2188 breaking comcave bolts

Darald

Member
We are harvesting lentils, lots of straw, poor yield due to disease. 25 foot flex 3 mph max, and every morning the bolts in the middle concave are broken. I have tried grade 5's and 8's, both break. At times a fair bit of material is going in and the governor responds. I don't know when they break as I can't really tell a difference in the sample and really nothing going over. What bolts do I need?
 
Don't think the bolts are your problem. You've got something else going on. Besides, if you got bolts strong enough to hold, then you'll likely just break the end plate off the concave.

First I'll ask the most obvious question. Do you have all four bolts in the concave? I shouldn't have to ask that question but it's funny how many people don't realize they need all four bolts in or don't know they are supposed to.

Now this is important.
Do you tighten all four bolts equally? Meaning you need to snug all four of them just a bit before you tighten them so everything makes metal to metal contact on the end plate top to bottom and side to side.

If you tighten the front two bolts first while the weight of the concave is hanging down on the bolts, you'll end up with an air gap between the plates on the top bolts, which isn't holding anything and they will come loose leaving only the bottom bolts to handle all the stress. Same thing will happen if you tighten the top bolts first without snugging the side bolts to get rid of gap.

I always use an aligning bar or big punch in the middle hole provided and just wiggle the concave up and down and side to side as I snug all four bolts at the same time equally with hand wrenches until I know it's seated itself snugly into the cradle before I do any serious tightening with an impact.

Do you have the adjoining bolts installed? There should be bolts that connect the first concave to the second, and the second concave to the third. The holes are on the under side of the concaves and are hard to reach to install them but you need them in. It helps spread the stress across all three concaves together when a wad goes through rather than each one handling it individually.

Are the stalks still green and damp?
Do they need to dry down more regardless the moisture of the seed? It's quite early yet but in my area, we sometimes had to wait for a killing freeze before the bean stalks would give up their moisture.

Do you run a specialty rotor? This is a must for soybeans. If you don't have one then get one from a junkyard or buy a new one if you have to. It will literally save you from tearing up the insides of your combine in soybeans or any green stemed crop and increase capacity and decrease fuel consumption to boot. Well worth the investment.

Do you have the vanes above the rotor cage adjusted properly for the crop conditions?

Do you have the concaves adjusted to the correct clearance for green stems? To tight the rotor will plug. To loose the crop will twist and ball up into a wad on the way through.

I forgot to mention the other end of your concaves. The "hook" end of your concave sits on a pipe with another pipe bolted on top of them to hold them down. Make sure the pipe isn't bent or damaged, letting the concave flex up and down and breaking your bolts. Back in the days before we had specialty rotors, green steamed beans would thump so hard going through we used to bend or break that pipe right out of the machine. Took to upgrading the pipe with a thick walled pipe from the local machine shop. But again, every time we beefed up a part of the machine, it just broke somewhere else.

Another item is the eye bolts on that hold down pipe. We used to stretch and spread the eyes until we took to welding the loop. Now I think they come welded from the factory.

The specialty rotor solved all those issues by being able to thresh the material evenly as it went through the machine rather than ball it up and make things worse like the standard rotor did.

Not related to this topic maybe but the change over from the elephant ear impeller blades to the screw at the front of the rotor did wonders also for better feeding, better threshing, better wear and better fuel efficiency. The IH boys need to thank the New Holland boys for showing them how it's done.

Anyway, just a few things for you to chew on. Like I said at the beginning, no reason for you to be breaking bolts. There must be something else. One more thought that seems trivial but you never know. Are you using the correct size bolts? And are they whiz bolts and whiz nuts or are you using standard bolts and lock washers? Could make all the difference. Let us know what you find if anything. Good luck.
 
Straw boss explained it so thoroughly I can't add anything to it. We ran three 2188's, then twelve 2388's in tough green 120 bushel irrigated wheat that sucked every pony out of the engines full time and we never broke concave bolts. We had trouble with the H bracket the rotor gearbox bolts to breaking on the 2388's from the constant high engine torque but the conclaves stood it OK. An unbelievable amount of straw was coming out of the back of the machines.
 
Thanks to both of you, my problem got solved by installing 5 bolts and tightening them according to Straw Boss's instructions. I picked up bolts at the dealership, they gave me three, 5/16 x 1 1/2 grade 8, instead I used 5 3/8 x 1 1/2 grade 5 and the final tightening was with a 1/2"drive swing handle and all I could muster up for the pull. I also like the idea of a different rotor as flax is one of my crops and is usually hard threshing. Thanks again guys.
 

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