Discussion:
Headlight bulb orientation
(too old to reply)
Davey
2015-11-13 00:09:23 UTC
Permalink
1 have acquired a pair of halogen (I believe) headlights 'kits', the
bulbs are as seen here:

Loading Image...

Am I correct in thinking that this orientation is correct, with the cap
for the front-most filament above it? This is presumably for the dipped
beam, but I would have thought that this would reflect the output
upwards on leaving the lamp unit. There are no markings on the bulbs at
all.

Any help welcome.
--
Davey.
Indy Jess John
2015-11-13 00:27:16 UTC
Permalink
Post by Davey
1 have acquired a pair of halogen (I believe) headlights 'kits', the
https://www.dropbox.com/s/imvpaq82vifpnhn/small_0160.JPG?dl=0
Am I correct in thinking that this orientation is correct, with the cap
for the front-most filament above it? This is presumably for the dipped
beam, but I would have thought that this would reflect the output
upwards on leaving the lamp unit. There are no markings on the bulbs at
all.
Any help welcome.
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
Davey
2015-11-13 08:53:33 UTC
Permalink
On Fri, 13 Nov 2015 00:27:16 +0000
Post by Indy Jess John
Post by Davey
1 have acquired a pair of halogen (I believe) headlights 'kits', the
https://www.dropbox.com/s/imvpaq82vifpnhn/small_0160.JPG?dl=0
Am I correct in thinking that this orientation is correct, with the
cap for the front-most filament above it? This is presumably for
the dipped beam, but I would have thought that this would reflect
the output upwards on leaving the lamp unit. There are no markings
on the bulbs at all.
Any help welcome.
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.
--
Davey.
Dave Plowman (News)
2015-11-13 09:33:07 UTC
Permalink
Post by Davey
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.
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.
--
*If only you'd use your powers for good instead of evil.

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.
Davey
2015-11-13 09:45:42 UTC
Permalink
On Fri, 13 Nov 2015 09:33:07 +0000 (GMT)
Post by Dave Plowman (News)
Post by Davey
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.
I've never seen a headlamp bulb where it is possible to fit it upside down.
Well, now you have!
Post by Dave Plowman (News)
They generally have a flange which only fits the housing in one way.
Not these,as you can see from the pic.
Post by Dave Plowman (News)
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.
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:
http://what-when-how.com/automobile/headlight-automobile/
--
Davey.
Dave Plowman (News)
2015-11-13 13:29:31 UTC
Permalink
Post by Davey
Post by Dave Plowman (News)
I've never seen a headlamp bulb where it is possible to fit it upside down.
Well, now you have!
Post by Dave Plowman (News)
They generally have a flange which only fits the housing in one way.
Not these,as you can see from the pic.
It won't load here.
Post by Davey
Post by Dave Plowman (News)
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.
"Offset Shielded Dipped Beam.
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.
--
*There are two sides to every divorce: Yours and shit head's*

Dave Plowman ***@davenoise.co.uk London SW
To e-mail, change noise into sound.
Indy Jess John
2015-11-13 13:45:00 UTC
Permalink
Post by Dave Plowman (News)
Post by Davey
Post by Dave Plowman (News)
I've never seen a headlamp bulb where it is possible to fit it upside down.
Well, now you have!
Post by Dave Plowman (News)
They generally have a flange which only fits the housing in one way.
Not these,as you can see from the pic.
It won't load here.
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
Davey
2015-11-13 14:25:12 UTC
Permalink
On Fri, 13 Nov 2015 13:45:00 +0000
Post by Indy Jess John
Post by Dave Plowman (News)
Post by Davey
Post by Dave Plowman (News)
I've never seen a headlamp bulb where it is possible to fit it upside down.
Well, now you have!
Post by Dave Plowman (News)
They generally have a flange which only fits the housing in one way.
Not these,as you can see from the pic.
It won't load here.
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.
--
Davey.
Loading...