Go BottomSyncronizing the PTO driveline
 | AnnBrush
Join Date: Mar 2004 Posts: 463 Troy OH 
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2006-11-02 136524
Could someone please remind me how to "syncronize" the PTO driveline to reduce harmonic distortion on the generator - I thought there was a thread on this board but I cant find it. I have a metric driveline (curved triangular tube sheath - for extension - on the PTO, thus three possible orientations, and two cross bearing thingys on the opposing universal joints. I realize this only applies when the driveline is operated such that there are bends in the universal joints (height difference) but need the information anyway.
Many thanks Ann
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| AnnBrush
Join Date: Mar 2004 Posts: 463 Troy OH
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2006-11-03 136565
Bump ....
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada 
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2006-11-03 136566
I wish I could help, but I just don't know.
I know that the better gen-sets have a low harmonic distortion number, but I always assumed that was something contained within the unit itself and not related to the PTO drive line.
I do know that the drive line should run as straight as possible to the generator. ....
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2006-11-03 136569
Soory Ann, I didn't see this until just now.
It's one of those cases where a cutesy saying helps to remember something.
"The entire driveline must see eye-to-eye or the parts will never get along with each other."
The "eyes" or loops that hold the U-joint on any given shaft must be in the same plane, if they are rotated out of phase it will cause a harmonic vibration.
Your driveshaft should look the one below.
O=================O
If it looks like the one below, it will never run smooth.
O=================[
Best of luck. ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2006-11-03 136570
Good info Murf. I just want to confirm you are saying the "X's" that form the CV joints need to line up.
I wonder if you can run your PTO drive shaft out of phase in Sedona, AZ and not notice it. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2006-11-03 136572
Mark, you are correct.
It is the pivot points that the X's form that must be in unison.
I forgot to mention, extended use of a heavy, out of synch. or even just bent driveshaft can also get spendy after a while. Likewise a badly out of balance implement like a bush hog, even if just from broken or bent blades, can cause damage to the tractor's output shaft and the bearings it runs on.
I saw a guy bush-hogging a field this summer, the unit was shaking so bad you could see the deck moving from the road. I stopped to point it out to him. When we lifted the deck up there was about 2" of one blade broken off!!!
He thanked me and asked for a business card. He called me the next day to thank me, he spent $40 on a new set of blades and was astounded at the diiference. He said the numbness in his feet had even stopped!! LMAO!!
Best of luck. ....
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2006-11-03 136576
Most single u-joint drive shafts (vs. a double caradan-type) with a joint on each end are designed to run at about 2 degrees total each out-of-line with very slight or no vibration. At about 5 degrees total or 2.5 degrees each is when you start to see vibration.
The vibration is caused by the joints being out of phase, that is, like was mentioned above the yokes on the ends should form an X to cancel the effects and be in-phase. Out-of-phase is a condition where as the shaft turns the yoke it drives the u-joint at 1.5 RPM's times faster than the input speed through 90 degrees of rotation. The next 90 degrees it slows down by 1.5 times RPM, speeds up, and slows down resulting in vibration.
As an experiment, take a 1/4" or 3/8" ratchet socket universal with two extension shafts and rotate one shaft as the "input" with your fingers. Allow the other "output" shaft to make a sharp angle and observe/feel the output shaft--it will feel like it's jerky or speeding up and slowing down every 90 degrees. If you were to connect another unversal to the input shaft and rotate it, to a certain degree, the output shaft would be nearly vibration-free.
To cancel or reduce vibration, you can have a double cardan joint on one end (which is two u-joints housed in a cast housing) and a regular u-joint on the other end.
Short of that, you may want to consider using a "constant velocity" or "CV" joint that uses balls in a cage (used on front wheel drive cars) that deleivers vibration-free power. There are Ag applications for these type of shafts with CV joints but can be expsensive.
U-joints are not considered "constant velocity" by definition since they are by nature out of phase if not phased with another u-joint on the other end of the shaft. ....
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| AnnBrush
Join Date: Mar 2004 Posts: 463 Troy OH
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2006-11-04 136584
OK Thanks guys, I now have mine looking like this:
]---------[
such that the opposing yokes on each shaft end of the universal joint are in the same plane.
....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2006-11-04 136592
Pull the shaft apart and turn one end 90 degrees and stick it back together. Like this:
O---------------[ ....
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| DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada
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2006-11-04 136593
Boy am I confused......... ....
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| earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2006-11-04 136594
Well, there was a chance I got my info wrong since it's been a few years since I've done hands-on. But along with wracking the noggin' and some cursory investigation on the Web, the results were, well... mixed. Some sites didn't address rotating the yokes 90 degrees; some did. I looked at my Dodge Ram driveshaft and the yokes were aligned--but that doesn't really mean much since having the driveshaft in near perfect alignment the driveline path is aligned straight through from the transfercase through to the axle. Having lifted four offroad Jeeps over the years 10-12" I stand by my earlier comments as having to out-of-phase or rotating the yokes 90 degrees to cancel vibration. ....
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| AnnBrush
Join Date: Mar 2004 Posts: 463 Troy OH
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2006-11-07 136685
Got it all sorted out, seems like the triangular shaped shaft I bought (so-called metric shaft) can only be attached in one orientation anyway (the sides are slightly different) so the driveline lines up perfectly as below:
]==============[ or if you are looking at it differently O===========O
I suppose it wouldn't make much difference on an ATV or truck if the orientation was ]===========O AND the shaft was perfectly balanced but in a generator application there would be slight speed ups and slow downs and that would affect your generated power quality. On an ATV you would be totally unlikely to notice it - or would you? ....
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 | Chief
Join Date: Jul 2003 Posts: 4299 Southwest MiddleTennessee
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2006-11-07 136686
Murf and company, can you go over this again? I am all flumuxed and confused as well. ;O) ....
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 | s chrand
Join Date: Aug 2004 Posts: 77 Mid-Michigan
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2006-11-07 136687
Try the Wikipedia web site... it has a fairly good description of the situation.
In essence, as the angle between the drive and driven shafts increases from 0 degrees (straight line, no bend), the relative speeds of the two shafts vary from one another, first speeding up, then slowing down. The greater the angle between the shafts, the greater the maximum difference in rotational speed. By keeping the two universal joints lined up as Murf described, the effects nearly cancel themselves out, but not quite. The effect isn't symmetrical, so the slowdown at one end can't quite make up for the speed up at the other end.
David ....
Link: Wikipedia
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 | oneace
Join Date: Mar 2004 Posts: 1490 south central pa 
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2006-11-08 136722
Really the only time you would have to worry about the phase of your drive line is if you were building or repairing it your self. When coming from the manufacturer they will be phased correctly. All new and modern pto shafts regardless of shape will go together just one way. I have run across some older square shafts that are worn that will go in any direction. Basically you want your shaft yokes to be in line with each other. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2006-11-15 136922
Chief, did you (and everyone else) get this straight after looking at the Wikipedia info.?
Best of luck. ....
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| Chief
Join Date: Jul 2003 Posts: 4299 Southwest MiddleTennessee
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2006-11-15 136933
Yep Murf...........clear as mud now! ;O) Basically what I was thinking but the terminology being used threw me off. Great link by the way s chrand! Thanks! ....
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