DEL 1929 dynamo

[Parazine]

Do you both have the 90 degree arrangement? It feels to me (without removal - I'll go and scrutinise with a mirror after reading this) that the main brushes are at 12 o' clock and possibly 6 ' clock (180 degrees) with the third moving between 1 until 5 looking from distributor end! 

Hard to see from the photo. One brush is at 12 o'clock, one is at approximately 9 o'clock and the field is at approximately 3 o'clock.


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[Bob Culver]

The ideal main brush positon is where the voltage of adjacent comm bars is nearest to equal, where least sparking occurs. The position varies with direction of rotation and output. (one reason adapted VW dyns not ideal) The DEL does have provison for slight adjustment. I dunno who initially adjusted or how; customary to set at mid range if disturbed as most by now have been.
The original ammeter is very low resiatnce and ideal for the application. It can be calibrated in series with fancy one. Can do in comfort off the car using a battery charger and sundry bulbs.. Meters will not tolerate grossly excess current as when short circuited.

[JonE]

More general 1928 DEL (cast aluminium end housing) information:

the two brushes at 90 degrees are held by the same frame, so the micro adjust is just via about 1/2 inch or less in formal fore/aft "slots" in the frame. I was intending to re-centralise the position in the small allowed movement.

The top (thick) brush flex feeds directly to the D terminal.

My field coil setscrews (the big things on the outer casing) are ALL mashed from tightening hard or loosening off... suggesting they have been out since 1928? They are also in quite dark wrapping which looks newer than other things I've seen elsewhere. 

The springs which hold the brushes down are easily to set wrongly, so the 'pushing' bit slips off the edge of the brush holder. 
They are also impossible to put back on when dislodged, without removing the end plate.

 First signs of lack of good third brush regulation: loose brush fixing terminals; brushes practically at the level of the holder - so probably worn.            

[JonE]

Further diagnostics.... the solid wire from the 4th field coil to third brush was broken by the time it was disassembled.
Reading the corrected resistance for the coils from this wire to the external F terminal stud, on a decent meter, was only 2.0/2.1, so not a great deal more than the commonly low readings of the (2 coil) C35 models - something to consider if you are wanting to run an electronic regulator which needs 2.5/3.5.
The worksmanship inside the CAV unit is a cut above the Lucas offerings. Incredibly neat and purposeful. Bearings either end.

[JonE]

A year later and I've got the DEL out to continue putting it back together! The field coils and body are separate , just with the two wires from either end of the series of 4 coils. Can I assume that my 2.1 ohm reading (less another 0.4 for the instrument) confirms the internal resistance is long gone, or am I meant to be testing that some other way?

[Lowespeed]

Just a thought; when dismantling mine, I discovered a screw coming from the inside to hold the end on. From the pictures all the nuts appear to be missing but the end in place. I couldn't take the end off until I found the screw holding it inside from the brushes side.

[Howard Wright]

Just a thought; when dismantling mine, I discovered a screw coming from the inside to hold the end on. From the pictures all the nuts appear to be missing but the end in place. I couldn't take the end off until I found the screw holding it inside from the brushes side.

Thanks Andy

That answers my question on the ”dynamo identification” thread.  I wondered if you could remove the end piece to inspect or change the drive gear without removing the brushes.  Apparently not  .

Cheers

Howard

[JonE]

this one has 4 setscrews in the brush section under the brush 'ring', holding the outer housing on. It's neat as the D terminal stays with that centre section. In fact, for a two brush conversion, I'm thinking that the field connections can stay entirely with the fields and main body (isolated F connector emerges from it), as the second end can be earthed right in place somehow and the 2nd brush made to earth on the brush body. Will make disassembly very easy and far fewer trailing wires to catch on a spinning armature...

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Howard - I can't see why you couldn't, looking at this? If you have the early variant. The odd thing is that one of the four nuts is internal to the housing where you stick the distributor. Mine wasn't connected there - just the nut sitting in the hole.        

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