62c mower belt flapping

[ADin]

Some more data,

I wasn't able to break the nut loose on the middle sheave (no corrosion, just too dang tight) and would also just loosen the blade nut underneath. So I left it and I cleaned and sharpened blades, and reassembled everything. Improving the 1 sheave I could get off did not seem to make much difference.

I've been thinking about new experiments the past few days and while I got into a oil change on the tractor today I tried a few of them.

First was to remove the blades to eliminate blade problems and reduce spindle effects - result was no change in flapping.

I then observed flapping at various rpm speeds under no load and without blades. Flapping was still significant across the entire rpm range. At low rpms the tensioner actually appeared to travel further than at higher rpm. To me this all but eliminates the spring as a cause as although the spring is acting as a low pass filter, the oscillations are significantly higher frequency than than what the spring can react to and while a stiffer spring might shift the frequency response up a bit, I don't think it would move it enough.

I also noticed that whatever was causing the flapping had a fixed periodicity to it (not a big surprise) and that changing the rpms slowly I could cause the harmonics to align or destructively beat causing either a near perfect standing wave (near maximum flap travel) or very little flapping. My feeling is that this all but eliminates the belt at a cause. Sheaves are still the prime suspect.

I removed the deck again and studied the tensioner again since I was a bit surprised to see the amount a travel I was seeing at low rpms and I wanted to eliminate the pto as a source. I measured the travel of the tensioner pully as I slowly hand turned the pto shaft. I discovered that I could cause a min to max travel of about 3/16" in about 1/4 turn of the PTO at certain spots in the rotation, but not in the same spot of the PTO rotation. This eliminates the tractor and PTO box as primary source. Knowing that this 3/16" movement over a such short distance by hand turning the PTO will be amplified significantly as the belt speed is increased, I think this has to ultimately be the problem (or indicative thereof).

The tensioner pully movement coorelated to the very small wobble in the middle sheave I was not able to remove before. I went to work again trying to remove the sheave nut and this time with two breaker bars on the top/bottom nuts and a 2x4 to act as a third hand to help hold the blade fixed I was able the loosen the nut. I found this was the worse sheave and that the "thickness" varied over short distances which would cause the apparent sheave radius to grow or shrink. I tried to make uniform, but there is only so much precision one can do with a vise and I didn't dare try hammering. I reassembling and still have a bit of wobble in the sheave. The min to max travel of the tensioner pully is now about 1/8" versus 3/16" before. Not unexpectedly I still have belt flapping, although I believe it may be subtly reduced.

I think I will break down and buy 1, possibly 2 sheaves at this point. Anybody know the cost off hand? Or more importantly where I can find a non-deere cross referenced part. Its no telling what Deere will want to charge for 1 of these sheaves.

Megatractor - I would be curious to know if yours is similar, though perhaps worse. If you get a chance all you would need to do is to just disconnect your pto and hand turn your blade at the discharge side and notice if your tensioner has much travel. I found a small 90 degree straightedge standing upright against the tensioner pully while you rotate makes it easy to see.

Based upon the above, does anyone have any other thoughts or experiments before I drop any money on the sheaves?

 

[megotatractor]

Wow, nice to have an engineer working on this. Have you applied with Deere?
I have already looked up part #s and prices on almost all 62c parts, bearings, sheaves, seals, etc.. the sheaves part # M140059 is $22.75 each. Sorry I don't expect to have time to fiddle with this until this winter, sounds like you're on it. I'm sure many owners are watching your efforts closely and appreciate it.

 

[ADin]

My problem solved - The sheaves were in fact the culprit.

After a short wait for the dealer to get the sheaves in stock (Hmm, reading these boards one would think JD dealers always have basic parts in stock - maybe it's just me...), I switched out two of my sheaves and the belt flapping is now gone, or at least 80-90% of it. For curiosity I would still like to see/hear a new unit for comparison, but its worlds better and I believe everything else would only make subtle, if any improvements at this point. Definitely smoother with less vibration, and quieter (or at least a more pleasing hum) versus what sounded more like a rattle before. I think I might have gotten by with only replacing one of the sheaves, but at this point the effort to confirm didn't seem worth the cost of the $23 sheave.

Interestingly, I measured the new sheaves with the calipers before putting them on and they also had almost as much variation in width as well although it was distributed more gradually around the disk. However, the movement of the tensioner was greatly reduced so there must also be variations in the inside 'V' groove of the sheaves causing problems which are all but impossible to measure. I'm not sure what the root failure mechanism was, but the only two options I can think of it are that either the sheaves wear unevenly over time or that some event such as hitting a stump is able to cause belt forces sufficient to widen the 'V' groove. Both seem unlikely, but it is the best I can come up with.

Megatractor - Let us know what you ultimately find when you get around to it. Hopefully, you will get lucky and it will also only be a 15 minute, $25 sheave fix.

 

[megotatractor]

Yea, IF I can get those darn sheave nuts loose. I have two sheaves that have visibly noticeable wobble in addition to rust spots. I've been running with the guards removed to keep an eye on the belt flap. The flap is intermittent now and I wonder if that is due to the differing sheave diameters getting into and out of synch with one another? I'm thinking as you said I should order my sheaves now and install them before end of season to see if it is cured.

 

[ADin]

A couple of points I found necessary to get the sheave nut off:

1) Brace and stand the deck on its side so you can get to both the top/bottom nuts simultaneously.

2) Use a block of wood to keep the blade from turning

3) Use a second block of wood to keep one of the OTHER two blades from turning and DO NOT remove the tensioner spring yet. This will help hold the sheave in position via the belt.

4) Use two breaker bars to carefully applying pressure (impulses) to both the top nut and the blade nut simultaneously, in the same direction. This is equivalent to simultaneously tightening the blade nut while loosen the sheave nut and helps prevent the bottom nut from just loosening up.

For me it required all four points with the addition of step 3 which finally allowed me to get the nut off. I did not have any corrosion so even with soaking the sheave nut in penetrating oil you may still require some luck.

One last comment, it is only variations of radius on a single sheave which one needs to worry about, not the radius variations from one to the next as this will only translate into a slight blade tip speed variation, but not vibration problems. Therefore, assuming this is in fact your problem, you can watch the tensioner movement to help isolate the bad sheave, and confirm with replacing just the one. Like I mentioned above, I can't imagine many events which would lead to sheaves being damaged, so I suspect it would not actually be common to have multiple sheaves affected.

 

[megotatractor]

Youtube video of my tractor mowing and belt flapping. -and also someone wanted to hear another 2210/62c what it sounds like.

YouTube - beltflap

 

[megotatractor]

I have had NO LUCK reducing the belt flap. I tried replacing a sheave. Both outer sheaves seem to wobble. Could the spindles be bent???? I have hit rocks and gotten sticks stuck iin the past, but then the belt flap seems to have gotten progressively worse, it would have been a sudden change had anything happened to the spindles. Belt worn unevenly?????? Perhaps, as I have accidentally gotten grease on the belt in the past could that have made the belt "sticky" and should I try to degrease the belt???? This seems the next step, cleaning and degreasing the belt see if that does anything. Maybe that should have been first? LOL

 

[ADin]

What do you mean by the sheaves seem to wobble? Do you mean if you rotate them that they are our of round (most likely sheave) or that you can grab one and move it without rotating (worn spindle/bearings)? Can you quantify the wobble somehow, as a small amount is probably normal?

Looking at the spindle I replaced it seems hard to imagine how you could bend without noticeably cracking the housing, bending the deck or grossly affecting the cut. My first inclination is that even IF you did bend a spindle, unless the bearings were damaged, the result would be one of horrific deck vibration with belt flapping being a secondary side effect. I'm definitely not well versed in belt deterioration symptoms, but I don't see how either a sticky or slick spot would cause flapping. If you have worn spots (you said earlier the belt visually looked ok) or somehow the belt is more stretchy in spots (seems far fetched) then I could see vibrations occurring. If you have/had lots of grease on the belt then cleaning can't hurt.

Did you disconnect and rotate the pto shaft and monitor the movement of the tensioner arm? If sheaves, bent shaft, worn belt, etc. was the cause then you should see movement in tensioner arm (btw, for this test be sure to rotate the pto shaft by hand and not one of the blades as I believe you will get a more accurate reading; rotating the blade farthest from the discharge chute would be second choice). If you observe large moves in the tensioner arm or significant moves over a relatively short distance then you can at least narrow down. The wobble you describe doesn't sound good. Are either of the two outer spindles wobbling include the one you replaced or did you replace the center and the outers are still wobbling? I would want to try and determine whether the wobble was normal, wobble due to sheave, or wobble due to bearings. I still can't much imagine the spindle being bent, but possibly worn. You could also always try swapping the spindle between one which wobbles and one with doesn't to see if it follows the spindles.

Lastly, if you do have out of round sheaves you may notice very different amounts of flapping depending upon whether the wobbles are aligned, similar to a car going over two speed bumps where the front tires hits one of the speed bumps at exactly the same time as the rears also hit the second. I say this because if you have two sheaves out you may get slightly different results every time you do anything which causes one of the sheaves to rotate relative to the belt.

I would love someone to chime in on symptoms of belt wear on mower decks, otherwise I would focus on the sheaves/bearings a bit more. If you can correlate back to tensioner arm movement I'm certain you can pinpoint. E.g. at the point of maximum tensioner movement you can mark the belt/sheaves and then continue rotating the pto to look for the next point of max movement. You should be able to then see whether the movement aligns to the markings on the sheaves (making a rotation) or the markings on the belt hitting the next sheave.

 

[megotatractor]

Wobble as in ; removing the belt, spinning that blade quickly by hand, observing the sheave from directly on edge and seeing the sheave appear to wobble like a warped LP vinyl record.
As to the belt I can measure that it is slightly worn from the specifications on width/thickness. I'm guessing it is conceivable it has worn unevenly. As I have in the past gotten branches stuck in the blades and stalled the engine, this might have caused a very slight flat spot which has gotten worse over the years?
As you say ADin, I wish someone with 500 hours on their belt or experience with a worn belt would chime in???

 

[ADin]

Yikes! If I'm picturing what you are describing with the amount of wobble then that doesn't sound good at all. I think you can confidently stop worrying about your belt (you can also eliminate mower deck and spindle housings). A very small amount of wobble may be normal. To calibrate us, I would check whether the wobble is unique to 1 spindle or all and I would debug something like:

1) If only one is wobbling, then focus here and next determine whether it is sheave, spindle, or bearings. (a) Swap with your newly purchased sheave (if not already done) to eliminate sheave. (b) If wobble correlates to full rotation of spindle/sheave then it is more likely related to the spindle. You can remove and check with straight edge, micrometer for wear, or simply roll on flat surface (e.g. tablesaw top) with spindle bottom hanging off edge such that it should roll freely and you can see if bent via light showing between spindle and table surface. (c) If you have excessive play or damaged bearings you'll need to inspect, wiggle, etc to determine. Bearings are the only thing I can imagine that are not be directly related to rotation position of the blade.
(d) if in doubt you can always swap spindles to see if the wobble follows the spindle and if not replace the bearings.
(e) if spindle is bad it could have damaged the bearing and I would replace for piece of mind

2) If all are wobbling then what you have is either normal (doubtful), or almost certainly bearings. The odds of two or more bent spindles is very low in my opinion. Odds of worn or damaged bearings much higher.

You could still some kind of contribution from a worn belt, but I'm pretty confident its effects would be dwarfed by a "warped LP vinyl record" spinning sheave.