Come to think about it, pneumatic tires have been around for over 100 years too, time to let go of the past you know. Surely something must be better, after all, they used them 100 years ago, that just has got to mean there is something better.
And speaking of wheels, those were used in the horse and buggy days, why hasn’t anything better been found? It’s been hundreds of years you know.
we still use the same basic friction brake principle for parking brakes, and we don t call them emergency brakes so the makers won t get sued if they don t stop the car in an emergency, which they would except that most of them don t work because of disuse, because most cars are automatics now so they seldom have there parking brakes used.
how s that for a sentence! ?
and hammers have been around longer than any other tool. no more hammers!
@wesw Junior Grease Monkey10:37PM
and hammers have been around longer than any other tool. no more hammers!
I suggest upgrading to cordless hammers.
lol, don t you mean retro grading? my cave people ancestors used cordless hammers, they called them rocks tho…
Some folks like their cordless hammers and the replacement for the pnuematic tire assembly is in the works-Kevin
However, drum brakes are more prone to fading when hot, because when hot the drum expands, making it more difficult to apply sufficient pressure to the surface area.
“For every complex problem, there is an answer that’s simple, clear, and wrong.” H.L. Mencken
All drum brakes are a sort of power assisted brake, not engine vacuum boost, but the braking torque itself helps to force the shoes against the drum. The secondary shoe receives not only the force supplied by the brake cylinder, but also the braking force of the primary shoe. When the brake shoe’s coefficient of friction is reduced, either by overheating or getting wet, you not only lose the braking due to that loss of friction, but you also lose that self actuation, this compounds the loss of braking.
There is no self actuation with disk brakes, that is one reason they all have vacuum boost, even in small compact cars. Motorcycles do use un-boosted disk braking systems. For that reason, when they overheat or get wet, you only lose the amount of braking due to loss of coefficient of friction, not the compound effect of both coefficient of friction loss and the resulting loss of self actuation.
The absence of self actuation also makes disk brakes very linear and controllable during maximum effort panic stop braking. I remember my first motorcycle with a disk front brake. I could do a stop with the front tire squealing without accidently locking it up. It’s not that the disks were so powerful, it was that they were predictable and linear. Pull on the brake lever a little and it stops a little, pull on it hard and it stops a lot. With drum brakes, pull on the lever a little and it stops a little, pull on it a little harder and the front wheel locks up.
Some road racing bikes used twin trailing shoe drum brakes, instead of self actuation, you had anti-self actuation. You needed Popeye’s fore arms to lock the brake but it was extremely linear and predictable and it didn’t “go away” when wet or overheated, it simply needed a little more force on the brake lever.
I remain convinced that hydraulic brakes are the best solution to the problem. Zero load on the crankshaft, highly controllable, in disc form not subject to staying wet (I remember when, when drums would get wet and take forever to dry out), not subject to becoming useless if the engine dies, highly reliable, and affordable for manufacturers. It ticks all the important boxes. And if power sources cease to be effective sources of vacuum, simply lengthening the lever will compensate beautifully.
As I mentioned earlier, other systems being converted to electric, like power steering, are being converted because they place load on the crankshaft, effectively reducing mpg. Hydraulic brakes do not. They have zero effect on mileage.
You might see electric brakes in the future, but not at 12V. 12V systems simply draw too much current. Kick up the cars buss voltage to somewhere between 42 and 60 volts and many more things become possible and practical. But I still prefer hydraulic brakes for now.
Perhaps in the future we’ll see the type of “air brakes” being incorporated on exotics flow down to real-people cars. That’s a concept that really does work. However it doesn’t help mileage at all.
When something has been around for over 100 years, it doesn’t necessarily mean that the auto makers are “stuck in the past”, sometimes it just means they got it right 100 years ago.
I think B.L.E. nailed it with the above post. Old school or not, hydraulic brakes work very well, are simple, and with very little maintenance and attention, are fail safe. I really can’t see where it would be easy to improve on them. I fully agree with the KISS principle. Why fix something that isn’t broken?
It’s also true that while the principle remains the same, the hydraulic braking systems in modern cars are far evolved from those of 100 years ago. Just the transition from drum brakes to disc brakes was a huge improvement. I drove through that one.
@ “…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.”
Ah, not with air brakes, if you blow a line it basically slamming on the brakes, there is no “glide” to it. Your brakes lock up.
Don’t forget there is water in air, and that water can freeze in the line, which can and has prevent one or more brakes fail. Nothing like have one front tire brake while the other doesn’t. And I take it that all the people saying how great air brakes are, have never used a torch to thaw out a frozen line, generally in the middle of no where, in the dark, in the snow. Or had them fail (as in not working) because they froze up while driving.
" After all Christopher Columbus took a chance…"
And he was lost, BTW most people back then knew the world was round and he was looking for a shortcut.
"Trailers have been using electric braking systems for at least 15 years, probably longer. "
Yes they have, but they only work in one direction. Mobil homes use electric brakes and on one axle they face “backwards” so that you can stop when rolling backwards. They use an electromagnet to expand the shoes and if going the wrong way the lever won’t expand the shoes. I should note that there probable other designs that work in both directions, but the one’s I worked on only worked in one direction.
I only recall one person enamored with airbrakes…
We had electric brakes on a camping trailer when I was growing up. The brakes worked going forward, I think they worked in reverse but maybe not. The intent of the electric brakes were not to stop the trailer but to provide a little drag to keep the trailer from jackknifing on you when you stopped the pull vehicle or were going down a steep hill. They were just there for stability, not stopping.
Mr. Westinghouse was pretty fond of air brakes. Made a massive fortune off them. Also saved many lives as prior to that brakes had to be set manually by a brakeman walking along the top of the train. That was incredibly hazardous. Air brakes started as simple positive pressure systems where you applied the brakes by increasing pressure in the brake line. That worked badly. By the back end of the train there had been enough leaks that there was very little braking force. Also, if a coupler failed and the train was split, you ended up with runaways. Westinghouse improved the system several times until it was where it is today, where a drop in pressure of a certain amount will apply the brakes. The difficulty is that you have to ensure that you recharge the system sufficiently if you have major braking ahead. The Westinghouse air brakes were so good laws were passed requiring railroads to adopt them. I can’t see any reason to use air brakes on a car. On a train or a tractor with trailers it makes a lot of sense. Nothing else can leak all over the place so harmlessly and still provude braking pressure. I’ve always found hydraulic systems quite amazing. They have so many useful properties. But I expect electric braking to be standard when cars have electric motors doing all of the propelling of the car. At that point, adding a little extra oomph for braking will be easy and a lot cheapee than installing a separate hydraulic system.
All the Tesla cars have four wheel hydraulic disk brakes, even though they rely on regenerative braking for a lot of the braking. The boost for the hydraulic brakes on these cars is likely electric just like cars are now going to electric power steering but the force multiplication is still hydraulic. An electric solenoid that can directly apply enough force to brake pads to effectively stop a car is neither light nor cheap.
I have worked on a lot of electric brakes and they go back nearly a century or more. Every elevator is stopped by an electric brake. A lot of electric motors have a brake on them, especially those used for hoists. These electric brakes for the most part use electric power to release the brake. Springs apply the clamping pressure to engage the brake. They are either on or off and function as parking brakes. High speed elevators actually slow down the elevator car using dynamic braking but the electric friction brake holds the car. Usually it’s a great big heavy solenoid that pulls the brake shoes away from the drum.
High speed elevators actually slow down the elevator car using dynamic braking but the electric friction brake holds the car. Usually it's a great big heavy solenoid that pulls the brake shoes away from the drum.
Very interesting! Who would of though that our under appreciated friend the drum brake is used by so many people every day even if they are not fortunate enough to have drum brakes on their car. When your life depends on it such as making sure an elevator stays in place when your getting off, trust your old misunderstood friend the drum brake.