Posted 8/31/2024 11:24 (#10873547) Subject: Twisting off the 1000 pto shaft on 7120 CIH tractor.
West Central Indiana
I have a 7120 with 8000 hours. It's been our 15' bush hog tractor since my dad bought it used in 1998 with about 2200 hours on it. It has done other things on the farm since then...but I'd bet most the hours are on the mower.
Two years ago a young guy was mowing for me and brought the tractor in with the 1000 shaft sheared off clean at the back of the tractor. It was leaking a little oil out around the seal. I had the dealer come out and install a new shaft and rebuild the pto clutch. I didn't think much about the twisted shaft...just figured it had fatigued from all the years of mowing. Yesterday a different guy (long time employee) that works for me said he engaged the pto lever and the shaft snapped off clean on the back of the tractor just like 2 years ago.
My question is do I need to sit them both down and go over how or how not to engage the pto? Is there a hydraulic setting to adjust how hard the pto comes on? Are these tractors prone to this issue? I bought a different mower 3 years ago. Could it be something with the mower causing the issue?
I got along great with this tractor/mower combo for so long. Seems odd to have 2 shafts broke within 2 years.
Posted 8/31/2024 11:32 (#10873555 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
McCanna, ND
Twisted/locked up pto shaft sheared the big 1 3/4” 1000 off our 4wd. I was slightly impressed a hollow tube could exert that much force without bending itself.
Posted 8/31/2024 11:51 (#10873570 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
mercer county, il
Does it have a cv joint on the front? Is said cv joint tight?
CV joints are a lot of weight hanging on there, and if they get a little bit of wear, that’s a lot of weight that’s trying to pull that pto off axis. If the shaft was actually twisted, I’d look at the operator as well as the metallurgy of the shaft. If it’s a clean granular looking break, I’d be looking at the cv shaft. That much weight at speed can quickly take a hard steel (brittle) beyond the kind of repetitive flexing it can handle.
Posted 8/31/2024 12:01 (#10873584 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Ohio
I broke my 8920 PTO just like yours. It ruined the seals, bearings and cast housing too. He'd to but a rebuilt PTO from France, only one available. $16,000 later, I'm afraid to use the PTO now
Posted 8/31/2024 17:10 (#10873867 - in reply to #10873584) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Callao Missouri
tj_farms - 8/31/2024 11:01
I broke my 8920 PTO just like yours. It ruined the seals, bearings and cast housing too. He'd to but a rebuilt PTO from France, only one available. $16,000 later, I'm afraid to use the PTO now
Posted 8/31/2024 12:36 (#10873617 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
The Internet
A place I worked once had a John Deere 3040 that snapped the PTO internally. There must have been a flaw in it, because it didn't have the grunt to snap a carrot in two.
Posted 8/31/2024 18:56 (#10873929 - in reply to #10873653) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Clarksville, IL
tore out 8930 one up oh man been 15 years now if not 20, had to go to dealer to get split ruined stuff inside, guy came out said cv joint was gone on chopper, was only 2 years old, first one lasted 10 years, was told every 3 years replace no questions
Posted 8/31/2024 13:24 (#10873665 - in reply to #10873617) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Faunsdale, AL
4320 here…….drawbar broke, pto shaft pulled out, flailed around and locked against 3 point arms….. Hollow shaft inside snapped. Never seen a JD stub shaft snap off……..yet……..
Posted 8/31/2024 15:35 (#10873797 - in reply to #10873665) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
just a tish NE of central ND
ccjersey - 8/31/2024 12:24
4320 here…….drawbar broke, pto shaft pulled out, flailed around and locked against 3 point arms….. Hollow shaft inside snapped. Never seen a JD stub shaft snap off……..yet……..
I could have shown you a bent one. Same deal. Lost a pull type combine on a 4320 and the pto separated and the stub shaft got bent out of round.
Posted 8/31/2024 20:46 (#10874041 - in reply to #10873617) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Ludington/Manistee MI area
The Pretender - 8/31/2024 13:36 A place I worked once had a John Deere 3040 that snapped the PTO internally. There must have been a flaw in it, because it didn't have the grunt to snap a carrot in two.
Jockey in western Wisconsin sold me a tractor with the PTO shaft broken internally in 2 places. He has a salvage yard also and wouldn’t even help me on parts. I think he knew it and didn’t care.
Posted 8/31/2024 14:01 (#10873707 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
IL
If it isn't pretty straight when you kick them in at mid to high rpm they will snap pretty easy. Neighbors teenage kid found that out and keeps doing it so that he doesn't have to mow.
Posted 9/1/2024 09:36 (#10874510 - in reply to #10873808) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
ND
Change yoke & get a tractor with a 1 3/4 pto. 12r 30 Loftness chopper, started with a Case 2590 with an 1 3/8 1000 pto & snapped tractor shaft upon start up, replaced shaft & when chopping again later when the chopper was running snapped again, hence switched to a 4650 Deere has 1 3/4 PTO.
Posted 8/31/2024 21:14 (#10874083 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
Cullom, Illinois
Not familiar with your tractor but could the pto brake be stopping the shaft too fast? Then the momentum of the mower is snapping it off. Perhaps they were shutting the pto off at full throttle and the pto brake stopped things instantly or at least tried too. Just a guess.
Posted 8/31/2024 21:44 (#10874119 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
What kind of hp is the tractor outputting? I know that
540 is good for about 125hp,
1 3/8 1000rpm is about 200 hp
1 3/4 1000rpm is about 400 hp
2 1/4 1300rpm is about 800 hp
You can swich to the large 1000 pto on the tractor you will loose the 540 rpm if you do this.
Posted 9/1/2024 00:07 (#10874218 - in reply to #10873547) Subject: RE: Twisting off the 1000 pto shaft on 7120 CIH tractor.
NCMO
You might want to take a hard look at your bush hog cv joint, if it feels “sloppy “ it will break your tractor pto shaft. Last year 4430 deere snapped, our local welding shop has aftermarket cv joints at a fraction of bush hog, so far so good.
Twisting off the 1000 pto shaft on 7120 CIH tractor.
