Chummy headlight options/questions

[RupertW]

Hello all,

I'm trying to get my head around headlight options for my late chummy project, which has the wing mounted forward headlights. I have a set of the slightly earlier CAV headlamps which I'm aware are incorrect but I'd like to use anyway.

What I'm struggling to get my head round is that the earlier headlamps only have provision for one bulb holder, rather than the later lamps with an extra sidelight holder in the reflector.

On my switch panel it has the options of off, side, and head lamp.

Would a late chummy originally have been able to dip the headlights? I have it in my head that the very early chummies had a dimming function.

My thinking is that I could put a dual filament bulb in each headlight and effectively use the sidelight setting as dipped beam. Is there any reason why I shouldn't take this approach?

Electrics definitely aren't my strong point so any thoughts much appreciated!

[Mike Costigan]

The early chummy headlamps had a single-filament bulb, and the switch-panel changed the circuit from series to parallel to give two levels of illumination.

[Howard Wright]

Hi Rupert

As Mike says early cars had the series parallel switch and a single filament bulb. I’m not sure of the date, but around 1928???? Cars had CAV or Lucas lights with double filament bulbs…then by the early 30s a separate side light.  

My RK (March 1930) has double filament bulbs, from memory the original incandescent was 5Watt and 35 Watt.

So a double contact bulb holder (Ba 15d) should allow side lights and head lights although both are not very bright.  It’s also advisable to run an earth, I use three core armoured cable.

Cheers

Howard

[David Cochrane]

Mike, that series/parallel arrangement was only on the very earliest cars with the first type of CAV 3-button switchpanel. The 2nd type used twin-filament bulbs (like stop/tail). Then the 2-lever Lucas switchpanel had separate sidelight bulbs in the reflectors. Unfortunately I don't know exact change-over dates - my late May 1925 car has the twin-filament arrangement.

[Tony Press]

My Lucas Spare Parts list 'Austin 7 HP 1927-28-29-30' shows:

Headlamps:

R515   1927-28

R47B 1929-30 

Complete with:
 
Reflector c/w Bulb Holder Interior -double pole R515 1927-28

Bulb R515 1927-28 D 618

Reflector c/w Bulb Holder Interior -single pole R47B 1929-30

Bulb (Main) R47B BAS1S 

Bulb (Pilot) R47B BAS8S

[RupertW]

Thanks all, I'd been leaning towards a ba15d fitting with a dual filament bulb. I think I've also seen LED equivalents that would fit so that's definitely a bonus.

From what I've seen ba15d holders don't typically have an earth wire - is it simply a case of soldering or otherwise attaching an earth wire to the holder? I'd like to earth as much as possible that avoid electrical gremlins (and flashbacks to the electrics on my Reliant Rialto)

[Steve kay]

   
   

   
Not exactly a direct contribution to this thread, but I recently came upon what has been thought to be an early dipping system. Not moving the headlight beam, but reducing the light emitted. Anyone with film or theatrehistory might well recognise something similar for a lighting desk, similar but very much bigger for mains. This is probably for 6 or 12 volt, badged Jos. Lucas Limited-Patented-Birmingham. Perhaps inaccurate identification will be challenged within half an hour. I think it would be highly unconvincing mounted on the dask of even a Chummy as dubious as mine, so would be very happy to pass it on to someone who has been looking for one for years. 

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