Jed Rothwell wrote: > Harry Veeder wrote: > >>> Why would there be no brake changes? Electric and hybrid cars have >>> regenerative braking but they also have ordinary brakes as well. > >> Do they mean the braking system did not use friction? > > No, I mean they use the electric motor as a generator, and this puts > a load on the wheels. The electric power it generates is stored in > the battery. This slows the car down, but to stop rapidly the car > also needs ordinary brakes. (I suppose it also needs them in case the > motor fails.)
So the life of the break pads is greatly extended? > >> A frictionless breaking system based on electromagnetic forces >> would be possible but it would not be practical since it would consume >> electrical energy rather than generate it. > > As far as I know it would have to generate electricity. The energy > has to go somewhere. With ordinary brakes, all of the energy turns > into waste heat. I saw a dramatic demonstration of that the other day > driving behind a beat-up bread delivery truck down a steep mountain > in Virginia. By the time we reached the valley, stinking white smoke > was pouring out of the brakes. The driver did not even slow down. I > get a feeling he makes that delivery every day. One of these days he > is not going to stop at end of the road. > > - Jed > > Yes you are right. With strong enough magnets it might even be possible to do away with friction completely, while the separation of opposing magnetic poles could be controlled hydraulically. Harry
