MTFCA Forum

Hello Ladies and Gents.
I’m just in the process of setting up a Generator on a standard 6V. Model T.
I only thought it was the third brush that required setting and planned to set it to about 8 Amps. I have now been told that prior
to adjusting the third brush, you should rotate the complete brush holder (after loosening the 4 screws) and set it to 2 Amps.
Once done and locked up, you rotate the third brush only to achieve the 8-12 Amps
What harm, if any could be done by ignoring the first step? Do others agree with this procedure? Has it been documented
anywhere as it’s not in the “Electrical” Book.
Thank you.
Alan in Western Australia

Hi Alan
Answer is lots, I've seen them do a complete melt down if not set up right,, pull the 3rd brush up so no contact, connect jumper leads up to motor generator, rotate the brush plate to start to motor either way and then lock the brush plate in neutral running, not motoring either way.
Then drop 3rd brush back down. run to set amps then, I do this in my lathe, always have a battery connected as a 3 brush generator will run wild with voltage/amps and melt it's self to pieces.

This will help you. jb
https://modeltfordfix.com/adjusting-the ... patterson/

Alan,

setting your generator isn't rocket science.

After repairing your generator you need to set the "neutral" of the brush bridge.
This should be done as Kerry said.

To check the "neurtal" setting just connect a 10 Watt 6V lamp to the terminal and the frame. Make the generator run on the engine or a test stand with all the brushes connected and the third brush all the way down.

If all is OK, the light should light up (red is OK). If not, loose the four little screws on the back of the generator and move the bridge left or right for a few mm (not the all way) if no light you have an other problem inside the generator (armature, field, shorts on the brushes or ...).
If the light lights up you generator is working.

Now you just need to set the charge current.
Leave the light connected and connect a good Ampère meter between the generator and the battery. You should read about 1A. Set the current to about 4A at a brisk idle by moving the third brush up.
The test light should become bright. After a few seconds you should find about 7V between the terminal and the frame.

Now you can connect your cutout and make the tension and current test again but this time at the cutout terminal.
You should find about the same values.

You can do this the same way for a 12V set up only use a 12V bulb. In the 12V set up you can not use a mecanic cutout because it is closing as soon as your generator output is 7V.
As you stop the engine there will be 12V comming from the battery to the cutout and it will stay closed and will try to make your generator motoring. Attached to the engine it will not run and will burn out. If you are willing to use 12V, you need to build a cutout by using a diode. The diode also work well in a 6V system.

This is just what I learned and use for a few years.
My teachers have much more experience as I ever will have.

Good luck
Andre
Belgium

When adjusting the null point, don't unscrew the 4 screws any more then is what is necessary to rotate the brush plate.

Thank you for the valuable information Gents. Will let you know how it goes. I had no idea about the Null Point setting .
It seems that adjustment is often over looked
Alan

Being a retired electrical engineer I have little faith in 100 year old instruments so in the days before LED bulbs we use to set the generator output by turning on all the lites and then moving the third brush until the ammeter read zero. After all running at nite is not typical use for a T and who has calibrated a T ammeter recently?
JMHO

TonyB did you get my email on the gen system shipping??
POPS

Hello Gents.
Thought I would let you know the outcome of Dad’s Generator in his 1927 T
Your tips were spot on. I used the 6V Battery from another T, found and set the Null Point, fitted a John Regan
6V Voltage Regulator and once back on the vehicle rotated the 3rd Brush until we had 8 Amps. The charge rate dropped down
even lower after 10 minutes. I didn’t factor in the current draw from the headlights as they use about 20 Amps and we
never use the vehicle at night. (By Law and choice) really this was just a matter of gaining confidence and understanding
to make it a simple job.
Even though it said you can set the 3rd Brush by hand with the Engine running without being
Electrocuted I found the heat from the manifolds an issue.
Alan in Western Australia