Gleaner Field fires

Pengs5

Guest
#1
Usually our concern in aussie land is fire at harvest _summer time with 100F (40c )plus temps. This year Bogged and wet grain . Yeah drag a chain as static can start especially in fuzzy dust of beans etc. Draper fronts with them rubber belts rubbing around steel tube rollers are like them school science electricity machines (cant remember the name of it ) but the same concept. We keep our own fire truck on field and usually first thing to paddock. pengs5
 

NDDan

Guest
#2
Yea I have to think it is a good idea if in dry flamable conditions. See plenty machines draging chains. I heard of a condition in flax one time that crop would float right over chaffer due to static. It was described to me that they had to drag a heavy chain and even a weight on end of chain to make good connection to ground. Seems like no question about it. With all the friction within a combine there is bound to be static and if draging a chain helps prevent a fire then I would sure go for it.
 

Ed_Boysun

Guest
#3
I'm curious as to why you think a drag chain is necessaryIJ The machine sits on four tires that are heavily loaded and making contact with the earth. The carbon black that is added to the rubber compound to enhance wear and as a side effect; responsible for making the tires black and not red or white, makes them a decent conducter of electricity.
 

Pengs5

Guest
#4
Yeah i know but the tyres are also insulating between earth and steel of machine . Our newer car zaps me all the time when i get out of it . pengs5
 

Ed_Boysun

Guest
#5
Well I've posted this before on different forums so I guess I might as well copy and paste it here: Combines, fires and drag chains . . . I too heard the hint about dragging a chain from the frame of a combine to keep the machine from building a static charge. At the time, it was supposed to help keep the glass windows from attracting dust and make them easier to keep clean. I later heard that it was supposed to help prevent fires. I tried dragging a worn out chunk of stainless steel roller chain. Aside from the feel good factor, I really couldn't say that it did any good. After all, when is the last time anyone stepped off a combine and got a shock as he had his hand on the step rail and touched the groundIJ I've been around combines for some years, and typically work in hot, lo-humidity conditions; much like the guys in Oz do. So, a few years ago, I did an experiment to see if the static buildup is mostly myth and whether the conductivity of the tires does what I thought it would do. Here's what I did: Tires vs. drag chain. I had time to check out just how conductive combine tires are, whether they insulate, and whether the drag chain helps, hinders, or is mostly psychological. Here is what I found: Front tires are bias ply 30.5 X 32 and the rear tires are 16.9 X 26. I ran the front tire onto a sheet of bright, untarnished copper and one lead of a Fluke 77 VOM to the copper sheet and the other to one of the lug bolts of the rim. In order to confirm that readings didn't reflect capacitively charging the machine and affecting the reading, I took readings with leads first connected one way and then the other. There was no noticeable difference in the resistance readings that was dependent on the polarity of the test probes. The readings also remained constant, indicating no capacitive charge or discharge. Front tire lug bolt to sheet reading was 97 K. When I moved the combine to place the rear tire on the copper sheet, I got a value of 350 K for the back tire. That gives us two paths with a resistance of 97K and two with a resistance of 350K. If I remember my basic Ohms law, to find the value of resistors in parallel you sum the reciprocal of all the values and then find the reciprocal of that number to determine total resistance. I came up with 37.975 K from combine frame to ground. If you consider that walking across a carpet in a dry room will charge your body to about 35,000 volts, then the path to ground offered by the tires would let nearly 1 amp of current pass at that voltage level. Enough static buildup to start a fireIJ I don't think so. I did hear from one guy who tried the drag chain method. He put one on his combine years ago to keep dust off the windows. That did not work for him either but it did do a couple of things. It beat all the paint off the combine frame in the area where it was mounted, and once when crossing a barb wire gate with a splice in one wire, it snagged that splice in a chain link and balled up the gate under the combine. As far as your car zapping you: It's the same reason that I get zapped when I come into my office in my machine shop that has very low RH in the winter. I stand on the carpet and remove my coat. Nothing happens until I touch something that's grounded like the case of a computer or the screw that holds the cover plate on the wall switch. The path to ground discharges what build-up I accumulated from removing my coat. likewise, you are charging yourself when you slide across the seat of your car and the soles of your shoes insulate you from ground with what static you've built. When you touch the car, it is near earth potential and the charge you just built by sliding across the seat, drains from you to the earth through the car via the conductive tires. If you were indeed draining a charge from the car, you'd feel it as the static overcame the resistance in the soles of your shoes. Believe me, that is very uncomfortable.
 

peteguy

Guest
#6
We always run a drag chain. We have dusty windows as well, but we have never had a field or combine fire either. Coincidence or not, it is not a bother to have, and it gives us peace of mind, so we will probably contine to do it. On a side note, the poly tin theory may hold a little bit of truth, I work for a guy with poly tin and it does feel static-y at times. As far as chain, I like using the light 3_16 chain, as it looks nice, and should conduct fairly well, plus, if it snags, light chain like that should break off as compared to heavy roller chain. I always have it bolted to the right rear corner of the frame. F,M,and l series have OEM holes already, N series probably does as well, and I dont know on R series. I then find a piece long enough so that it wont get caught by a tire at full lock, but is long enough to flip over the return elevator for road transport.
 

Pengs5

Guest
#7
Mythbuster Ed. Yes i know i know i too am a bit scepitical. My glass is always dirty and machine dusty. Will take chain off and see if the dust is any different I was just thinking rubber tires were a good insulater. pengs5
 

ROCK

Guest
#8
Just a thought with the responses I saw. If the ground is so dry, don't I need moisture to conduct static or electricity to ground. How can I do that if it is so dry in fields like this yearIJ Just wondering
 

NDDan

Guest
#9
Come to think of it if you figure a spark from corn head hitting rock started your fire I wouldn't want a chain rubbing on rocks all day.
 

Rolf

Guest
#10
Yes we draged a light chain under combine! If I ever hit and S.W.E.R (over head power line!) It had some where to earth to! Working With Marvin Gorden 20 years ago(This site Host) My Aussie Cutter mate, did hit a power line with A JD 6620 SH machine via the FM CB radio! Pin holes in every tire and no electrics, (not that the 6620 needed any to run!) But a pain in the butt! We put a chain On both combines after that, and 6620 hit power line again later in the season (diffrent driver!) Not me! and apart from blowing the alternator no other damage! Oh, needed new light drag chain! As links were welded together! :)
 
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