Dumb lights question

[VirginiaJim]

I can feel my brane starting to hurt...

[Conrad]

So what makes them "high" and "low" beams is just a matter of position?

It mostly depends on how much they've had to drink rather than position.

[VirginiaJim]

I knew this was going to happen.   Time for a refill...  Brane hurts...

[B.D.F.]

Well assuming this is a serious question....

The H4 lamps in a C-14 headlight have two filaments, one used for high beam and one used for low beam. Both headlights are used for both high and low beam.

The low beam has a shield under the filament so that the only light that can come out of the bulb goes up and is reflected down. The low beam produces a light beam that only shines down below the light and forward, hence the term 'low beam'. This prevents blinding other drivers in oncoming traffic.

The front of the lamp is painted black so there is no forward light coming out of the bulb no matter which filament is used.

When you switch to high beams, the low beam filament goes out and the high beam filament illuminates. There is no shield around that filament (high beam) so the light is scattered all around the reflector and then forward but there is no cut off line and the light shines both above as well as below the headlight itself.

It is possible for either or both filaments to fail in either or both lights; more than one filament will not usually fail at the same time but sometimes a rider is not aware that one filament has failed and so it is not noticed until the 'other' filament fails also and the motorcycle has no high or low beams, depending on which filaments have failed.

There is a slight overlap on the low / high beam switch when both filaments are on at the same time; if you find that spot and hold the switch there (or use the Flash To Pass switch) you will notice that there is a lot of light being produced- that is because both sets of filaments are on at the same time and the lights are using at least double the power they normally would. They also produce a lot of heat so it is not really desirable to ride with the lights used in that way.

Brian

So what makes them "high" and "low" beams is just a matter of position?

[maxtog]

The low beam has a shield under the filament so that the only light that can come out of the bulb goes up and is reflected down. The low beam produces a light beam that only shines down below the light and forward, hence the term 'low beam'. This prevents blinding other drivers in oncoming traffic.
[...]
When you switch to high beams, the low beam filament goes out and the high beam filament illuminates. There is no shield around that filament (high beam) so the light is scattered all around the reflector and then forward but there is no cut off line and the light shines both above as well as below the headlight itself.

While what you say is accurate, it does not take into account what is really causing the "high beam".  It is not the direction of the light (up or down or both) (which is what I used to think).  It is the exact angular position of the filament relative to the reflector.  The high and low beam filament are separated by about 1cm (just an estimate) on center.  The reflectors have dual focal points- one for the low beam filament position and one for the high.

This is why when using HID lights, you still have high and low beam patterns by simply moving the single "filament" (bright spot) HID bulb in/out to the two different focal points... With the HID conversion, the bottom half of the reflector is never used, only the top half is used.

Of course, this creates an interesting question that I cannot answer- WHY is it set up that way with the typical HID conversion (only using the top half), and WHAT are we losing by not utilizing the lower half of the reflector when in high beam mode?

[Conrad]

How's your brane now Jim?

[McJunkie]

The position of the switch.

So what makes them "high" and "low" beams is just a matter of position?

[Conrad]

The position of the switch.

ding ding ding. We have a winner!

[VirginiaJim]

My brane feels better now.  I knew it had something to do with the switch.

[B.D.F.]

The big difference between high beam and low beam on a stock H4 is that pan shaped shield under the low beam filament. It is very easy to test- simply put the lamp in the housing upside down; it will go although it will not seat fully. Look at the light pattern and you will find there is no cut- off and lots of light above where the cut- off line would be. The position of the filament (fore / aft) causes the beam to be broader or narrower, mostly top- to- bottom, which is why high beams when using an HID setup are on the thin side, again speaking of the beam's top- to- bottom shape.

The lower portion of the reflector is shaped to spread the beam differently than the upper portion; the lower portion spreads the beam out and more up/ down then the top portion. If the light source (filament or arc) is exposed to the lower reflector housing, you will generate a high beam shape no matter where (within reason) it is placed. So the reflectors on the C-14 generate a true high beam using the stock H4 lamps but only generate a quasi- low high (fixed original error) beam, although focused to a higher point (making it appear to be 'high') when using HIDs.

Brian

While what you say is accurate, it does not take into account what is really causing the "high beam".  It is not the direction of the light (up or down or both) (which is what I used to think).  It is the exact angular position of the filament relative to the reflector.  The high and low beam filament are separated by about 1cm (just an estimate) on center.  The reflectors have dual focal points- one for the low beam filament position and one for the high.

This is why when using HID lights, you still have high and low beam patterns by simply moving the single "filament" (bright spot) HID bulb in/out to the two different focal points... With the HID conversion, the bottom half of the reflector is never used, only the top half is used.

Of course, this creates an interesting question that I cannot answer- WHY is it set up that way with the typical HID conversion (only using the top half), and WHAT are we losing by not utilizing the lower half of the reflector when in high beam mode?

[c1obrien]

Maybe I'm a geek, but I love this conversation. I want to understand as much as I can about the bike. You guys are great.
chip

[VirginiaJim]

We have very knowledgeable members on this board that have loads of experience with this bike.  And it's a fun place to be if you have a sense of humor about you.

[B.D.F.]

It is a fun place to be even when the occasional poster does not have a sense of humor too- at least for the rest of us. The only thing better than a 'straight man' is a cranky person playing the unwitting 'straight man'.

 

Brian

<snip>

 And it's a fun place to be if you have a sense of humor about you.

[Son of Pappy]

We have very knowledgeable members on this board that have loads of experience with this bike. 

I sure wish one of them "Knowledgable" ones would show up

[B.D.F.]

Yeah, some of us get caught in the smaller details but that is what makes forums like this great- people who are not interested can just skip over these threads. I also find it to be an interesting subject with a lot of science and human effort put into it (vehicle lighting) to get us where we are today with was is really very good vehicle lighting.

Somewhat off topic: last night I was in Homely Despot and saw something that I found amazing- Ryobi has an HID "flashlight" (those two words just do not go together) for sale for something like $60 (not including the battery). Amazing- the entire light system including the ballast, the burner (bulb), a reflector along with a housing and switch all for $60. And it is the full power, 35 watt, 3,000 lumen of retina scortching HID too, not some puny 'little brother' types like the medical industry uses (and you cannot even believe where they shine those lights but that is a different subject....) Finally a flashlight that we do not have to polish the lens cover on to use- or probably even take the lens cover off.  Not many years ago those lights were thousands of dollars and only available as options on Mercedes Benz autos- now they are in the local hardware store as 'flashlights'. Back on topic (sorta'), I betcha' 4 of those things up front of a C-14 would provide a fantastic 'bang for the buck' lighting system if you could get by the cheap plastic housing and the flashy colors of the Ryobi product.

Brian

Maybe I'm a geek, but I love this conversation. I want to understand as much as I can about the bike. You guys are great.
chip

[B.D.F.]

And there we have it- some of 'dat 'dare humor coupled with an unwitting straight man....

<ROFLMFO three times>

Brian

I sure wish one of them "Knowledgable" ones would show up

[Son of Pappy]

And there we have it- some of 'dat 'dare humor coupled with an unwitting straight man....

<ROFLMFO three times>

Brian

Whatcha saying?  No sane, knowledgeable person would try what we tried and I aint ever been accused of being unwitting   I am straight tho

[gPink]

Somewhat off topic: last night I was in Homely Despot and saw something that I found amazing- Ryobi has an HID "flashlight" (those two words just do not go together) for sale for something like $60 (not including the battery). Amazing- the entire light system including the ballast, the burner (bulb), a reflector along with a housing and switch all for $60. And it is the full power, 35 watt, 3,000 lumen of retina scortching HID too, not some puny 'little brother' types like the medical industry uses (and you cannot even believe where they shine those lights but that is a different subject....) Finally a flashlight that we do not have to polish the lens cover on to use- or probably even take the lens cover off.  Not many years ago those lights were thousands of dollars and only available as options on Mercedes Benz autos- now they are in the local hardware store as 'flashlights'. Back on topic (sorta'), I betcha' 4 of those things up front of a C-14 would provide a fantastic 'bang for the buck' lighting system if you could get by the cheap plastic housing and the flashy colors of the Ryobi product.

Brian

Does it have a high and low beam?

[B.D.F.]

Yes and it is controlled by an electro-mechanical mechanism called 'wristus angulus', or something close to that, in Latin.

Brian

Does it have a high and low beam?

[gPink]

Yes and it is controlled by an electro-mechanical mechanism called 'wristus angulus', or something close to that, in Latin.

Brian

Google Translate makes that 'angle of the dangle'.