NH 66 Knotter Clutch

Dave41A

Member
Good afternoon: I own an engine-driven NH Super 66 baler, with Wisconsin TFD engine. Last week I baled 115 bales and broke the flywheel shear bolt. I re-timed the baler and then I baled only 60 or so bales before it broke again. Then 15. Now it will break on the first bale.

With the baler in the shed and rotating things by hand, it is clear that the knotter shaft is not driving the needle yoke to the "home" position. Both the manual and the various pictures I have looked at online show the knotter shaft arm and needle yoke rod in nearly a straight line when the yoke is home. If anything, the knotter shaft arm should be a little past "bottom dead center" between knotter cycles. I can manually move mine to this position, and it "clicks" into this position when I pull back on the needle yoke rod by hand. Please see the pictures: the first is where my knotter arm stops (around 5:30 o'clock), and the second is where it clicks "home" (around 4:30 or so). The knotter arm rotates counter-closkwise in operation, so 5:30 is just before the arm/rod combination reach "bottom center," and 4:30 is just a little bit after.
cvphoto47137.jpg

The above photo shows where my knotter arm stops.

cvphoto47138.jpg

The above photo shows where my knotter arm "clicks" home. This is where it should stop.

I have removed the needle yoke rod, blocked the needle yoke into the "home" position, and just watched the knotter shaft while rotating things by hand. Even with the needle yoke disconnected, when I trip the knotter clutch, the knotter shaft does not make a full 360 degree rotation--rather, it only turns 350 degrees or so, and stops at the 5:30 position--unchanged from when the needle yoke is connected, which makes me think the problem is in the knotter clutch. Further, during operation (with engine or by hand), I can watch the knotter shaft pulse or "quiver" as described by Ron Lines in the thread with the link provided (post of Wed, Sep 7, 2016 4:17 PM). Mine does the same thing, and watching videos of operable balers on line shows that the knotter shaft should not do this. It is as if the knotter clutch is trying to turn the knotter shaft the last 10 degrees or so with each revolution of the knotter shaft sprocket, but cannot. If I manually bring the needle yoke rod home, this pulsing goes away.

So I am thinking that the knotter clutch is not bringing the knotter shaft all the way around, which keeps the needle yoke just enough from home so that a slight bump or other disruption causes the needle yoke to shift, and the plunger safety stop steps in to do its job.

However, I have opened up the knotter clutch and everything is in order--or so it seems. Is there a check or a measurement I can make here for worn parts? The knotter clutch woodruff key is intact and the baler is timed properly, and even remains in time after breaking shear bolts, so it is not skipping links on the knotter drive chain. I can post more pictures if desired.

Thanks in advance for any insight. Dave
Ron Lines question about baler
 
Try tightening the brake before you dive into the clutch. The brake has to hold the needle yoke rod where it stops. If it's not tight enough the rod will creep down from normal vibrations. My 273 starting doing this. A little bit more on the brake springs took care of it.
 
I too would start by checking if the needle yoke brake is holding properly, I have also seen the bolts the hold the disc on the shaft be loose/broken missing,, I did not see that you checked the knotters shear bolt I have seen them partially sheared and cause a few issues,,
 
(quoted from post at 19:37:45 06/14/20) Try tightening the brake before you dive into the clutch. The brake has to hold the needle yoke rod where it stops. If it's not tight enough the rod will creep down from normal vibrations. My 273 starting doing this. A little bit more on the brake springs took care of it.

Mike: Thanks. The knotter shaft brakes seem to be good and tight. No oil on them, either. As I noted, this is not so much an issue of the yoke slipping down (there is a separate yoke brake), but the knotter shaft is not making it all the way around. It does this with or without the yoke rod attached--in other words, even if the needle yoke is disconnected from the knotter shaft, the knotter shaft only goes around 350 degrees when tripped. If it went the full 360, but then slipped back, that would be a different story.

When I had the clutch apart, I saw that resistance on the knotter shaft does make the clutch pawl "grip" a little tighter, so I tightened the brake to see if that would help. I did not observe any difference. Do you have any insight on why the knotter shaft is only turning 350 degrees? Any insight is appreciated. Thanks, Dave
 

Thanks. The problem with the knotter shaft only turning 350 degrees seems to be there regardless of whether the needle yoke is connected or not. The 66 has a separate yoke brake and I am working on getting that freed up & adjusted, but I am thinking that with the needle yokes blocked in the "home" position and no yoke rod connected, the knotter shaft should make a complete 360 when the knotter is tripped no problem. It's not even doing that. I'll try to post some pictures to explain what I mean. Thanks again, Dave
 
Case Nutty: Thanks. I've having a little trouble with the replies ended up with the suggestions, so please bear with me. I have a parts diagram for the S66 knotter shaft and it shows a woodruff key on the clutch drive assembly, but no shear bolts that I can see. That key is in one piece and good condition. Am I missing something? Thanks again. Dave
 
To clarify what I am describing, here is the knotter arm assembly when it is fully "home." Here the clutch pawl is tight against the clutch pawl stop. Notice *both* hex-head brake adjustment bolts are visible. The yoke rod, which normally extends down to the right, has been removed to eliminate that as a source of the problem.

cvphoto47163.jpg


Here is is again after the knotter has been tripped and the baler cycled one full revolution by hand from the flywheel. Note that now the right hand hex-head brake pad adjustment bolt is *not* visible.

The knotter arm has only turned 350 degrees.
cvphoto47164.jpg
It will stay here even if I continue to turn the flywheel by hand. It will "pulse" about 5 degrees or so every time the clutch pawl comes around, as if it wants to finish a revolution, but does not. Under power this pulse makes quite a racket that can can easily hear over the Wisconsin engine with hearing protection on. Clunk! Clunk! Clunk! If I manually pull the knotter arm back the last 10 degrees, this sound goes away.
 
If pulling needle yoke back to home and clunking stops then the needle brake is slipping. The crank arm is hitting plunger stop just a bit.
 
Did you set the clutch stop properly? After your later posts I'd agree it's the clutch. Maybe something worn so that the clutch dog doesn't completely disengage.
 
(quoted from post at 22:47:47 06/14/20) If pulling needle yoke back to home and clunking stops then the needle brake is slipping. The crank arm is hitting plunger stop just a bit.

Thanks. The clunk could very well be the plunger grazing the top of the stop. It goes away when I test-run with the yoke tied fully back and the yoke rod disconnected. However, even with the yoke tied back and the yoke rod disconnected, the knotter shaft does not complete a revolution. This is what has me stumped. Thanks again, Dave
 
(quoted from post at 23:01:33 06/14/20) Did you set the clutch stop properly? After your later posts I'd agree it's the clutch. Maybe something worn so that the clutch dog doesn't completely disengage.

I timed the baler as described in the manual. I have not made any adjustments to the clutch stop. If anything, it seems the clutch is disengaging about 10 degrees too early, and not bringing the knotter arm/yoke rode assembly all the way "home."

Is there an adjustment for the clutch stop? Thanks, Dave
 
There IS A SHEAR BOLT for the knotters, Cannot remember just where it is as the baler left about 76 but I know there is one as we had to replace it a few times. If I remember correctly it is a 3/16" stove bolt anout 1 1/2" long. The manual should show it. Think it is same size bolt as holds wadboard in place.
 
Leroy: Thanks. There is a shear bolt on the knotter drive sprocket at the gearbox (front) end. That was broken and I did replace it. It is either a 3/16 or a 1/4 bolt as you describe. But it is in there and is in good condition. I do not see any on the parts diagram for the knotter shaft itself. I am working from this diagram. But I could be overlooking it as the writing is really small. I got the picture from Messick's.
cvphoto47224.png

Messicks parts diagram
 
The problem may be the knotter shaft.
It may have twisted or bent. I had similar problem, replaced the shaft and that fixed it.
 
Knotter shear bolt 3/16 or 1/4?? Neither, it's a #12 on my 273. Not usually stocked in most hardware stores. The clutch stop is on the left side just below the clutch drum. It's not on the knotter page.
 
Interesting idea. I had not thought of that. It does seem that way. The clutch lets go on one end, but the knotter arm/yoke rod isn't all the way round on the other. Almost like one end is out-of-register with the other end.

Do you know of a way I can check this? Should the key ways line up or is there another indication of damage? I finally got both knotters to tie before this started happening, and would hate to tear it all apart again if I don't have to.

Thanks for the suggestion. I will look into this. Dave
 
I looked at the parts diagram for the 66 and the knotter sprocket drive shear bolt which is on the main gearbox shaft is actually a 5/16-18. So my memory failed me. This shear bolt sandwiches the knotter drive sprocket to the feeder drive sprocket/hub, which is itself keyed to the main gearbox/crank output shaft up near the front of the baler--No's 18, 14 and 13 in the Messicks diagram at the link provided. But this is on the main drive shaft--not the knotter shaft. I do not see any shear bolts on the knotter shaft itself, but there may be a #12 hidden in there somewhere.

Along with the comment on the knotter shaft possibly being twisted slightly, it does seem like I need to adjust the clutch stop to make the clutch stop just a little later, which will allow the knotter arm to push the yoke back just a little bit more, which will get the needles further out of the chamber and the safety stop fully retracted. I will take a picture of this and post here for some guidance on how to adjust it. Thanks, Dave
Main drive shaft parts diagram
 
The only way to check the shaft is to completely remove it, then lay it on a flat surface and roll it. If its twisted or bent it will not roll smoothly.
When you disassemble the knotters make sure you note the exact placement of each part and each shim for reassembly.
Also the disassembly and reassembly should not cause any tieing problems.
 
Check all the gear shaft keys and pins are not partially sheared. There may be a widened out bushing. The metal parts start wearing and create slop. I had to lengthen my needle lift arm because the holes had just worn bigger to the point the rod was getting shorter. The cleevis threads out for adjustment.
 

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