Siemens are in the process of developing a new electronic brake powered from the cars 12V supply that applys more pressure the faster you are travelling.
See below.
Is this the only major change to braking since discs were invented ?
www.channel4.com/4car/news/news-story.jsp?news_id=...4
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At first glance, I don't like the idea, because it introduces an element of self servo action to the brakes. By this, I mean that the actuation force needed to apply the brake is partialy derived from the friction force of the brake itself. So, if your brake heats up, and the friction drops, so does the application force - a double whammy.
This self servo effect negates the big advantage of disc brakes - their stability with respect to changing temperature.
Number_Cruncher
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Sounds impressive if they can "stop a car in less than half the distance of hydraulic brakes".
Is this the only major change to braking since discs were invented ?
There are also these radical looking NewTech full contact brakes, which have 75% pad contact area instead of the standard 15%. They are still hydraulically actuated though so I wonder how they compare with those wedge brakes?
There were claims they were going to be used on the Saleen S7 supercar. One of these links says that Renault is/ was evaluating them?
www.carbibles.com/brake_bible.html (scroll down to "Full contact disc brakes")
www.newtechbrake.com/newt/pages/hd22tech.html (bit of a slow website)
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Except that the brakes, however they are applied, will only stop the car as long as the tyres have a suitable grip on the road. My Xantia has the brakes powered by the main hydraulic system so high pressure is always there.
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With all the electrical systems, and associated problems with them, on modern cars the idea of electrically actuated brakes would worry me.
Nothing like having a pipe with oil in it between my foot and the brake disc.
If the cars momentum (presumably rotation of the disc) helps with the application by pushing the wedge "in" what happens in reverse - do they work at all with the movement pushing the wedge "out"? Also what happens when having stamped on the brake you want to lift off before stopping - does it still disengage with the disc still moving?
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I am quite capable of operating standard brakes. Apart from properly set up, unintrusive ABS, I don't want any electronics in between my foot and the brakes themselves.
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Other than the technology involved this differs little in principal from EBA, in fact IMO EBA is more logical because it reacts based on how hard the driver applies the brakes rather than how fast the vehicle is travelling. After all you often need to stop quickly from 20mph and to only slow gently from 80.
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Something similar to this was introduced in about 1989 by Suntour for mountain bike brakes. I had a setup using this, the brake featured a cam that dragged the brake on harder as the pad was pulled forwards by engaging with the rim.
It did indeed increase maximum power, which was much needed in the days before decent pad compounds, v-brakes or discs, however it also removed most of the rider's ability to modulate the brakes accurately, was a bit unpredictable in the wet, and didn't work at all going backwards. It was quietly dropped within a couple of years IIRC.
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You can ride a bike backwards?
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No, but it's a bit of a s od if you don't make it up something steep and then can't prevent the bike sliding back down again.
I can, however, ride sitting on the handlebars facing backwards. Not a skill that has served me particularly well in life I'll grant you.
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