On 03/27/2010 01:32 PM, Stefan Salewski wrote:
On Sat, 2010-03-27 at 16:28 -0400, Rob Butts wrote:I'm having a debate with an ee friend about how the magnetic resistance works on an excersice bike.May be something like http://de.wikipedia.org/wiki/Wirbelstrombremse http://en.wikipedia.org/wiki/Eddy_current_brake
Yes, this.I've had one apart before - they use permanent magnets and a thin aluminum rotor that's usually geared up from the pedals so it spins pretty fast. To adjust the brake tension a pair of laminated iron poles are brought close to the spinning rotor - the narrower the gap between them, the more resistance. Note that the pole pieces don't actually touch the rotor (except in an old bike I had where the rotor warped from resistive heating - then I got a lot of aluminum shavings everywhere).
Eric _______________________________________________ geda-user mailing list geda-user@xxxxxxxxxxxxxx http://www.seul.org/cgi-bin/mailman/listinfo/geda-user