Dynamo Identification

Hi Stuart,

If you give me the data stamped on the dynamo, I can tell you exactly which make is fitted for, and if you wish, each of the components.

Regards,

Hans.

Hello Stuart....That is a Lucas 3-brush dynamo, with a resistor fitted in the lighting switch to regulate the charge via the 3rd brush.

Miller also produced the 3-brush unit .

I you google "3-brudh dynamo all will be revealed !!

regards .Colin

Hi Stuart,

The data are stamped on the body. In your case, maybe dirt or rust has been covered the surface of the body, which makes the script unlegible.

Using a steel brush, you can see what is stamped on.

Regards,

Hans.

Hi Stuart,

Attached a picture where you can find the data stamped on the dynamo body.

Wait for the reply to help you.

Regards,

Hans.

Hi Stuart,

what make,model, year bike is that dynamo attached to?

Skip

Hi Stuart

I have one of these on my BSA Blue Star. It is a Lucas E3M. I think that yours has the output terminals on the end of the dynamo cover. I believe that this was the last incarnation of the three brush dynamo from between 1933 and 1935. Earlier ones had the leads coming from the sides of the end cover ( I have been told).

I understand that they can be converted to use the later separate voltage regulator which may be of benefit because the voltage regulation of the three brush dynamo is basic.

As Hans has mentioned the data and date (months and last two digits of the year) is stamped on top on the same side as the screw that retains the field coil.

Hope this helps

Colin

As Colin said, you can rewire the dynamo quite easily. I would test the field coil and armature & replace if required. Then carefully remove the coil at the ens of the dynamo cover (shown in your picture). Also remove the 3rd brush. The 2 brushes you have left will be directly across from each other at 180 degrees.

then take your 2 wires from the field coil, one goes to the "F" terminal on your end cover, the other wire goes to the earth screw.

On the two brushes, one goes to the "D" terminal, the other goes to the earth screw.

Polarize the unit, then test by "motoring" to verify direction. If it turns the wrong way, reverse the brush wiring. Test again.

Then I would use a DVR2 modern regulator from Dynamo Regulators:

http://dynamoregulators.com/

which can be used for 6v or 12v, but you must specify if you are going to use positive, or negative earth when ordering.

There are more details to the above directions, but I figured if your going to wait till winter, we can put in a full article on the process when your ready. It is quite easy. I can do some photos, as I often do the same thing for Miller dynamos

Skip Brolund