BSA A10 Alternator primary chain cases.

[iansoady]

Yebbut they were made by Lucas and that's what they called them. They should (have) know(n)..........

[duTch]

My first thought was the dynamo on the treadly-cycle, but are they actually AC or DC as the light used to flicker a lot?

 Love to hear that 'Dynamo Hum'
 cheers
 

[bsa-bill]

DC I think Dutch
As for the flicker do you have one leg a bit shorter than the other perchance 
I don't think there was any sort of voltage control so being young and fit in those days I used to be forever blowing tail light bulbs, I also recall some posh types that had a battery (accumulator type ?) in circuit.
I still have a Miller one in the shed, back up system for the A --- no I'm getting silly

[bonny]

Surely the cases are only one part of the equation ? what do you do with the crank cush drive if the rotor is on the end of the crank ? there must have been a triumph clutch fitted as standard to bikes fitted with an alternator.

[duTch]

Back in the '70s I came across an alternator crank, intended to use, but as you suggest Bonny, and due to lack of information->too hard basket, I ended up swapping it for something I could use . In retrospect it may well have been a A65 one anyway tho'. It all seems to be lost or well guarded information for 'need-to-know' basis.
  Bill- maybe the legs just couldn't go fast enough!
 Cheers duTch

[trevinoz]

The alternator is connected to the same circuit as the generator/dynamo via the rectifier and the lighting switch.
The lighting switch cuts in the full alternator when the lights are switched on with only part of it working at other times.
This is the same system used on other makes as a crude form of voltage control.
Thus the two systems run in parallel and is a 6 volt system, not a 6V and separate 12V on the same machine.
Attached are the relevant pages of service sheet 813A.
The first time I saw an alternator equipped A10 was about 1969 in a local dealer's workshop.
I am pretty sure that it had the 1 piece chaincase cover as have B33s that I have seen.
However, all other A chaincase covers I have seen were 2 piece.
The alternator was also available for the A7, there was one locally a few years ago.

Trev.

[chaterlea25]

Hi All,
Theres an A10 bottom end on fleabay that has an alternator rotor on the crank end!!!
I dont know if this is even a BSA crank or not fitted???? seems as if the flywheel is removed or radically lightened???
number 330759188351
Nowt to do with me as usual

John O R

[duTch]

Thanks Trev,
                  Will have a better look after, but the bit that I do suddenly understand, is, why it's 'a closely guarded secret!'!
 Sounds like maybe a primitive kind of relay??

   Had a look at that John, and I say yup, the flywheel is removed, but looks like maybe(?) one of the ones with 6 side bolts as no bolt-hole above the journal where one holds the sludge trap, a bit odd tho'...?