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Old 29th October 2010, 08:15   #1
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Default Chain at the rear of the Tata Marcopolo low floor buses

On a recent trip to Delhi i noticed that all the Tata Marcopolo low floor buses have a chain dangling at the rear.

Does anybody know what this is for ? Some sort of a gauge ? For the height / loading - similar to small aircraft ??

The Volvo Low floor buses I have seen in Bangalore do not have a similar chain.
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Old 29th October 2010, 09:02   #2
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If the chain in question is such that it occasionally makes contact with the road. It could be for discharging static electricity.
Which could explain them being present in Delhi and not in Bangalore. Delhi being drier and having a greater possibility of creating static electricity.

PS: This is what I understand by googling, chains at rear of bus.
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Old 29th October 2010, 09:50   #3
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In yester years I have noticed rear mud flaps made of steel wire meshing for many Ambassador taxis which were also used to touch the road. The explanation for which was similar to above one.
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Old 29th October 2010, 10:18   #4
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This used to be seen on petrol tankers as well few years back. Don't see them now, though!
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Old 29th October 2010, 10:28   #5
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As Bblost pointed out, the old lorries and buses used to have these chains to discharge the static electricity generated to roads as they come in contact with road once a while.
However I thought this was replaced at least a decade back and there is some system to pass these currents back to the battery (Donno details of how its done)

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GeorgeV
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Old 29th October 2010, 16:04   #6
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Quote:
Originally Posted by sfilinto View Post
On a recent trip to Delhi i noticed that all the Tata Marcopolo low floor buses have a chain dangling at the rear.

Does anybody know what this is for ? Some sort of a gauge ? For the height / loading - similar to small aircraft ??

The Volvo Low floor buses I have seen in Bangalore do not have a similar chain.
As much as my knowledge goes, the chain has nothing to do with static electricity. If you see carafully, the chain would have also had a metal tagging. As required by the law, each CNG cylinder needs to have its tagging and these are Cylinder tag chains and when it comes loose, you may see it hanging.
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Old 29th October 2010, 16:35   #7
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I believe it is used for current discharge from lightening strikes, like what we have in our apartment tops etc. Imagine the situation wherein the trucks travel alone in vast lands and no conducter for electric charge from sky.

Just my thoughts though
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Old 29th October 2010, 16:42   #8
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Quote:
Originally Posted by lambuhere1 View Post
I believe it is used for current discharge from lightening strikes, like what we have in our apartment tops etc. Imagine the situation wherein the trucks travel alone in vast lands and no conducter for electric charge from sky.

Just my thoughts though
As per basic physics, the electric field inside the vehicle is zero. So if a lightning strikes, the electricity will pass from outside the body and since it is very high voltage, it will go to ground using the path of least resistance that is polarising the air and causing a spark. So a chain is not required.

Top Gear video to partially explain what I'm talking about
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Old 29th October 2010, 17:20   #9
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Quote:
Originally Posted by MileCruncher View Post
As per basic physics, the electric field inside the vehicle is zero. So if a lightning strikes, the electricity will pass from outside the body and since it is very high voltage, it will go to ground using the path of least resistance that is polarising the air and causing a spark. So a chain is not required.

Top Gear video to partially explain what I'm talking about
May be not to discharge the lightining strike but for other static charge like they put for oil tankers.
Static charge is not big enough to polarize the air but can create sparks
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Old 29th October 2010, 17:40   #10
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The buses are CNG and if there is any kind of leak, static electricity can lead to a major fire. Due to this reason, many vehicles have chains dangling down to ground the charge before sufficient buildup occurs.
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Old 29th October 2010, 17:51   #11
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Tanveer is right, you would see similar chains on explosive trucks as well.
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