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Discussion Starter · #1 · (Edited)
Hi everyone, I hope all your crops are excellent.

I purchased an 1982 27foot header front off an N6 to fit to my "new" 1995 R72 7283 with a non variable speed header drive. When I used it to harvest wheat the header was vibrating badly at 2200 rpm or operating speed. When I reduced the engine speed to 1750 rpm the vibration stopped. I was told the wobble box was reconditioned not that long ago and it seems to be fine from my limited knowledge. The operators manual states the combine feeder counter shaft or header drive runs at 624 rpm. I checked this with a cheap digital shaft speed tester at 644 rpm at 2200 rpm. Both the header pullys that drive the wobble box are the same size, so the wobble box is doing 644 rpm or 624 there abouts. This is what the manual says for a 1995 model header that would have come with the R72. This front of course did not.

My question after all that,sorry is; Did the N6 combine have the same speed drive and wobble box speed as the R72. The old 27 foot header came off a variable speed header drive N6. They ran it at the slow speed. I don't know what that speed is. On mine at 1750 rpm where it isn't vibrating the wobble box is doing 513 rpm. On old 7720 headers of the same era as this gleaner header I think that was a common wobble box speed. I was going to change the header drive pully on the left hand rear end to a smaller one to reduce the wobble box speed. The table auger or header conveyor drive I was not going to touch. Could someone please advise me of the N6 wobble box speed or header drive speed. What does everyone think would be the best option in fixing this vibration while keeping the crop feed in even.
Wheel Tire Vehicle Sky Motor vehicle

Kind regards Scott
 

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Scott, it's not dependent on combine model, but rather header (front) model, so the wobble box speed is about the same from combine to combine. Really, there's not much difference between fronts either.

For example, standard sickle speed for a rigid or flex 500 head is 617 rpm. A 300 is about the same. The thing is, you can change the drive sheave on the end of counter shaft to slow or speed up the sickle speed. I'm guessing you need to come up with a little smaller diameter drivesheave to get the sickle speed down, if that speed is sufficient to cut the crop cleanly.
 

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Discussion Starter · #3 ·
Thanks TBK for your reply and help. That's good to know. I was hoping it would have been slower which would explain the vibration. Yes I could slow it down and hope it still cuts properly at up to maybe 3.5mph. Maybe the box isn't right. I did check that the sickle wasn't binding last season. It wasn't getting hot anywhere. Thanks for taking your time to help me out. Cheers
 

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Are there any cracks in the frame around the wobble box or the structure of that side of the front. Need a draper on that girl
 

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Discussion Starter · #5 ·
Not that I have seen but I will certainly check it. Thank you for the suggestion. Cheers
 

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Another thing to check is the shafts...I put a 327 on an r72 last year and it shook like crazy, I then spent a while adjusting and lubricating the wooden blocks on the shafts and making them as straight as I possibly could and now it actually runs pretty smooth. I also had to change one of the wooden blocks.
 

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Discussion Starter · #7 ·
Thanks Bap for another suggestion, I have checked the box again and everything is tight. The sickle will turn over by hand. There is no cracks anywhere I can see. The rear drive shaft had one wooden block which I replaced with a nylon block with no slack before last harvest. It may well be a slight bend in the shaft though. Someone mentioned to me at last harvest that it could be the shaft because it didn't have a uni joint where it attaches to the combine. It has the slide over spline attachment. The same person thought a dampner over the lh end of the shaft may help. What has your header have with the shaft attachment? Does it have a weight type dampner? Kind regards Scott
 

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It is just a spline coupler...the shafts didn't quite line up exactly so I checked those bolts that hold those pieces that the wooden blocks bolt to and a couple of the bolt holes were slotted.

I then screwed around with those until the spline would just slide on without having to tap it or anything. It still isn't perfect but it made a hell of a differrence. Still running it this season without any ill effects.

Just a thought...hopefully you can find a way to improve it without too much trouble...mine didn't just get silky smooth however when the hopper gets about half full it is pretty darn smooth...empty it still shakes a bit however not nearly as bad as when I first hooked it up.
 

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Discussion Starter · #9 ·
Thanks a lot for helping me Bap. That could be what's wrong with it. It doesn't slide on easily unless it's in the correct rotation position. I will move that block to get it straighter. It will certainly be easier than the other options. Cheers
 

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Where the end caps are on the wobble box for the outer bearings there are shims to keep the bearing within spec for play. They are a timkin bearing in there. They may have not gotten it shimmed right and has to much or is to tight. Get in there with a bar and check for excess play front to back. And that your adjustable bolt that attachs to the knife isn't to high or low creating a tight knife. Take the belt off and turn it by hand. There should be no binding at any point in the knife stroke. The pulley is weighted and is on a key which keeps things balanced and in time. Check if they maybe forgot the key. Many try and be their own mechanic with these and there are rules that get broken of doing it right the first time taking their time. Rebuilt means many different things to many people lol.
 

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Discussion Starter · #11 ·
Hi Doolittle thanks for your very helpful and detailed reply. I will look at it carefully. I am not a very good mechanic and a lot of that is beyond my abilities. I am willing to get a mechanic out to check it. Thanks so much. Scott
 

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You are really holding that machine back with that front as well as possible feeding issues. Any reason for going for a tin front instead of a draper?
 

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He, he...well I know that wasn't aimed at me but for a grand I got a 27 foot header that works well in heavy cereals...250 hours and counting with just changing a few sections.
 

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Discussion Starter · #14 ·
Silverrod, price and availability. It had a 36foot mcdon belt front on it when I purchased the combine. I sold it because it was too big for my type of land. I couldn't find any belt fronts to replace it with at the time.
 

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Discussion Starter · #15 ·
He, he...well I know that wasn't aimed at me but for a grand I got a 27 foot header that works well in heavy cereals...250 hours and counting with just changing a few sections.
I had to pay many times more than that for mine sadly. There just isn't the number over here. It's about economics of the business the decisions we make. I would love a new gleaner too but to harvest 200ac a year it doesn't make financial sense.
 
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