ADJUSTING 3RD DYNAMO BRUSH

[Paul Nott]

Hi
Could someone please explain how to adjust the third brush to reduce charging out put. Am I correct in thinking the third brush is the top one in the photo indicated by three green mark's. 
Before I go charging in ( no pun intended ) and do more harm than good a little clarification would be welcome.

[Parazine]

The Third Brush is carried on the adjustable aluminium ring on the end of the dynamo, indicated by the blue arrow.


  mag dynamo.jpg (Size: 90.06 KB / Downloads: 253)


Undo the screw and nut indicated by the pink arrow and turn the brush holder clockwise or anticlockwise to adjust the charging rate. You should use an accurate ammeter for this but the panel one will do if you don't gave access to an Avo or DMM. I set mine to 6A, I've had trouble with mag dynamos when turned up to 8A and they're very expensive nowadays!

BTW, the aluminium castings at the end, shown in the photo are very fragile; I had one dynamo years ago where the armature went short circuit at 50mph! The armature was forced out of the dynamo, through the castings, which were ruined. I had to drive back from the Brecon area to Wiltshire with a plastic bag stuck over the hole where I had taken the dynamo out. Advantages of Mag engines!

What's the big jubilee clip for??

[Paul Nott]

Thanks for your answer, very helpful.
Havn't really investigated clip, didn't realise it wasn't standard.

[Robert Leigh]

I suspect the Jubilee clip is to help keep the dynamo in place; the casting is quite often found to be cracked. If you system works why worry?!
Robert Leigh