I'd think a dual filaments bulb is for redundancy safety. If one filament
was broken, there's the other one - no running or no blinker, but at least
there's one functioning while waiting for the bulb to be changed. If one
ligament and it's gone, there'd be nothing.

On Sat, Jan 21, 2023 at 12:02 PM Raimund Feussner <ray@v6bus.de> wrote:

> 1. In Europe we don´t have sidemarkers. In the front we have
> stand/position lights as 5W inside the headlight housing. White.
> The turn signals are "turn only".
> 2. All bulbs basically have their own circuitry, no bulb is shared
> between functions (except common ground)
> 3. The lights from .1) move into the turn signals in USA, to allow front
> sidemarker function, but still have the same stand-alone circuitry. The
> US blinker lenses are different, to allow this, the bulb socket (2 vs
> 3-pin) as well.
>
> Opposite example:
> I, as a german, never understood the way of how the rear brake signal
> turned on and off during blinking. The principle of using one bulb for
> two circuits has to show its flaws sooner or later.
> Although Germans love the US style lighting...
>
> Raimund
>
>
>
> Am 21.01.2023 um 20:15 schrieb OlRivrRat:
> > On 21 Jan , 2023, at 11:18 AM, Eric Caron<ericcaron96@comcast.net>
> wrote:
> >> Also, Do they work in both the front and rear signal areas?
> >                  Eric
> >
> >          These do not work in the Rear since all the bulbs in the Rear
> are Single Contact
> >
> > & these are Dual Contact so they can be both Running & Blinker in 1 Bulb
> ~ Not sure
> >
> > why the Germans thought they needed to Duals as they could have simply
> turned the
> >
> > Running Lights Off & On to do the Blinkers ~
>