What are the little plastic “bumps” on the headlights of some cars? These are protrusions of the clear plastic shield and they don’t appear to correspond to screw holes or anything else. All that they do on my F150 is snag the sponge when I’m washing my truck.
I noticed this morning on my way into work that they only seem to be on the front headlights, never on the rear, and some models have them while others don’t. My Ford F150 has them and a shiny new Mercedes sports car did as well, whereas a late-model Chevy truck didn’t have them. The Mercedes also had those little “windshield wipers” on the headlights so the plastic spike doesn’t interfere with them.
Random thoughts:
Artifact of the molding process at the plastic factory, like on parts of a plastic model kit.
Somehow adds strength to the plastic shield.
Prevents a big stack of the parts from sticking together when they are shipped to the assembler.
Helps prevent rain or snow or ice from sticking/forming by affecting windflow over the plastic lens.
None of these make much sense to me but it’s all I could think of right now.
Perhaps you have never heard of the Department of Transportation aka dot, which sort of wants headlights to aim a certain way, those bumps make it cheap and easy to aim cheap headlights. I’m not sure expensive sports cars would have them, as they may opt for more precise aiming methods.
Like I said, the expensive Mercedes sportscar next to me on the freeway this morning had them. Some cars have them, some don’t. Didn’t seem to hinge on the type or relative cost of the car. When I aligned the lights on my old Toyota Celica it used a couple of adjusting screws, I assumed that’s how all cars handled it.
One thing that the alignment idea has going for it is that I’ve never seen these bumps on anything but the front headlights.
The bumps themselves don’t align the headlights. They are the contact points for the tool that is used to determine the correct aim points. Basically the tool I’ve seen in the past is a spirit level with a plate that rests against the bumps on the lens. The lamp adjusting screws, under the hood, are adjusted until the level reads correctly. When US cars all used sealed beam lamps there were only two sizes, so only one tool was used for each size lamp. Now with all the different aerodynamic shapes it’s not that simple.
Gary T nailed it as usual.
The optical aimer had three rods that had a concave end on them that protruded forward of the aminer. In the center was a large suction cup, and a lever to move the suction cup forward and back. You place the rods on the tits then you put the cup on the lens, and pulled the lever back till it locked the tool to the lens.
As Gary T mentioned, there was a level in the unit for up and down of each bulb, in addition, there was a mirror arrangement that you looked through to see if the bulbs were aligned properly in the horizontal axis. Here is one such unit. As Gary mentioned, many cars now no longer have those tits, and must use an optical aimer.
We Brits have to attach headlight beam deflectors to our cars when we take them over to mainland Europe (what with those foreigners persisting in driving on the wrong side of the road). They stick onto the headlight plastic, and the instructions that come with them have a bucketload of diagrams showing where to stick them on different models of car. The diagrams usually refer to the headlight nipple, which lends weight to the “alignment” answers above.
Interesting product Colophon. Your British headlights used to have, and probably still do have, a “tail” of light that aimed more light higher on the left side, which would be your road shoulder, while the folks on the continent would have their “tail” on the right side.
Years back, when the USA was limited to sealed beam units, folks would buy european lamp units that had the seperate bulbs, usually halogens. People who were into off road rallying would obtain a british unit for the left side of the car, and a continental unit for the right side. That way both shoulders would be fully illuminated. Of course any on coming drivers would suffer, but in an off road rally situation it wasn’t an issue.