PTO Shaft Balance

welder1 · Jun 8, 2010

New tractor owner , operator here. It seems like the pto shaft on my rotary cutter seems to have excessive wobble or runout. Is there a way to get it to run more true or is it not a problem?

RoyJackson · Jun 8, 2010

At 540 RPM, I don't think balance is a big issue. Plus, you're probably looking at the plastic guard, rather then the shaft.
I've never heard of implements wearing out a tractor PTO by being imbalanced.
So, I suggest you not worry...keep an eye on the implement, not the driveshaft.

TripleR · Jun 8, 2010

Pretty much agree with Roy. Are you getting a lot of vibration?

Transit · Jun 8, 2010

The shaft guard and end shields should never be spinning, they should be tied to keep from spinning. They may wobble but never spin.

welder1 · Jun 8, 2010

I bought it used and part of the plastic shaft guard is gone. Went to my local TSC yesterday to get one and they didn't have one. No vibration after it starts spinning but it thrashes a little bit on engagement.

RoyJackson · Jun 8, 2010

Transit said:
The shaft guard and end shields should never be spinning, they should be tied to keep from spinning. They may wobble but never spin.

Yeah, but my chain loops went years ago so mine spin (not in sync with the metal drive shaft, but it catches on occasion).

RoyJackson · Jun 8, 2010

welder1 said:
I bought it used and part of the plastic shaft guard is gone. Went to my local TSC yesterday to get one and they didn't have one. No vibration after it starts spinning but it thrashes a little bit on engagement.

Rotary cutters thrash about a bit until those blades pivot out. As you know, the blades may not be fully extended initially, so the cutter (not the driveshaft) will be out of balance.
Once the blades pivot out (extend), they smooth out considerably...then you can increase the tractor to PTO RPM. I don't think you've a thing to worry about...

beenthere · Jun 8, 2010

Transit said:
The shaft guard and end shields should never be spinning, they should be tied to keep from spinning. They may wobble but never spin.

And important if an attachment that is running off the PTO and someone is working around the PTO shaft. On a rotary cutter, not of significance, as no one would be running a RC with someone near it on the ground (unless of course one carries riders along on the deck

NOT! )

RalphVa · Jun 8, 2010

I agree with Roy about the low rpm not causing a vibration problem.

The cutters on my LX4 are weird. They seem to very seldom fully extend and flop in unison. So, the thing ends up very slightly out of balance until I hit something solid enough to jolt them into swinging right. I've lubed them with silicone spray to no avail. They just do their thing. SOMETIMES engaging and disengaging at different rpm straightens them out but not always. When they're swinging nicely in unison, the cutter is virtually as smooth as a straight blade lawnmower, but this often doesn't last long.

Ralph

RoyJackson · Jun 8, 2010

beenthere said:
And important if an attachment that is running off the PTO and someone is working around the PTO shaft.

Nobody works around my drive shaft when it's running, including me. My only stationary implement is a chipper and we always approach from the rear.
Even when I have to get near the tractor, I give it wide berth (8-10 feet). With my bad leg, I trip or stumble occasionaly anyway...and I'm not going to be near any rotating equipment if and when I do.

welder1 · Jun 8, 2010

Thanks for the replies. I have alot to learn and this site seems to be the place along with seat time. I really strive to take proper care of my equipment and want it to last.

Chilly807 · Jun 9, 2010

If the PTO shaft is used, check to be sure it's not bent slightly, it happens more than you might think. Mine got bent a while back and had more run out than it should. You'll have to remove the shaft covers and end guards to check it, I ran mine briefly without them in place to be sure of how much run out there actually was.

I ended up replacing the outer shaft, it was pinned in the universal yoke and could be separated without too much trouble.

Sean

RoyJackson · Jun 10, 2010

Chilly807 said:
If the PTO shaft is used, check to be sure it's not bent slightly, it happens more than you might think. Mine got bent a while back and had more run out than it should. You'll have to remove the shaft covers and end guards to check it, I ran mine briefly without them in place to be sure of how much run out there actually was.

I ended up replacing the outer shaft, it was pinned in the universal yoke and could be separated without too much trouble.

Sean

I had one that was slightly bowed. It doesn't take much to make it difficult for the shaft to extend or retract. It's still setting in my outbuilding, I think.

BTW, don't forget to pull them apart to grease 'em once or twice a season.

jayste · Jun 10, 2010

Welder1, just as a mention, when activating the PTO do it slowly but deliberately. This will make things a little easier to start for your tractor as well as the cutter.:thumbsup:

RoyJackson · Jun 10, 2010

jayste said:
Welder1, just as a mention, when activating the PTO do it slowly but deliberately. This will make things a little easier to start for your tractor as well as the cutter.:thumbsup:

Very important info above. Engaging the PTO at a lower RPM (1200-1500) reduces the shock load on both the tractor and the cutter. Much easier if you have a gear tractor, BTW.
Some hydro machines' PTO is on or off...no feathering as you can do with a gear tractor, unfortunately.

buck12 · Jun 10, 2010

RoyJackson said:
Very important info above. Engaging the PTO at a lower RPM (1200-1500) reduces the shock load on both the tractor and the cutter. Much easier if you have a gear tractor, BTW.
Some hydro machines' PTO is on or off...no feathering as you can do with a gear tractor, unfortunately.

Are you trying to start another gear vs hydro TBN war? Not that I am against it. Always fun reading.

RoyJackson · Jun 11, 2010

buck12 said:
Are you trying to start another gear vs hydro TBN war? Not that I am against it. Always fun reading.

Not at all...
Engaging a cutter requires a bit of finese...a "soft" start might be a good description.
Engaging at 1200-1500 RPM may cause the tractor to stall. If the operator has a hand or foot throttle, he can keep it running. Slipping the clutch (this assumes a live PTO, not independent) can ease the start.

Transit · Jun 11, 2010

I let the engine idle and slowly engage the PTO clutch to spin up the hog, than let the clutch out slowly to move the tractor and then bring the engine speed up to PTO speed. :thumbsup:

TripleR · Jun 11, 2010

RoyJackson said:
Very important info above. Engaging the PTO at a lower RPM (1200-1500) reduces the shock load on both the tractor and the cutter. Much easier if you have a gear tractor, BTW.
Some hydro machines' PTO is on or off...no feathering as you can do with a gear tractor, unfortunately.

Agreed. My John Deere has an either "on or off" PTO switch so no feathering while my Kubotas have lever engagement which allows feathering. (the new models may be different) My L5030 also has a clutch which also disengages the PTO, so I will depress the clutch lever, fully engage the PTO lever and then feather with the foot clutch. Now I don't like a clutch on an HST model, but it's there, so I use it. Now my geared Case has a slot half way through engagement where you stop for several seconds to let the PTO spool up and then you engage fully and this works great. You don't have to touch the clutch and can engage while underway.

Feathering, no matter how it's done sure makes mowing easier on the equipment and nerves, at least for me.