I just can't burn another armature....

D

daltonathomas94

Member
I have a '37 model 77 and I just can't figure this out... the generator the truck came with burned up, the new rebuilt one burned up and now I have a third that I just want to work, I've spent too much as it is.

This new unit is a '33 so I've been told, and I have a new solid state cut out. 3rd brush, 6v positive ground with two wires coming out of the top. One seems to terminate at a brush (PVC insulated) and the other at the field coils (cloth covered towards back). I'll attach pictures to make sure it's all correct if someone can help me out.

Oh, and the rebuilder seemed to paint the bracket on the manifold side. I assume I should clear the insulation so it grounds properly?
7eaec5c0c152725c9c07d778e4338a22.jpg
3b85b90c3365b55953dc367346548eb3.jpg


Sent from my SM-G950U using Tapatalk
 
Here's a picture of the generator in my '34....

Maybe you fried the electronic cutout as well....


400740



400741
 

Attachments

  • '34 Generator 001.JPG
    '34 Generator 001.JPG
    127.1 KB · Views: 255
  • '34 Generator 002.JPG
    '34 Generator 002.JPG
    112.7 KB · Views: 251
Last edited:
How have you positioned the third brush? You need to set it so you're only charging around 5 amps as indicated on the ammeter. Do not run the 3rd brush all the way down.
 
And I don't see any cooling fins on back of pulley; that can't help.
Oh, and welcome to the barn!
 
It looks like I have it wired correctly supposing the yellow wire in your pic is the field coil ground.

Should I start off with the brush in the middle? Is down counter clockwise (looking at the fan)?

Sent from my SM-G950U using Tapatalk
 
Thanks Brian! Happy to be here. There is no venting in the front of the generator so there would be no need for fins

Sent from my SM-G950U using Tapatalk
 
And I've purchased a new cut out. What would be the proper way to polarize this? I'm only familiar with the later models with terminals coming pt off the housing and a voltage regulator

Sent from my SM-G950U using Tapatalk
 
You don't need to polarize the cutout, just the generator. How many amps is it
charging and what is the output voltage.


Bob
 
It looks like it's putting maybe 10? I'm not too sure how ro read this guage. Bit I'm getting a bit odd a high pitched buzzing noise from the comutator when running. It's still bright and shiney so I don't think it's doing any thing bad, but it's concerning. And now I can't seem ro get up passed 45mph and it seems to loose power as I accelerate passed maybe 2k?

Engine is off in the photo. It's at the 1st tick when running with a spike when I hit the brakes. No change with headlights
0e5acb79e19160ee1ade7565d61a2f6f.jpg


Sent from my SM-G950U using Tapatalk
 
Moving the third brush down, ie in direction of armature rotation, increases the charge rate. Start with it positioned just slightly down, run engine and watch ammeter. You want it indicating around 5 amp charge. Move the brush up/down to accomplish this. The engine needs to be doing a few revs in order to get gene charging, say equivalent to 30 MPH highway speed; it will not show a charge at idle.
These generators do not have any voltage/current control. You manually set the third brush to regulate the charge rate. The cutout on top is merely a one way switch; when generator stops turning, the cutout [switch] opens to prevent current running back from battery, which would discharge [flatten] the battery.
 
Ok, that clarifies up vs down in relation to the third brush for me. Would anyone know why it might be buzzing? I suppose it's more of a mild screech, but it sounds like the brushes on the comutator. Or perhaps I'm using the wrong oil (20w motor bearing oil) and I'm just mistaking the placement of the sound?

And unless I screwed up the trans changing the fluid I suspect electrical to be at fault for the loss of power... any takers?

Sent from my SM-G950U using Tapatalk
 
All the information that Brian has given to you is spot on. Your generator is for a 1933 model ford V8 as it has no cooling fan on the pulley and no cooling openings on the front end housing. The rear housing might have holes but I cant see it. The 34 ford has a cooling fan and openings on it. This non cooling of the generator windings inside limits its safe output to about 12 amps continuous. IF you have the third brush pushed down with rotation then it will charge beyond 20 amps and eventually cook the armature. The ammeter on your vehicle is nowhere near accurate enough to set the third brush at which should only be about 5 amps with the engine revs up a bit. Generators do not charge at engine idle speed, they need a few revs up. Find somebody with a good analog automotive generator test set to set your third brush. An auto electrical shop should have one. Your replacement round cut out has a diode inside and wont suffer having the battery polarity connected in reverse. The original mechanical FORD round cut outs are the best. There is a round cut out available which is actually a voltage regulator of sorts and made by FUN PROJECTS, look them up. I have one on my 34 Ford generator and it works very well. It allows a little more flexibility in the charging rate. Good luck. regards, Kevin.
 
All of this is greatly helpful and I thank you all. I have a rebuilder close to me who will do a bench test and set, I'll bring it around and see how that goes. I'll be safe for now and bring the brush up a bit to get it on the road long enough for a few miles. Hopefully I won't get too excited if all goes well and remember to report back my results. Again, thank you all.

Ps. The loss of power was just me forgetting to push in the choke again. I only saw it after looking in the truck to too close everything up for the night

Sent from my SM-G950U using Tapatalk
 
The new brushes in your gen are making a noise because they are not bedded in on the commutator. Take a strip of very fine sandpaper ( not emery ) and carefully with your finger run it on the commutator with the engine at idle speed. You might need to do this several times. Watch your fingers. Regards, Kevin.
 
If you are using a Fun Projects electronic voltage regulator in place of an original cutout, I'm reasonably sure their instructions suggest moving the third brush as far as it will go in the direction of armature/commutater rotation. to give the maximum output, and let the regulator establish the necessary output based on the needs of the system, I've had mine setup per their instructions for the last 32k miles, and it has worked like a charm.

Correction to above information..... Fun Projects instructions for setting position of third brush are actually as FlatheadTed describes in his post #18 below. In my case, I did have to set the third brush for high current output because of the halogen bulbs I use, and other high current draw components on my car.
 
Last edited:
JM 35 Sedan said:
If you are using a Fun Projects electronic voltage regulator in place of an original cutout, I'm reasonably sure their instructions suggest moving the third brush as far as it will go in the direction of armature/commutater rotation. to give the maximum output, and let the regulator establish the necessary output based on the needs of the system, I've had mine setup per their instructions for the last 32k miles, and it has worked like a charm.
Click to expand...

True, that is because it is a voltage regulator. This applies only to the Fun Projects "cut out" and not to other cut outs.
 
The last fun project I did came with these instructions that's mainly covered by others here.,,
(1)Start the engine move the 3rd brush counter clock wise as viewed from the front ,
(2) turn on all the accessory's with the motor revved up move the third brush in the direction of rotation clock wise until the Amp meter shows 1 amp charge ,that's in a up ward direction as viewed from the front ,
switch of the accessory's and observe the charge rate should be 7to 9 Amps ,it should never exceed 10 Amps,
 
Last edited:
You must log in or register to reply here.
Back
Top