Generator - questions

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2012: Generator - questions
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Leming on Friday, June 15, 2012 - 09:31 am:

I think I read in a prior post, that just because a generator will "motor" when tested, that doesnt mean that the generator is good. I was testing two of my old ones yesterday. both motored off the car, but only one worked on the car - the other one was dead. no output at all - so - they can motor, but not generate?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison on Friday, June 15, 2012 - 09:48 am:

Interesting question. Does it take less amps to get it to motor than and yet though it can motor on the low amps it still doesn't produce enough to put out enough to register. I think I've just confused the heck out of myself. Would a continuity test on the coils and armature give an idea of whether the generator is good or not.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Leming on Friday, June 15, 2012 - 10:09 am:

You cant really do a continuity test on an armature.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Friday, June 15, 2012 - 12:20 pm:

A growler is the only sure way to test an armature taken from a non-functioning generator.

A quality ohmmeter will be needed to test isolation of the field coils to the case.

Same ohmmeter will test the brush plate...insulation will most likely be compromised under the 3rd brush holder and also quite possibly have a high resistance short to the case from oil and carbon particulate.

Once you determine the condition of parts, then you can commence with the repair.

and, "yes" some generators which motor, will not generate.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Friday, June 15, 2012 - 01:26 pm:

Let me elaborate on Scott comments. The Model T Ford uses a third brush type regulation generator. I this type generator the motoring circuit is different from the start-up and charging circuit. The bench motoring test does not ensure the generator will start up on it's own.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Friday, June 15, 2012 - 03:13 pm:

You also can't test the armature for continuity through the commutator. The armature windings are in a wave form and all the coils are connected to each other. Each commutator segment is connected to two different coils in the wave. You could have one coil open or shorted and the meter would still show continuity between commutator segments because of the other coils.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Friday, June 15, 2012 - 03:59 pm:

There are four key armature tests: Commutator continuity (ideally none) to ground, High voltage shorts (ideally none) between insulated commutator segments (as Ken points out, this test can only be conducted with all armature windings disconnected), Growler induced tests for intra & inter-winding shorts (the hack saw blade test) and Growler induced current flow tests of each individual armature winding. Tests 2,3 & 4 requires some specialized test equipment.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Leming on Friday, June 15, 2012 - 10:27 pm:

I have three old generators as junk spares, I guess, My Dad had them in his estate. Anyway, tow of them motor, but he had them marked as "Bad" So, I threw them on the car one at a time and checked, them, and they don not generate. So, I'll rebuild them eventually, I guess, I should have the armatures rebuilt then I will be able to trust them. Does anyone know of a cincinnati area place to have the armatures rewound? (Trustworthy) or Ron, is there someone near Lexington?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Saturday, June 16, 2012 - 10:09 am:

Finding an armature rebuilder in the USA is getting harder to do. I know of only a few shops who do this type work at a reasonable price. You can obtain quality rewound and finished Model T generator armatures from Lang's Old Car Parts.
Ron the Coilman


Posting is currently disabled in this topic. Contact your discussion moderator for more information.
Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration