bottom of an ambulance

[scanthy]

What is the purpose of the chain on the bottom of an ambulance? If you listen carefully, when an ambulance drives by, there is a chain that drags on the street. What is the purpose of this chain and do all ambulances have them? When was this chain introduced to the ambulance.
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[TheEskimo]

Depending on what kind of area you live it, it could be snow chains in the wheel wells. Around my area they have the snow chains up in the fender and they have some sotra device that drops them down when needed to make installing them quicker.

[averagef250]

I've been told they're there to slap against the tires and break snow out of the tread. Not sure if that's true or not. Ambulances, busses and rescue stuff has them around here.

[robroy]

Good evening Scanthy,

That's a great question. Is it possible that the chain has something to do with providing a ground for the vehicle's electrical system, perhaps due to sensitive electronic equipment they normally have on ambulances?

Robroy

[fmartin_gila1]

Don't know about Ambulances, but back when driving Propane Truck, Had a chain bolted to the frame long enough to drag the ground in order to disperse static electricity.

Fred

[grncustomf100]

Thats funny. I've wonder this same thing for a long time. Snow chanis? Grounding purposes? I asked people about both of these. They had no clue but either one is possible.

One day, EMT's were walking in a resturant as I was walking out, I asked them about it. It is snow chains. Automatic at that. Hit a button inside and the go to work. I'm not exacly sure how they work. If the just spin in front of the tire or actully spin onto the tire.

I'm glad to see that such trivial things puzzle people as well.

[DuckRyder]

Don't know about Ambulances, but back when driving Propane Truck, Had a chain bolted to the frame long enough to drag the ground in order to disperse static electricity.

That is my understanding...

[70_F100]

Don't know about Ambulances, but back when driving Propane Truck, Had a chain bolted to the frame long enough to drag the ground in order to disperse static electricity.

Fred

Never saw one on a propane truck, even though I worked on many of them in my time.

It would seem that the sparks created by it dragging on pavement would create a bigger hazard than static electricity would present.

[Ranchero50]

Static, we have them on the electric carts here at work so we don't blow up the place while riding through explosive enviroments...

Jamie

[knightfire83]

And

Since they carry oxygen on board, I always believed in the static electricity explanation.

A bit of further research comes up with automatic traction chains: http://www.onspot.com/

But these are not what I have seen dragging off the back of ambulances and tanker trucks, so I stand by my belief.

[TexasTruck72]

This thread reminded me of an old Jerry Clower story, it goes like this:
Uncle Versie pulled un to the filling station with a chain draggin' the ground behind his model A truck. The station attendant said "Versie, what are you draggin' that chain fer?" Versie replied "I don't know, Standard Oil does and they make millions!".

[The Good Humor Man]

This thread reminded me of an old Jerry Clower story, it goes like this:
Uncle Versie pulled un to the filling station with a chain draggin' the ground behind his model A truck. The station attendant said "Versie, what are you draggin' that chain fer?" Versie replied "I don't know, Standard Oil does and they make millions!".

Am I missing something, I don't get it .

[fastEdsel]

The chains are for static discharge. Sometimes they are a black strap looking thing that is bolted to the rear bumper or axle of fuel trucks or anything that is hauling flammable liquids and when they touch the ground during normal driving the static is removed. These straps are less intrusive at night because they don't give off a bunch of sparks on the highway like the chains do when they impact the road and freak out the folks in the cars behind the fuel trucks. We have the same thing on our aircraft that are black wires that trail off the rear edge of the aerolerons. As the aircraft travel through high moisture or rain or volcanic dust, they build up static electricity and the static is removed by these "static discharge strips." When static is discharged through these they actually glow blue sparks on the ends. We call that "St. Elmo's Fire" and it also comes off the prop tips in the same kind of conditions or on take off during high moisture or borderline freezing conditions. The next time you fly an airline at night, get a window seat just behind the wing and if the conditions are right, you will see the strips glow blue.

[FreakysFords]

While no longer mandatory here, they were back in my day. One every ambulance, we had to check our Gnd Protection daily. As far as I know they all still have them here, just not mandatory any more.

Frank

[flyboy2610]

The forklifts at work have them. It's to remove static electricity. One of the forklifts lost it's chain once. The supervisor reached out to touch the forklift and wound up flat on his AstroTurf!
Couldn't have happened to a nicer guy!