MTFCA Forum

I have a "rebuilt" generator that I acquired in a pile of stuff a few years ago and installed it on my ranch car a few days ago. I had set the 3rd brush all the way to maximum and was only getting about 6 amps out it. After maybe 30 minutes of run time, I had nothing showing. The headlights lights pulled 10 amps minus, so I know the ammeter was working. I did a bench test of it, running it as a motor and it did run but was drawing 12 amps. A target of 6 or 4 would be much better.

Upon looking closer at the brush plate, I noticed that the "rebuilder" used paper gasket material as the insulatation. Oh boy...! I happened to have one of Scott Congers rebuilt brush plates on hand so I swapped that into the generator. ( Having done brush plates in the past with those nice fiberglass discs from Fun Projects, that $50 to Scott was well worth it. ) I also lapped the brushes to the commutator with 600 grit paper. Next, went on to set the brush lead ( neutral setting ) with the 3rd brush raised and then tightened up the brush plate. Again, motoring the generator on the bench, she was drawing 12 amps but did spin faster. Just to try it out, I put it back on the car and ran it. No output, even with the 3rd brush advanced all the way.

What should I look at now? While I had the brush plate off I did not do any ohm readings or continuity tests on the field windings. It's supposed to rain all day tomorrow, so she's coming back off.

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Check the cutout?

I removed the cutout and hooked a voltmeter directly to the output lug. No voltage. Is it necessary to "flash" the output lug before running the generator? Scott...?

Dave

Ron Patterson has answered this question before and does such a good job of it, rather than repeat it for you I am going to send you right to it: http://www.mtfca.com/discus/messages/17 ... 1314501499

See: Ron Patterson-Nicholasville, Kentucky on Friday, August 26, 2011 - 02:18 pm:

This is as good a description for adjustment as you will find and it does not require removal from the car.

If this does not perk it up, you have deeper trouble very likely with the armature, so long as you verify good insulation resistance of the windings and the armature is not dragging on a misaligned pole face.

If unsure, take the armature to someone with a growler and check it out. Also be sure to clean the commutator well and ensure it has been undercut properly.

There's a lot to these things even if they look simple!

Thanks Scott. By the way, do you have any more brush plates ready to sell?

Dave

I will have to check

Dave

sorry, no brush blocks in stock

I have by no means any "pro" experience with anything electrical, BUT, I do know from past experience with motor driven welders (read generators), armatures should NOT be dressed down with sandpaper because the grit can cause problems. There are special "stones" that are made for this purpose, I've used them many times over the years on motor driven welders. I'm sure someone much more knowledgeable than me will chime in here. Dave

Read the link Scott posted, esp the part about setting the neutral point.
While this might not apply, was talked about in the linked info; We had a generator that had new field windings in it, no matter what we did, could not get it to work right. Ron helped us get it sorted out. It had the windings that were made wrong and by uncrossing the leads worked great. While I am sure some of the bad windings are out there, the current ones made for the past number of years are OK.