Wobble boxes
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wafarmer, Have a look at the "Gleaner R62 photos" thread for Rolf's photos.
Click the top link for a large number of mods done to the R62.
In the top row of photos you will see the wobble box on the R62 500 series flex header.
A heavy steel flywheel, about 18 kgs [ 40 pounds ] weight, has been mounted into the wobble box V belt drive pulley.
The recess in the V belt drive pulley was lightly machined to give a good firm fit and seat for the flywheel and only three 3/8 bolts are needed to keep the flywheel in place.
The inertia of the added weight of the flywheel smoothes the rotation of the wobble box right out and eliminates the rapid stop / start effects of the wobble box as the knife reaches the end of it's stroke and then reverses direction.
The knife action is also very smooth, again without the stop / start shock of the knife that is readily seen on most knife drives and this of course provides greatly increased knife life.
Another flywheel as photoed is installed on the drive shaft at the back of the header.
This also helps smooth out the fluctuations caused by the wobble box greatly prolonging belt life which we now only replace every 3 or 4 seasons after some 1200 acres of cereals and another 1200 acres of flex header work in Lentils each season.
The rear flywheel also preserves the splines on the header drive shaft hook up point by giving a much smoother drive and the combination of the two flywheels giving a smooth knife drive has now given us a belt life of some two or three full seasons per belt.
The first three feet of the knife wear plates that support the knife should be set well back as the knife moves fore and aft by some millimetres as the wobble box knife drive arm swings through an arc during it's stroke.
Not having this for and aft clearance can lead to knife binding during a part of the stroke and heavy driving for the wobble box and maybe regular breakage of the knife near the head.
Just leave these plates and hold downs loose. Swing the knife through the full stroke a few times.
this will push the loose wear plates back to accommodate the swing arc of the knife drive arm and fore and aft movement of the knife.
tighten the hold downs and you will have the necessary clearances.
Check also whether the arc that the arm moves through is absolutely dead flat in line with the knife bar.
A lot of wobble boxes are not dead level with the knife bar and wobble box drive arm will then lift the knife or force down the knife at one end of the stroke.
Also the AGCO knife heads into which the thread on the bearing housing is screwed into are usually not in line with the knife leading to the knife lifting and not seating on the guards some two feet along from the head.
When a wobble box and knife is set up like this, you can see the knife vibrating some two feet out along the knife bar from the wobble box when the combine is running at full revs.
This can be corrected by heating the knife head and very slightly , emphasis on slightly bending, the threaded portion of the knife head to ensure that the knife seats on the guards all along the knife.
It's a very subtle touch required here.
We have found this out of line problem with both the AGCO knife heads we have been through in the last ten or more years.
I now make our own heads out of a piece of 1. 1/2" x 1. 1/2" x 1/4" angle iron using a cutoff wheel to cut it down to shape as in the AGCO heads.
A couple of nuts welded onto the angle iron provides the female thread for the bearing housing thread.
Only made one so far as they go for years when the wobble box and knife alignment are set up correctly.
Cost less than ten dollars and takes about two hours to make and is tougher and more durable than the real thing and you just use the gas torch to heat up the threaded end to bend that tiny adjustment to get the stroke exactly into line with the knife bar.
AGCO wobble boxes are very simple to rebuild although with the flywheels and correctly set up knife I don't get much practice as we have only done one major rebuild, just a full bearing replacement in the last ten or twelve years.
If there is even a small knock at the wobble box when under load or even unloaded, the knife is too tight in some spot of it's stroke or the trunnion bearings on the front and back of the box need a shim taken out to take any slack out of the tapered roller bearings.
Essential that this is done and can be done in about an hour without removing the wobble box.
Just unbolt and lift off the top plate cover to get access to the trunnion bearings housings.
Again this has to be done about ever one and a half seasons on our wobble box which as above does about 1200 acres of cereals and about 1200 acres of heavy flex header work, often in very green stemmed lentils per season.
Hope this long winded screed helps.
Cheers
Click the top link for a large number of mods done to the R62.
In the top row of photos you will see the wobble box on the R62 500 series flex header.
A heavy steel flywheel, about 18 kgs [ 40 pounds ] weight, has been mounted into the wobble box V belt drive pulley.
The recess in the V belt drive pulley was lightly machined to give a good firm fit and seat for the flywheel and only three 3/8 bolts are needed to keep the flywheel in place.
The inertia of the added weight of the flywheel smoothes the rotation of the wobble box right out and eliminates the rapid stop / start effects of the wobble box as the knife reaches the end of it's stroke and then reverses direction.
The knife action is also very smooth, again without the stop / start shock of the knife that is readily seen on most knife drives and this of course provides greatly increased knife life.
Another flywheel as photoed is installed on the drive shaft at the back of the header.
This also helps smooth out the fluctuations caused by the wobble box greatly prolonging belt life which we now only replace every 3 or 4 seasons after some 1200 acres of cereals and another 1200 acres of flex header work in Lentils each season.
The rear flywheel also preserves the splines on the header drive shaft hook up point by giving a much smoother drive and the combination of the two flywheels giving a smooth knife drive has now given us a belt life of some two or three full seasons per belt.
The first three feet of the knife wear plates that support the knife should be set well back as the knife moves fore and aft by some millimetres as the wobble box knife drive arm swings through an arc during it's stroke.
Not having this for and aft clearance can lead to knife binding during a part of the stroke and heavy driving for the wobble box and maybe regular breakage of the knife near the head.
Just leave these plates and hold downs loose. Swing the knife through the full stroke a few times.
this will push the loose wear plates back to accommodate the swing arc of the knife drive arm and fore and aft movement of the knife.
tighten the hold downs and you will have the necessary clearances.
Check also whether the arc that the arm moves through is absolutely dead flat in line with the knife bar.
A lot of wobble boxes are not dead level with the knife bar and wobble box drive arm will then lift the knife or force down the knife at one end of the stroke.
Also the AGCO knife heads into which the thread on the bearing housing is screwed into are usually not in line with the knife leading to the knife lifting and not seating on the guards some two feet along from the head.
When a wobble box and knife is set up like this, you can see the knife vibrating some two feet out along the knife bar from the wobble box when the combine is running at full revs.
This can be corrected by heating the knife head and very slightly , emphasis on slightly bending, the threaded portion of the knife head to ensure that the knife seats on the guards all along the knife.
It's a very subtle touch required here.
We have found this out of line problem with both the AGCO knife heads we have been through in the last ten or more years.
I now make our own heads out of a piece of 1. 1/2" x 1. 1/2" x 1/4" angle iron using a cutoff wheel to cut it down to shape as in the AGCO heads.
A couple of nuts welded onto the angle iron provides the female thread for the bearing housing thread.
Only made one so far as they go for years when the wobble box and knife alignment are set up correctly.
Cost less than ten dollars and takes about two hours to make and is tougher and more durable than the real thing and you just use the gas torch to heat up the threaded end to bend that tiny adjustment to get the stroke exactly into line with the knife bar.
AGCO wobble boxes are very simple to rebuild although with the flywheels and correctly set up knife I don't get much practice as we have only done one major rebuild, just a full bearing replacement in the last ten or twelve years.
If there is even a small knock at the wobble box when under load or even unloaded, the knife is too tight in some spot of it's stroke or the trunnion bearings on the front and back of the box need a shim taken out to take any slack out of the tapered roller bearings.
Essential that this is done and can be done in about an hour without removing the wobble box.
Just unbolt and lift off the top plate cover to get access to the trunnion bearings housings.
Again this has to be done about ever one and a half seasons on our wobble box which as above does about 1200 acres of cereals and about 1200 acres of heavy flex header work, often in very green stemmed lentils per season.
Hope this long winded screed helps.
Cheers
Darn! Forgot a bit!
Make sure that self aligning ball type bearing under the drive arm and at the bottom of the box is tight in it's bearing plates.
Any movement here and trouble will rear it's head in short order.
The ball can wear those bearing plates quite a lot so we have had to replace the plates a couple of times over the last few years but now I stick some locktite onto the bearing surface of the plates, turn the box over to get the bearing into position and tighten the bearing plate bolts up.
If there is visible wear on the ball then regardless, it will move in even new bearing plates so replace the ball type bearing if wear is visible.
No further problems with wear in that bearing area since using the locktite to anchor things down.
Cheers.
Make sure that self aligning ball type bearing under the drive arm and at the bottom of the box is tight in it's bearing plates.
Any movement here and trouble will rear it's head in short order.
The ball can wear those bearing plates quite a lot so we have had to replace the plates a couple of times over the last few years but now I stick some locktite onto the bearing surface of the plates, turn the box over to get the bearing into position and tighten the bearing plate bolts up.
If there is visible wear on the ball then regardless, it will move in even new bearing plates so replace the ball type bearing if wear is visible.
No further problems with wear in that bearing area since using the locktite to anchor things down.
Cheers.
Joined
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224 Posts
I am running a 400 series on an R-62 and am going through wobble boxes about every 500 acres. It is costing me a small fortune and would like to remedy the problem. Any ideas? A Macdon is out of the question, so I need to try and make this work for a few more seasons.
Wafarmer, Listen very carefully to Rom---- every word he says pertaining to a wobble box on a Gleaner is the gospel truth !! I have modified my 800 30ft just like he said to and it could not work any better. That Aussie know's what he is talking about, I just wish he would teach the engineers at Hesston how to build a combine! Good luck Bigboy
Joined
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224 Posts
Thanks for the info. The wobble boxes were rebuilt by a local dealer, and I haven't had them apart. The Gleaner heads just don't seem to run smooth. So I will look into that, especially the flywheel mods. We have added weights to shafts before and it makes a big difference. The real problem is my head is pretty well shot. But like I said, it isn't in the budget just yet for an upgrade. But, I will do what I can and take Roms advice. Thanks guys.
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