Tillage and Welding experts

Seems the spring planting is moving along, but I've got a problem with my farmer friends John Deere 637 disc, bought new 2-3 years ago.

Right side front gang, fold down/up gang, attached to the tool bar (square tube)is a 1/2" x 3" x 3" x 12" mild steel angle, stitch welded to the tube and is what connects to the larger tube, that is connected to the cylinders which raise and lower the outer gang/wing. Problem is that darned angle ripped apart, I welded to the tube and the ripped areas, 7018 sure is strong, but the angle ripped again, I caught it prior to tearing off again, appears to be A60 mild steel.

I am not familiar with adjusting a large set of discs like this, though we seem to have it leveled up, depth and that center valley, outer windrow of dirt adjusted via the large crank in the center, he's got the book yet I've never had a chance to read it. I am thinking one of 2 things, either he keeps hitting something hard or something is out of adjustment, anyone have any ideas ?

Now, I burned off the 1/2" angle, barely nicked the tube with the torch 1-2 places, was a pain to get in there too, so I'll fillet those small spots with 7018, grind etc, other than those nicks you could see what you were cutting, so it was clean, I've often wondered if when you do that + heat, does the steel, (think the tube is A60 mild steel too) become compromised or embrittled ? This is the first time, but say that angle tears again, cut off weld, will this weaken that tube to any serious degree.

I called in to order the angle I need fabricated and will weld it in place, but I hope the darned thing does not tear out, I will weld just as the factory did, stitch like the others, and use mild steel, but had wondered if I beefed up that one, it would place the stress elsewhere, if so, the repair won't be easy, might be into more than a 12" piece of angle. Appreciate your input, he's got another 100 acres to do, most is farthest from the shop, so breakdowns will be a pain if they happen.

Billy,

Just a few thoughts here as I am not familiar with that disc.

When the disc folds does it hit some kind of stop before the cylinder has run out of travel? The cylinder has huge forces and can be causing the ripped metal. Possibly you need to readjust the position of the cylinder so the cylinder is at the end of its travel just prior to the folding section hitting its stop. Or maybe you need a collar fitting on the cylinder ram to limit the cylinder stroke. Did the disc come with these lifting cylinders, or are they just a common size like a 3" x 8"? My thought here is that you can limit the force applied by chosing a smaller diameter cylinder...maybe a 2.5" x 8". On our different brand disc, the 2.5" diameter cylinder gives plenty of lift force.

Were the cylinders sized for the old standard 2500 psi hydraulic systems common to many tractor brands? And is he using a newer tractor that puts out 3500 or 4000 psi to the remotes? The higher pressures will rip things apart if no pressure limiting (relief) valve is used on the implement's hydraulics.

As to the welding, if you are using a mild steel like a 60 series, then it would be best to use a 60 series welding rod. Deep penetration can be had with the common 6011, and it can be run with AC or DC. The 7018 is a low hydrogen rod which is designed for high carbon steel. It can be run on AC or DC, but my experience suggests that it gives a more brittle weld or brittleness next to the weld. I think this can be reduced by preheating the base metal (w/torch) prior to welding.

My experience with my newer JD (and other brands as well) equipment is that they are using high carbon (high strength) steel in high impact stress places where it fails due to its more brittle nature. And welding repairs just make it even more brittle and ready to break again. So I have added "patch plates" to the repaired original metal that are known to be common hot rolled steel. This seems to withstand impact better. When welding such patch plates, do not fully weld the perimeter of the plate as it will probably cause the base metal to tear out completely. Thus the design with the "stitch welded" pieces. And make the patch plate cover a bigger area so you spread out the impact forces.

Have you had any experience in making knife blades or swords (or even plow shears)? Basically you want the high carbon steel only on the cutting edge, but the body of the blade needs to be tough but flexible (softer steel) or the blade will have a very short life before it is snapped off. I wish the current stock of Ag engineers who are specing out the materials for new equipment had some of this kind of experience. They should be required to serve a 6 month "apprenticeship" with a good blacksmith. The final product might be a whole lot better.

Good luck with solving this problem.

Paul in MN

P.S. I am neither a welding expert nor a tillage expert, but do have some experience in both areas, and am a member of a blacksmithing group. Maybe some real expert will respond as well.

Paul after reading what you posted, I am going to take a look at the hydraulics, but it seems the cylinder end is slot shaped meaning it's got plenty of free end play, basically there are 2 on each side to raise up the outer gangs for transport. You made a good point with that, maybe I missed something there too. I've raised and lowered this 637, folded it up, and while watching that cylinder near the repair area, seems like it's got free play.

I also think I miss classified the steel, it's mild, but A36 I think, I spoke to my friend who owns a good size steel fab shop, he is fabricating a new 1/2" angle for me, seems everyone knows each other on this deal here, he actually borrowed my friends late model 7420 JD for his wedding arrival, they polished it and waxed it up for an opening parade, he says I can't charge this guy for the steel, so I got an extra piece in case we have another failure. I thought that was too funny, the other day the guy who charged $3000 to repair his (farmer) '90 3/4 chevy, trans and other work, charged him $10 to adjust/fix the trans linkage, come back work, some people are just bad like that, good to see someone remembering a favor like this.

I'm headed back to his shop to get the steel, then to the farm to complete this repair, I will take some photos and make an additional post, so all can see the problem area, though I took a photo with my phone, of the 2nd time it failed, both fractured, don't have the cable to upload.

Well I think tear is a better way to put it, I don't think it was embrittled, but possible near the welds I suppose, then kept tearing further, would not have been but a few more acres and that sucker would have had to been chained up to get it home. I think if it was brittle, with all the rocks, and rough terrain, and soils, it would have come right apart, but I ain't no expert either, hate seeing this expensive rig getting tore up, had to be $20-$30k new.

One of the fractures/tears, I welded both sides with 7018, heat turned up, almost flat weld profile, no sign of embrittlement or failure, steel angle failed in new areas 2nd time.

I think some photos are in order, hard to describe without, but I just can't seem to figure what in heck is putting so much stress on that side, someone here might see something I am missing, will be back later with a 2nd post on this, time to go get er done !

Billy, does this disk have the hydraulically adjustable down pressure for the wings? If so, you need to lock your hydraulic lever down to activate it. If you do not use this feature you MUST put your hydraulic lever in float. If you do not you will break something because the wings will not give. Mike

Curiosity is getting the best of me: was there some sort of warranty on the disk when it was new?
I wonder if part of your welding problem is the tubing and angle are a higher carbon material than you think. You might try using some preheat and then welding. The other thing I might suggest is using a welding rod with a higher tensile strength such as 8018 or up to maybe 11018, which is what I use all the time on T1 steel, along with a bit of preheat.

Sam, the good news with this is that the welds I did to the shelf angle on the tube, held with no problem, but the angle/steel tore in another place, no sign of it coming off the tube at all, so I think the process, plain ole 7018/DC positive is ok and this is mild steel, well I am pretty sure, not so sure what JD uses. It was not easy to cut off, could not get it in one piece, that sucker was on there, and the replacement is now about the same, I put some fat welds up top, steel will fail first I think.

I too am curious about warranty and getting someone from the dealership out here, if it fails again, he's going to have to do that. The only thing I can come up with right now is when I put put it back together, I lifted the wing gang up with his loader, got 2 bolts lined up & in, but the inside one I had to set it down and lower it down from transport, slightly off, but nowhere near close when up in the air, this could be it, maybe something, like the main tube for both wings, is not aligned, raising & lowering, causing stress, something just is not right and I suspect I'll be at this again, wrapped er up around 9:30 last night, greased er up and parked er by the fuel tanks, she's ready, but this still has me concerned.

I don't believe it has that feature, with down pressure, just raises and lowers for transport, and the outer gangs/wings raise. It's manually adjustable for level, depth and the center valley/outer windrow of soil, from what I have seen helping him adjust it. My friend Leonard is an overly simple ole farmer, sometimes he misses things, I see this and like to help when I do, but I have to say he sure aint no dummy by any means and a real pleasure to work with, heck he made it all these years so far, just human like the rest of us, sometimes things stare all of us in the face and we still don't get it, I just don't want to see this thing come apart or become damaged, darned expensive rig he's got there, he's pulling it with JD 4440 w/duals, all matched and new tires. I will double check on this just the same, need to get my hands on that book again.