Flail Mower breaking PTO: over running or over power?

[mackerevich]

I was doing light flail Mowing with a 7' Rears Flail with heavy knives and a 140hp CI 7110. One day a PTO ujoint broke and the next day the PTO sub twisted off the tractor! both times, the mower was on the ground and running. The direction of the twist indiocates the mower stopped and the tractor twisted it off in a clockwise direction, not counterclocwise which would indicate over running. I afraid to try it again. Any ideas what's going on? Would a PTO adapter prevent this?

 

[jlsmith]

Do you have a slip clutch on the mower?

 

[mackerevich]

the mower is belt driven so it has no clutch. At first the belt was squeeling, so I tightened it. Thats when things broke. The factory rep did not think it broke because it was too tight, though. The perplexing thing is I was mowing very thin, dead grass. I usually have no problem mowing heavy sudan with the knives in the dirt. You can turn the rotor with one finger, so the bearings are good. The difference is I was using the big old tractor. The pto has not been used on that rig in years.

 

[aczlan]

the mower is belt driven so it has no clutch. At first the belt was squeeling, so I tightened it. Thats when things broke. The factory rep did not think it broke because it was too tight, though. The perplexing thing is I was mowing very thin, dead grass. I usually have no problem mowing heavy sudan with the knives in the dirt. You can turn the rotor with one finger, so the bearings are good. The difference is I was using the big old tractor. The pto has not been used on that rig in years.

Can you post a picture of where the shaft broke? Might have already been a crack there.

Can you turn the PTO shaft (on the mower) by hand when it is hooked to the 3 point now?

Aaron Z

 

[greg_g]

Is it the original equipment PTO drive shaft, or an aftermarket replacement? I ask, because I rebuilt a 74" flail which was missing the PTO shaft when purchased. I asked a mail order company for the appropriate shaft, and installed what they sent me. My 45hp tractor put a twist into the shaft within minutes. Had a helluva time getting it off. They considered it defective, and sent me a replacement. Took about 1.5 seconds to snap the replacement in two. Turns out they spec'd the wrong shaft from the git-go. 3rd time was the charm, finally got the right shaft. It was clearly a much more heavy duty unit, weight probably 3 times as much as the first two (quite a bit more expensive too). Have several dozen hours on it now, no problems at all.

//greg//

 

[Soundguy]

wow.. did i read that right? a belt driven implement ripped the pto shaft off the tractor?

something ain't right.. I'd FOR SURE never run that implement on my tractor EVER again without a liberally adjusted slip clutch

soundguy