# An interesting question



## tjkb230 (Mar 6, 2006)

*An interesting question (with a picture)*

What does the three lights on top of the truck cabs stand for??

It is very common on Japanese trucks, I not sure about European and American trucks.









Can you see the three lights on top of the cab?


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## nerdly_dood (Mar 23, 2007)

In the USA there are five amber lights along the top of the FRONT of trucks and five red lights along the BACK of trucks. I'm not sure why exactly they're there but I think it's just to indicate how tall it is. True, in this image they aren't precisely at the TOP of the truck, but the trailer is just as tall and has amber lights at the top front corners, as well as the five top rear lights.









In Europe there are two white lights at the top front corners of trucks for the same purpose, and I don't know if there are any along the back. Again they aren't precisely at the very top below, but you get the idea.


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## castermaild55 (Sep 8, 2005)

tjkb230 said:


> What does the three lights on top of the truck cabs stand for??
> 
> It is very common on Japanese trucks, I not sure about European and American trucks.
> 
> ...


these are speed signal lights by traffic law


（０ｋｍ）～●●●～（２０ｋｍ）～●●○～（４０ｋｍ）～○●○～（６０ｋｍ）～○○○
（●・・light off 、○・・light on）
it is abolished in 1999


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## FREKI (Sep 27, 2005)

Looked at a few trucks on my drive home from work today - didn't see any system so I don't think we have any such here in Denmark.. :dunno:


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## Energy2003 (Jun 13, 2007)

never seen that here in german-speaking country.

and those 2 lights at the top, may have normal security reasons (for the height oder something else)


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## Messi (Nov 18, 2007)

Ok, another good question is:

In South America buses have a kind of pipe connected to their front wheel, what is that for please?


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## Fizmo1337 (Mar 26, 2009)

I just love those American-style trucks  Fantastic designs. European trucks look quite boring and bland but probably more effective on our (smaller) roads


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## thun (Aug 8, 2007)

To make sure that the tires won't be stolen, I assume. 

The lights on European trucks (white on the front, red on the back) are simply to indicate that it is a large vehicle in the dark. It has nothing to do with the height, but with the width of the vehicle (in Germany, lorries need the lights on the corners of the vehicle when the vehicle is 2,10m ore more wide).


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## TopWatch (Jun 21, 2008)

I thought that the pipe where very common in all the world.

Some of them, are just to impress, because the function of these pipe in to indicate the air presure in the wheel, you can see it also in trucks.

Like in this photo









Sorry for my english... I hope I answer your question.
Saludos!!


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## Messi (Nov 18, 2007)

I've seen such pipes only in South America so far. So is it some kind of automatic tire pump?


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## StreetView (Jul 25, 2009)

^^

Yes, it is. If the tire has some minor air leak, it keeps pumping air into the tire, so you won't get your tires flat. I don't know if it's really worth it to install one of those devices, money-wise speaking. I think it's a good option only if:

Equipment costs + installation costs + added maintenance costs < Cost of having to stop due to flat tires (time not moving: delays, overtime pay for the drivers)


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## paulc74 (Aug 22, 2009)

Not sure about the rest of the world. But in Canada and probably the US. 

The 2 outer lights are called the markers. They well mark the edge of the truck.

The 3 inner lights are called the ID lights. They basically say this unit is over a certain width (8 feet I believe). So in essence they ID the unit. 

Trailers on the Front don't need the 3 ID lights because theoretically the tractor that is pulling it would have those lights. But trailers do need the 3 ID lights on the Back.


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