Hi all,
To start at the beginning, it was during the Centenary Rally last year that the dynamo on the '48 T35 spat the dummy throwing solder and a segment of the commutator into the innards. Within a short while after returning from the ADCR, I was able to purchase a matching dynamo albeit one not in the best of condition outwardly, but the armature at least was in good order so I took that armature and incorporated it into the existing dynamo after carefully checking all other components, refitting the brushes, checking the field and so on. It was declared servicable.
The dynamo was just recently installed on the bike and initially all seemed ok but soon the ammeter needle was seen to swing and vibrate rather wildly and the output slowed to just 1 - 2 amps - finally no output at all was registered.
The dynamo and regulator were removed from the bike and set up on a 'test-bed' (on the mill) where a voltage meter/ammeter showed adequate output which was tailored by adjusting the regulator to desired values for voltage and output - when all was working ideally, the dynamo, apparently in first class working order, was reinstalled on the bike but alas it failed to produce even the dimmest of sparks - the process of removal, testing and reinstalling was repeated twice more before someone questioned whether the dynamo was indeed rotating when installed to the bike.
Eureka
You guessed it - the dynamo was found not to be rotating! The reason? - well, this I think - when it was re-installed to the bike a modicum of grease was applied to the dry dynamo pinion. Apparently this has been enough lubrication to rob all semblance of friction from the friction drive (or spider gear) located within the magneto housing which has allowed the drive pinion to rotate freely without turning the dynamo pinion.
The question is, can someone advise whether or not the friction drive is intended to run dry or does it require to be lubricated? (at present there appears to be a coating of dried grease within the housing in the magneto and perhaps a very small amount of fresh grease is discernible too.) Also, how is the pressure of the friction drive adjusted? - and how much pressure is required for it to operate as intended, i.e., presumably it is intended to have sufficient friction to drive the dynamo under normal operating conditions yet allow it to 'free-wheel' if for some reason there should be some unexpected resistance from within the dynamo, whatever the cause?
BTW, it may be important to note the dynamo ID data. It's Lucas of course - the data reduced to a single string reads, "Mn 2.6 - 460210 - XX1 - 1147" - (the hyphens do not appear on the stamp and the point between the 2 and the 6 is superscripted).
Alwyn
The magneto/dynamo drive sprocket...