Cor van de Water via EV wrote:
Wow, 9000 RPM on a brushed 11" motor? That must be a strong commutator!
Most modern commutators are molded; basically a big piece of plastic with the copper bars molded into it. These are relatively weak (especially when it is hot), so high RPM can be a problem.
Older "industrial strength" motors often had "steel" commutators. This type has two steel rings that thread onto the shaft. The rings have recesses at the outside for the commutator bars to fit into. Mica is used to insulate the bars from the rings and each other. This type is much stronger, and relatively undamaged by high temperatures, and can survive higher RPM.
my previous EV truck had a 13" GE motor with 4000 or 4500 RPM redline. It was overkill to have such large motor and the controller was struggling with it.
That's the "cheap and easy" way to do it. It works. :-) But it makes the motor and controller bigger and heavier.
-- I look for what needs to be done. After all, that's how the universe designs itself. -- R. Buckminster Fuller -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
