I have a Briggs & Stratton EXL8000 generator. I keep having to replace the brushes. The "furthest in" brush (black wire) is always breaking and it appears that the casing for the brush melts. What could be the problem?

Sometimes it will work for a month. Other times a few days and even less.

I have heard mention of checking slip rings. Is that what the brushes ride on? Also, what would I check for.

Thanks,

Kevin

The contacs on the armature that the brushes hit might be cutting into the brushes.

I believe the term slip ring would refer to the brush holder, the device that holds the brush in place. The actual brush itself is designed to rub against the commutator, the brass segments around the shaft to which the wires of the armature are connected. Insure that the brush holder is secure and that the brush makes good contact with the commutator. The brush is designed to rub against the commutator, so the only logical reason for heat is poor contact, which would cause arcing. Check commutator for scoring. If scoring is present you may be able to sand out some of the roughness.

Hk:

Commutators are reserved for the permanent magnet DC motor ot the AC universal motor such as you might find in a drill.

In an AC generator (alternator) the rotor is normally just a winding where the magnetic field is changed. The slip ring is the better description, because there are no windings to switchor commutate.

Think car alternator, if you have ever taken one apart.

Here is a picture where someone made a set of "slip rings".

Yes, dirt and scores. The scores could have happened when the springs on the brushes contacted the soft copper of the ring. It does need to be smooth, so sandling lightly with 400 grit paper and cleaning is a good thing.

The brushes need to move slowly within the holder and contact a smooth surface of the slip ring.

I hope you figured out generally how to install the brushes. Either they have brush holders or you have to disassemble the plate where they mount. In the latter case, you insert the brush and then a pin, nail or stiff wire to hold it in place. You re-assemble and pull out your makeshift pin from the outside of the housing.

Thank you for all your help.

We used to take the generator into town for repair when the brushes went out. After two weeks the first time and six weeks the second time, I thought I had better learn how to do it. This is our main source for electricity. On this generator there are 4 bolts for the plastic cover and 2 for the brush holder. Takes 5 minutes, even for someone like me.

I spent the morning getting to the slip rings to where I can see them and work on them. The slip ring in the rear, which is the one that keeps breaking, is worn down on one side a good 1/8 inch. Each slip ring is as wide as two brushes. They look like they are pressed on as well as the bearing after them. I don't see wear Briggs & Stratton sells them separately although someone else might. It looks like they are included with the assembly rotor (part number 194773GS) and I'm sure it isn't cheap.

My question is now if this looks like it's feesable to be able to replace the slip rings by myself (if I can get them)?

I do have a MacGyver move. Since the slip rings are as wide as two brushes. I can go to the hardware store and get the right size spacer and/or washers to move the brushes over. Both brushes would then be on a smooth even surface and would probably last quite a while.

Thanks,

Kevin

I doubt the rings are replaceable. I've been able to machine new surfaces for commutators etc. but 1/8" of an inch is significant.

Save your penneys and have a spare rotor handy M&D Mower -- Search results (http://www.m-and-d.com/search.html?mv_coordinate=1&mv_searchtype=text&mv_matchlimit=20&mv_sort_field=category&mv_min_string=3&mv_column_op=ne&mv_column_op=rm&mv_substring_match=yes&mv_case=no&mv_searchspec=194773GS&x=22&y=11)

Your right, they are not cheap.

You should clean them on a regular basis. The brushes are probably self lubercating. Put an hour meter on the generator and do a PM after so many hours. You might initially try every 6 months.

You are right. They are not replaceable. You also found the rotor assembly $40.00 cheaper than I.

I did talk to a parts guy that said he has heard of moving the brushes out so I will give that a shot while saving money for a new rotor.

Thanks for all your help!

Kevin

He knows what he is talking about.

I found a temporary solution that seems to work well.

Since the slip rings are as wide as two brushes, I did the following:

Taking a used brush holder, I cut off flush where the screws go in, making spacers for the screws (these are as wide as a brush). Putting these on the new brush assembly and turning the brush around backwards brings the brushes out farther thus the brushes are now riding on different parts of the slip ring. I had to go to the hardware store an get screws that were a little longer, I believe 1/4 inch longer (or 3/8 inch, I cannot remember - measure the spacer).

This is a tight fit and a little difficult to put in as the spacers like to move around. Some super glue will help hold the spacers if you have too much trouble but the assembly will go in without it.