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Author Topic: No Charge from Aero  (Read 5087 times)

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Offline Manley

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No Charge from Aero
« on: 14 Feb 2005 at 21:01 »
Hi guys, this is my first post so go gentle  :D

I own a 1936 Aero 500 currently being stripped of paint ready for a decent rebuild.  Now, before she was taken apart i discovered that the dynamo a) has a short in the windings and b) has lost all magnetism, so what can i do?  I can re-wind it but its the magnetism bit that scares me.  Im almost at the stage of casting myself a new ring with permanent magnets cast in.  Getting long winded isnt it.  
Also, i found a broken piston ring which i would like to replace, as in replace all as a set, as the bores are good.  Where would i go to get such spares?

Ok, thats my wotsit over for now.     :wink:
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2004 Modified Triumph Thruxton
1986 ME
1972 MG B
1967 MG Midget (Sold)
1936 Aero 500
Not Enough Time to Play

Offline Doug

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No Charge from Aero
« Reply #1 on: 16 Feb 2005 at 03:11 »
Since you say ring when talking about your dynamo, I assume you are talking about the BTH four-pole 'Pancake' dynamo mounted on the timing cover, and not some 'Mag-dyno' retrofit?  It might be possible to re-magnetize this at home if you have a bit of workshop kit.  Even so they do not put out much power when they are in good form so do not expect much!  

The London Douglas Motor Cycle Club's pre-war spares department picked up a large supply of Hepolite ring sets some years back.  They supplied me with a set of +40 rings and pistons for my 1936 600cc Aero.  The stock is much depleted, but you still can get lucky on certain sizes.  

-Doug
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Offline Doug

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« Reply #2 on: 24 Apr 2005 at 03:18 »
I have found some additional information about the output of the BTH 'pancake' dynamo.  The info is given in shaft speed, useful for testing the generator off the machine.  The note on a general arrangement drawings states:

"The generator commences to charge at 1400 RPM or 12 MPH in top gear*, rising to a minimum output of 26 watts at 4200RPM."  

* In the context of a 1926 350cc EW, assumed in solo trim, 6.25:1 ratio.  Note too, the generator was geared up about 2.5:1 (the ratio varied by model) and initially was driven via a cone slip-clutch.  Later on they dispensed with the clutch.  

-Doug
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Offline gordon

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« Reply #3 on: 29 Apr 2005 at 09:24 »
Hi. i have a 1936 500cc aero engine, c/w dynamo, carb, & bth mag, if it is any help. e-mail gordon.hallett@welwyn-lighting.co.uk
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