pto shaft question

gbs

Member
we have several trail type pto driven pieces of equipment,problem i'm running into is when i turn with the pto engaged if i turn a little to short the shafts will shutter with the exception of one peanut combine it has a short shaft like the haybine does, the rest are long shafts,all them have the u-joints lined up parallel except the peanut combine i mentioned before it's joints are 90 degrees apart it can be turned about 70 degrees either direction before the hitch binds it never shutters turning ,should the rest be 90 degrees off also ???the one's that shutter have u-joint yokes that are long and wide to allow for being run at an angle.
 
The PTO shafts need to be in phase, so that means the yoke on both ends of the shaft need to be lined up. Is your drawbar set right? How tight of a turn are you making?

Donovan from Wisconsin
 
A u-joint essentially has a "gear ratio" that follows a sine wave pattern when running at an angle. In other words, the output speed goes up and down relative to the input speed. An "equal angle" driveline always has two u-joints that run at the same angle and are in phase with each other. This results in the speed ratios canceling themselves out and the output speed then equals the input speed of the system. (A CV joint works exactly the same way except it two u-joints bundled into a single package.) However, if your driveline has only one u-joint that bends when you turn the input speed going into the implement is pulsing up and down. This is what causes the chatter.
 
Are the ones making the noise a 2 joint shaft? And the others a 3 joint shaft? Everything that I had with the 2 joint shaft had that problem, but not with the 3 joint shaft . Location of the second joint makes if you have the problem. And the 2 joint machines are generaly the cheaper designed and cheaper sold machines.
 
You're right. If your hitch pin is centered between two u-joints then you should be able to have a chatter-free system. If you have one u-joint right at the tractor and one way back on the implement then you can expect vibration during turns.
 
Yes the ujoints have to be phased with each other and are you hooking up to the middle of your drawbar or to one side?
I have seen an exception on a Case ground driven hay rake where the drive shaft from the drive wheel to the gearbox was 90° out of phase. The angle on the ujoints always stayed the same and when turning it over by hand you could feel it bind.
 
2 of the peanut combines have 5' long shafts with u-joints at each end,the haybine, potato digger and other combine have short shafts close to 3' with u-joints at each end all are center pull,all have the yokes lined parallel to each other except the combine with the short shaft it's yokes are 90 degrees apart, it's the only one that doesn't shutter when turned more than 10 degrees ,the short shaft machines shafts are about centered on the draw bar pivot point,all are pulled from the 3 point hitch to enable the machines to be raised and lowered which also can add to the problem ,the haybine doesn't shutter as bad when turned to the left the rest of them it don't matter they do it either direction
 

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