Return to Website

Welcome to the Austin Seven Friends web site and forum

To get a quick overview of all the messages click on

" Switch to Threaded style "

Forum: Welcome Austin seven Friends
Start a New Topic 
   Board|Threaded
Author
Comment
Magneto type CAV dynamo

I have not found any articles detailing the secrets of these dynamos. Does anyone have good information they could impart about how to check and adjust these? I have two, neither of which works at present, and the brush housing casting is differently anchored in the slotted holes. I hesitate to change anything without sound information on what I should be doing.

Robert Leigh

Location: just north of Cambridge

Email  
Re: Magneto type CAV dynamo

The best reference is a small booklet by D.G. (Harry) Hales 'The Austin Seven Electrical Guide' printed by Smallprints (no date)

This covers Dynamos, cut outs and switch panels including the 1922-1928 DF and DFL Dynamos and offers some helpful information.

I only have a photocopy of this most useful booklet- someone may have an original with clearer pictures.

Cheers, Tony.

Location: Melbourne. Victoria, Australia.

Email  
Re: Magneto type CAV dynamo

Do these differ much from the DEL? is the 3rd brush adjustable?
With two ball races care is necessary that not preloaded or constrained.
For those familair with more common 2 pole devices the 4 pole can be puzzling, with main brushes at 90 deg. And armature not wound 1 to 2 to 3 but 1 to mid to 2 etc whch complicates tests with an ohmmeter.
The modest output best taken from the no load ammeter charge; balancing lamps is only applicable with original wattage bulbs.

Location: Auckland, NZ

Email  
Re: Magneto type CAV dynamo

Bob.I'm no dynamo expert but my rebuilt CAV dynamo was capable of producing 27 amps unregulated.The third brush is adjustable and the bearing located in the aluminium die cast brush end can slide in the housing.
This light aluminium casting is usually cracked,or the bearing dia oversize.

Re: Magneto type CAV dynamo

Thanks A i S.
That output is surprising but, in the modern jargon, “not sustainable”!

I have done all my own car work on various troublesome makes over the decades. I have no trade background but managed to avoid many of the provoked failures in which many “professionals” seem to specialise.
But I did manage to ruin a bearing on a DEL dynamo....

Location: Auckland, NZ

Email  
Re: Magneto type CAV dynamo

I am also after a copy of this booklet. Does anyone have a copy? Has it been reprinted? Can anyone copy their booklet to the web site?
Thanks in anticipation.

Location: Findon West Sussex

Email  
Re: Magneto type CAV dynamo

Thanks to all who have contributed to this thread. I got enough information to determine that both my dynamos were beyond a quick fix for our trip to France next week. I dipped my hand in my pocket and bought a tested working dynamo.

Location: just north of Cambridge

Email