Mowing Kubota PTO Breaking

[Javinka]

Thanks, all of you. Great points for me to think about! I hope you all have a Great Holiday Season!!!!!!

 

[slowzuki]

1. Check your slip clutches
2. Check your pto length with the tractor parked on the uphill of a dip and the mower on the down hill. Make sure the shaft isn't bottoming out, it will push the output shaft down and break it.

 

[rbargeron]

Those breaks have a little of everything - combined side load, twist, and brittle fracture. The spiral break is more of a torsional failure - but the first pic is a classic brittle failure. Slowzuki's idea about the shaft pushing down with a bending load rings true to me. If it was all due to torque impact some gear tooth damage would be expected too.

Dumping the clutch to spin up a big mower from stopped can overload the driveline to the breaking point for the shear bolts. Check that the shear bolts in the drive line haven't been replaced with hard (grade 8) bolts. Hard bolts transfer the abuse to a more expensive part.

I'd ask the dealer to show those parts to the Kubota service rep and get some factory eyes on them. To my semi-trained eye they look through-hardened near the bearing and maybe case hardening with a ductile center would be better for this part.

 

[Grateful11]

How well do you know and trust your operators? I've seen operators break stuff just to get down time, I'm not saying that this is happening but I know that in the field I used to work in that was done by operators and then we would have to fix the stuff. I've seen 6" axles snapped off and we had to scratch heads trying to figure out how and why. This was on rail maintenance equipment.

 

[andrehoude]

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.

I think it's the drivers that are rough on you equipment

 

[Tx Jim]

I agree with the other posters that think it's slip clutch related(stuck from rust or too tight).

 

[Deere9986]

last yr we ran 3 9540s and 3 m100xs and broke 2 or 3 shafts on the 100s and not a 1 on the 9540s. this yr we went to deere 3 5093es and 3 5101es and have broke 3 shafts in them. funny thing is the only ones that break them are the ones that have 4 clutches on the mower slip clutches. we run 1 rhino sr15 with 4 clutches, 2 landpride 5615 with 4 clutches, and 3 bushog 2615l that have 2 clutches per slip clutch and the bushogs never broke the pto. plus its not always the driver, i broke one with 50 hours on the m100x and new mower just by turning it on at idle.

 

[grsthegreat]

I second the vote for checking the clutch and or too strong of shear pin. Man, that break looks painful. id me crying :mur:

 

[kuboman]

Check the slip clutches and pto length.:thumbsup:

 

[MHarryE]

Some look like torsional overload but at least one appears to be bending fatigue. Is it possible you have one mower with a bent drive shaft? We had one of our old IH 1456s snap its 540 rpm PTO shaft this year running a chopper and discovered a bent PTO driveline was creating a wobble that fatigued the shaft. The failure looked just like your picture of the tractor end.