Why do chains hang under fire trucks

I didn't think they were for grounding, because they don't touch the ground, and you wouldn't need dozens of them. So basically, there's a servo that lowers a kind of cat'o'nine tails made of chain in front of the spinning tire for instant traction, right? Never actually seen it in use, though. That's it! I've been seeing them for years and I never figured it out. Thanks, Cheryl. I had always assumed they were related to grounding. I typically only see one hanging down - I assume that is just the way the chains are hanging that just one is usually visable.

Interesting history on the OnSpot site - original patent in in NYC, but took a Swedish gentleman to revive it in - "onspot" is Swedish for "instant"!

Son of a Been wondering what the heck those were for since I was like 10 or something but never thought to ask a Firefighter. That's an awesome invention right there. Automatic snow chains? I can't believe I've never heard of such a thing. That's sweet! Cheryl, Thanks to your husband all rescuers like him, they answer the call unfailingly and we are all better off for that.

I like his new ride but I miss the days when the local fire rigs were Detroit powered. I love that screamin DD sound you could hear from across town when they were hurrying. Originally Posted by eleven. Rich Wilkman. I wonder what purpose they serve out here where there is now snow. I know they've been on rigs since before that product patent date and the drivers all called them out as grounding aids. Maybe we're talking about different things that both dangle?

Learned something new today. Those are really cool. All times are GMT The time now is Join us now! Mark Forums Read. Car Talk Discussions relating directly to cars that do not fit any other forum. Topics may include those that might be found in a typical car magazine. Page 1 of 2. Thread Tools. Join Date: Jan Location: -- Posts: 3, Find More Posts by very hungry caterpillar. RichardNorman Fifth gear. Grounding chains?

Visit RichardNorman's homepage! If you have a car that sits low enough to the ground, you might be able to catch a glimpse of chains hanging from underneath the truck.

Why are they there? When that happens, a driver can flip a switch that will lower the chains so they hang in front of the back tires. The system makes the chains spin in front of the wheels.

When the tires rotate, they catch the chains, greatly improving traction on icy or slick roads. To find out more about the categories of personal information collected and the purposes for which such information will be used, please refer to our privacy policy.

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Page 1 of 3 1 2 3 Last Jump to page: Results 1 to 20 of Thread: OT: Chains hanging from truck back axle. Thread Tools Show Printable Version. OT: Chains hanging from truck back axle Being on the road for service work most days I have seen on occasion over the years seen chains hanging from the back axle of some larger trucks. Odd thing is that it seem to mostly been on fire engines or emergency vehicles.

At first I thought perhaps it was a place of convenience to hang the chain in case of need. But not too long ago I noticed it on a large delivery truck. I sped up beside of the truck and to get a better look and the chains seem to be hanging off the brake assemblies or rather the small round cannisters mounted on the back axle.

Does this have to do with what I now suspect is weight issues for the vehicle and brake system? I'm stumped, I've googled, ask around and found nothing for 6 months.

Does anyone here have a clue as to why the chains are there?