The rear brushes of a dual set will wear down faster than the front brushes. The rear brushes may shunt the front brushes thus more current flow through them.
My first motor was a GE-11 that was blue printed by a GE company in Michigan. They v-groove the communtator just enough to take off the communtators bars sharp edges. Then they micro mirror the surface to a mirror surface. This motor was ran from 1976 to 2000 before pulling it out for maintenance. The rear brushes were half the length of the front brushes. This shorten length will cause lower spring tension then the front brushes. I use a WarP 11 spare motor while I have the GE-11 motor in maintenance. I first run the WarP 11 motor non blue printed on a motor test stand to check the running action. The communtator bars had very rough edges and surfaces where you can cut yourself. Run the motor to see what the brush action was, and as I suspected, there was a lot of brush chatter which started to chip the edge of the brushes. I than remove the rotor and V-groove the communtator bars with a V-file and than micro mirror the communtator on a lathe using a fine crocus cloth. Before installing this type of motor in a EV, it is recommended to take and record the ohm value throw the rotor circuit, rotor to motor frame, field circuit and field to motor frame. Normally a brush type motor should read over 20 meg/ohms to the motor frame. In about 10 years this reading could be reduce to 50 K/ohms where it is recommended for maintenance. The problem with a brush motor is that the brush dust tracks from the face of the communtator down on to the motor shaft which causes a current leak to the frame of the vehicle. This is why some people has read a voltage on the frame of there EV even if the batteries are in a isolated non-conductor battery box. Roland ----- Original Message ----- From: "Marcus Reddish" <[email protected]> To: "Jeff Major" <[email protected]>; "Electric Vehicle Discussion List" <[email protected]> Sent: Wednesday, May 08, 2013 9:48 AM Subject: Re: [EVDL] Weird Rear Brush Sparking > Major's suggestions are all pertinent. It seems strange that only one set > are wearing fast and sparking more. Could this be inadequate spring > pressure allowing intermittent contact and thus accelerated wear? > > I will be chastised for saying this, but the only true solution is to get > a > brushless motor. I'm doing that this year, so we'll see how it goes... > > Good luck, > Marcus > > > On Wed, May 8, 2013 at 6:03 AM, Jeff Major <[email protected]> wrote: > > > Hi Mark, > > > > My first thought is damage or a discontinuity to the commutator surface. > > This can be checked with a dial indicator. If found, lathe turning may > > be > > needed. Also check for high mica. The other things to check are all > > electrical connects and spring pressures. Make sure all brushes slide > > smoothly in the respective holders. > > > > Jeff M. > > > > > > > > > > ________________________________ > > From: Mark Hanson <[email protected]> > > To: "[email protected]" <[email protected]> > > Sent: Wednesday, May 8, 2013 7:17 AM > > Subject: [EVDL] Weird Rear Brush Sparking > > > > > > Weird rear brush sparking. > > > > On my 9" Impulse Netgain series wound motor, the rear (towards the tail > > shaft) brushes keep wearing down every 3K miles and sparking. has > > anyone > > had a similar problem and know what the cure is? > > > > Best Regards, > > mark E . Hanson > > in Roanoke, VA > > www.REEVA.info > > > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130508/4002ccb6/attachment.htm > > > > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > > For EV drag racing discussion, please use NEDRA ( > > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130508/dc572ab4/attachment.htm > > > > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > > For EV drag racing discussion, please use NEDRA ( > > http://groups.yahoo.com/group/NEDRA) > > > > > > > -- > Marcus Reddish > > *North Valley Systems LLC* > Stevensville, Montana > 406-360-8628 > northvalleyev.com > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130508/d1a43f69/attachment.htm> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
