Mowing Kubota PTO Breaking

[Javinka]

I have two Kubota M110x, one pulling a 15' Bushhog RotaryCutter, and a 20' BHRC. My problem is this: We have had to replace the PTO shaft on each tractor at least twice. My question is, is this at all related to operating the attachments at higher than 540? I am leaning towards yes, but I am getting nowhere trying to get a definitive answer. I'm sure once the operators are in the field, they are operating at max RPM. I wam considering having my mechanic put governors on the tractors to keep them at or below 2300 rpm. Any help?

 

[Gary51]

The only PTO I ever broke was on a Ford 7740 was a result of the engagement lever not working correctly and did not feather the PTO on as it should. I would guess that the PTO is being slammed on or perhaps they are making ground strikes with the blades while at running speed.

 

[rbargeron]

I have two Kubota M110x, one pulling a 15' Bushhog RotaryCutter, and a 20' BHRC. My problem is this: We have had to replace the PTO shaft on each tractor at least twice. My question is, is this at all related to operating the attachments at higher than 540? ........am considering having my mechanic put governors on the tractors to keep them at or below 2300 rpm.

I doubt that the shaft speed is a direct cause - the engine doesn't make that much more torque at higher rpm anyway. Impact loading is the more likely cause. And the M110 should be able to soak up quite a whack without breaking. It sounds like the pto shafts may be hardened too much and are brittle. Has the factory been involved in any of these replacements? Are the gears ok? Where are the shafts failing? At the same spot? Do they twist and bend or just crack apart? Could you post a closeup picture of the broken pieces?

 

[Javinka]

It's pretty consistent in the same spot, give or take an eighth of an inch or so. We've had a warranty repair on it the first time, but the dealer felt he was actually just doing us a favor. As far as he was concerned , it had to be operator related.

 

[bucktaker]

have you checked your mowers to see if the slip clutch or shear is operating correctly?

 

[Javinka]

Here's a few more pics. The inside gears look okay. One shaft looks like it was twisted before it broke, but the other three are clean breaks.
That's as close up as I could get with this camera.

 

[Javinka]

Thanks, Bucktaker, that was just brought up to me, as well. I think my mechanic may be part of the problem. I am pulling my freaking hair out for poor maintenance? That would not be good.......:confused2:

 

[moored4]

Here's a few more pics. The inside gears look okay. One shaft looks like it was twisted before it broke, but the other three are clean breaks.
That's as close up as I could get with this camera.

Pictures 1,2,and 4 look like impact breaks to me. caused by impacting an object or start up torque! or so I think with pictures. Have you taken them to a drive line shop or someone that see's alot of these and get their ideals!

 

[equipman]

We have a Professional Mowing customer with numerous Kubotas and we saw this happen once on a M120 pulling a 20' mower. It happened after almost 5000 hrs and we figured it was just fatigue. Since you have had several occurances, I would really look at the slip clutches on the mowers first. A combination of ground strikes and non functioning slip clutches could certainly cause the PTO shaft to break.

 

[blueriver]

All good advise. I'm leaning to the operator's engaging the pto at full pto rpm. A sudden force at high rpm's.