I rebuilt the generator on my 26 TT. On the bench it runs like a motor when I connect a battery and raise the third brush. When I lower the third brush and reinstall the generator it does not indicate a charge through the amp meter. I get about 6.3 volts on the charge side of the cut out, which is the battery charge level. On the generator side of the cut out I get about 55 volts. What's wrong?
I believe your cut out is NOT working. I hope you don't run it this way as you will burn out your generator quite quickly. The T generator should not be run open circuit!!!
Diagnose the cut out
I am not a specialist but some one told me, with the third brush raised, you need to move the brush bridge one way or the other till the generator stop turning as a motor when connected to a battery. Lower the third brush and it will start running as an electric motor again. Set the third brush all the way down.
Re-install the generator, run the engine and connect the generator to the battery with an Amp. meter in the wire without the cutout. Move slowly the third brush up till your amp. meter say 5Amp and block the nut. With a Volt meter between the generator terminal and the ground you will find first the battery tension 6.3V and as it start charging the tension will go up to 7.5V to 8V.
Stop the engine, re-install the cutout and make the same test. If you have no output on the cutout terminal and the tension on the generator terminal is going up to 55V your cutout is open and not working as Les said. Driving that way will destroy your generator.
Maybe this helps.
I work on Model T charging systems every day.
Your welcome to give me a call tomorrow 10AM to 5PM (EST) and I will try to help.
Take Ron up on his generous offer. You won't find a more knowledgeable guy on this subject.
Working with Ron now. He is talking me through everything step by step. He is very generous with his time, knowledge, and experience. I only hope I can return the favor or be of assistance to my fellow enthusiasts some day.
Ron P is one of the best! One of the best people. One of the best electrical engineers (I know, my dad was also one of the best electrical/electronic engineers!). One of the best model T'ers.
We all are fortunate to be able to know him. And many other wonderful people in the model T community.
Drive carefully, and enjoy, W2