Headlight bulb orientation

My guess is that the shrouded filament is the dipped beam, and that the shroud would be downwards. That would only allow the light from the filament to shine on the upper part of the reflector, which should then reflect it forwards and downwards.

A double filament bulb usually has a holder which only allows the bulb to be inserted one way round, so if you are looking to do a halogen replacement for a conventional twin-filament bulb, it should be a straight swap and end up in the correct orientation.

Jim

Your interpretation of the way the dipped beam works matches my thinking, basically that the upper part of the reflector shines down, and vice versa. This bulb and holder have non-directional pins, so can be inserted in either orientation. The bulb base is held in place by a clamp, so there is zero guide as to how to insert it in place! The orientation of the bulbs in the holders as received was clearly random, hence my query.

Thanks.

I've never seen a headlamp bulb where it is possible to fit it upside down.

They generally have a flange which only fits the housing in one way.

The older 'standard' round headlights had three fixing lugs spaced such that they would only fit one way too. But usually obvious by some lettering etc on the glass too.

The cover over the filament on dip etc acts like a french flag rather than reflector.

Well, now you have!

Not these,as you can see from the pic.

I found this:

"Offset Shielded Dipped Beam.

This double filament bulb (Fig. 29.10) is most popular. The main filament of this bulb is placed at the focal point of the reflector and the dipped fila­ment brought forward of the focal point. A metal cup or shield is positioned just below this dipped filament. Similar to the other two types of bulb, the main filament provides a reflected long concentrated beam parallel to the principal axis. The dipped filament produces an out-of-focus converging beam, the upper half of which points in a downward direction but the light rays from the lower half is prevent from striking the reflector by the shield, due to which none of these rays can cause dazzle by being reflected upwards."

This confirms that the shield goes below the dipped filament, as the light is indeed reflected downwards from the upper part of the reflector. The referenced figure confirms this.

Coupled with the fact that there is no room to adjust the position of the bulb horizontally, I am thinking of abandoning these if I cannot quickly make them work. Luckily, they didn't cost me anything. But at least I now know to install them to try them.

The ref. is to:

It won't load here.

Difficult to be certain without seeing it, as there are so many varieties. If it has a sharp cutoff, most likely achieved by a flag.

It took two goes for me. After a long pause I got a few dropbox controls but no picture. From there I went for "reload page" and the picture came through.

I think it must be a dropbox problem. Other websites don't show any unusual delay.

Jim

It's the first time I have used the revised Dropbox. When I checked the picture this morning, it too took a long time to load, but did eventually. I never used to have this problem, but they 'improved' the site, and we all know what happens then.