps, airbrakes, stability control, and other rapid-movement systems. Servo motors are used for those control activities that do not, such as control of trim, elevons, etc. Control surfaces often have a combination of both. B52 bombers even use a third option, a screwjack mechanism, to control their elevons, the elevators being controlled hydraulically. .
As the days of regenerative braking fall into our lap, yes the hydraulic brakes will go the course of the buggy whip.
Even electric cars that use regenerative braking still have conventional brakes, for those times when you really, really, have to stop.
Regenerative braking is no more powerful than the motors that propel the car and even the most powerful sports cars cannot go from zero to sixty as quickly as the brakes can take the car from sixty to zero.
Regenerative braking or not, conventional friction brakes aren’t going away anytime soon, even if they mostly act as parking brakes except for those times when you really, really, have to stop.
I suppose we could use electric brakes in the rear and hydraulics in the front beings that the front brakes do most of the stopping as@Same said aircraft and cars are apples and oranges and there may be some benefit in a hybrid system of sorts,kinda like the awd hybrid system I envision on future 4wd trucks.But on theother hand hydraulic accumulators on Caterpillar Excavators are said to cut fuel consumption by 25%(never underestimate the benefits of hybrid systems)-Kevin
why cant brakes be self bleeding, or are some already?
today when I was replacing the hard brake line to my wheelcylinder (thank god for advanced auto being open) that I wrung off to get my wheel cylinder loose, I noticed, at the tee where the brake line split off to go to each rear wheel, that there was a riser hose coming off of it that went straight up thru or to the floor. it just slipped off and on the top of the tee to each wheel.
I was busy at the time so I did not investigate too far, but what the heck was that soft hose for?
That’s a differential vent tube. That tee screws into the axle housing, right? The bolt that holds that tee down is hollow, and the hose that comes off of it goes up high where it’s not likely to be immersed in water. It should have a little check valve on top of it.
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.
WTH? they don’t anymore? How do they control nose up/down pitch? Please cite some examples besides flying wing types (F-117, B-2) or V tails (old Bonanzas) As far as I have seen, they still do as well as elevators and trim tabs. And the whole stabilizer is adjustable on most if not all commercial air craft.
the little wings in the back, pushing down slightly for stability purpose.
To appeal to airlines with more fuel efficient planes, the stabilizers aren't design to push down anymore.
They actually can “push” down or up “Trim out” depending on if the aircraft is nose or tail heavy.
A properly “trimmed” is more efficient.
If the pilot lets go of the control, it will oscillate out of control instead of finding an equilibrium.
A properly “trimmed” aircraft will not oscillate till out of control, it should just keep flying straight and level, even if the pilot lets go of the controls. Unless something changes such as airspeed. If the airspeed increases it will nose up to seek the speed it was trimmed to, if the airspeed decreases it will nose down for the same reason. Or if the center of gravity CG changes fore or aft, or if bank changes it will affect airspeed and/or pitch. The only way it will go out of control is if the pilot lets it, barring structural failure or the aircraft exceeds its operating limits.
Several brake manufacturers have been working on electric brakes for many years, decades in fact. Delphi even had an electric rear drum brake that was used on the GM EV-1 electric car in the 1990’s. The front brake was a hydraulic system actuated by motors and ball-screw pistons. The brake pedal was disconnected totally from the brakes until a failure reconnected it by using normally-open hydraulic valves. No power, valve opens, brake pedal applies front brakes only. This was done so that variations in re-gen from the braking system wouldn’t give variable braking from a given pedal force.
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. Current Formula 1 cars use a hybrid brake-by-wire system (also electro-hydraulic) because they have hybrid drive systems, too. Conti-Teves had a cool electric caliper that looked very promising 8 years ago but I don’t know if it ever hit showrooms.
Pure electric brake systems have a couple of problems for everyday use. Copper and Steel. Both metals are required in quantity to male such a system work, especially with disk brakes. Both are very large and heavy compared to aluminum calipers with fabric hoses.
Ignore how trailer electric drum brakes work, they will never have the speed of apply or sensitivity needed for car brakes, plus they are drums. Heat and fade, you know.
@EllyEllis: “Well, we had mechanical brakes up to about the 40s, and they didn’t do very well. I think the present system works very well.”
My father’s 1969 Dodge Dart had mechanical brakes, and they worked just fine. I’ll never forget the first time my father took me out for a driving lesson in that car in 1988. When I expressed concern for the lack of power brakes, my father pushed the brakes and locked the wheels, saying, “See? The brakes work just fine. You just need to press harder than you do in other vehicles.”
@Those_who_do_not_see_a_benefit, I can think of a few. You’d never have to worry about boiling brake fluid if a caliper gets stuck. You’d never have to change the brake fluid ever again. You’d also never have to worry about leaking brake fluid, bleeding brake lines, or even checking your brake fluid.
@Whitey - that Dart had unboosted, but still hydraulic, brakes. @EllyEllis is referring to mechanical, push-on-a-rod brakes, something like the mechanical drum brakes on older motorcycles. No hydraulics involved.
Keep in mind some Boeing models and Airbus models are Fly-by-wire, and they work fine.
And every 100 hours those models have to be thoroughly inspected for any problems whatsoever. And every 3,000 to 5,000 hours you have to swap in new engines whether it’s needed or not. And if you don’t comply, you don’t fly.
They also have multiple redundancies - completely separate systems so that if one fails, the thing keeps working. For a car, you’d have to have an entirely separate braking system on top of your electric one.
In short, if you want us to start designing cars like they do commercial airplanes, then be ready to pay out the nose to keep your car legally on the road.
Let’s let the French engineers try it first and see how it works out for them. What’s that saying-French engineers copy no one and no one copies them.
Yep, I had a 69 Dart and I can attest to the fact that it had hydralic brakes since I had to replace all four wheel cylinders. Not power brakes but not mechanical either like on my go kart.