PTO slip clutch adjustment - burning up discs

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
The PTO shaft on my Land Pride RCF3696 rotary cutter is burning up discs. This PTO shaft uses the Comer 2 disc clutch.

The first replacement set burned up pretty quickly. I installed them and set the spring snug, then turned each one 2 full turns. I measured each spring with a caliper and adjust to get them all the same depth. So yeah that was frustrating. I had them adjusted to the same depth as the OEM setup.

The second set, installed this morning, also burned up. I did get a lot more use out of them, but nowhere near what they should deliver. I thought the heat from the first and second set of discs burning might have glazed the surfaces. When I had it disassembled I worked each mating surface over with my angle grinder with a flap-style sanding disc. I was pretty satisfied that the surfaces are now in good condition.

I snugged the springs, then turned each one down 3 1/4 turns. Measured with a caliper, adjusted. I was very conscientious about the deck height while I was working, but I did have some rough stuff I needed to cut down in my pasture. I worked about 6 acres and the shaft burned the discs and was spinning freely.

I just don’t understand what is happening. My tractor is a M5-111 and the original set of discs lasted 2+ years. In a week I have burned through 2 sets of replacement discs. I bought the discs from the parts counter at my dealer, the part numbers coming right out of the parts computer. Could my springs and nuts be damaged from the heat?
 
Last edited:

mcfarmall

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Equipment
Kubota M5660SUHD, Farmall C
Sep 11, 2013
1,411
1,691
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Kalamazoo, MI
Sounds to me like the spring pressure is way too low. Might try cranking those bolts down a lot.
 
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altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
Sounds to me like the spring pressure is way too low. Might try cranking those bolts down a lot.
That is what I thought. The extra 1 1/4 turns today bottomed out the springs. I ordered some new discs, maybe take it up to 4 full turns past snug. I will resurface the faces just to cover my bases.
 

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
Does your dealer (mower manual) have a torque for those bolts? Think I'd start there.
The manuals are all online. But the bolts have tensioning springs, which makes torque irrelevant. Measuring the spring height is the way you are supposed to do it, after establishing enough friction to hold the pack toagether but allow for slip. I seem to be in the scenario where I cannot hold friction.
 

Smokeydog

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Equipment
M59, B26 grapples, backhoes, tillers, graders, diesel atv
Jun 2, 2020
681
638
93
knoxville, Tennessee
Should be checking slippage during use and tightening as required. Different colored paint pens help monitor adjustment. Shouldn’t be slipping under normal use. Of the five implements I have with slip clutches have never burnt up or needed to replace the clutch plates.
 
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GrizBota

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Equipment
L3830HST/LA724, B2601/LA435/RCK54-32, RCR1872, CDI 66”grapple, pallet forks
Apr 26, 2023
1,153
736
113
Oregon
Swap out the PTO shaft for one with a shear bolt?

Ate you sure the metal discs are in good shape? You mentioned surfacing them with a flap disk on an angle grinder. Those can remove material in a hurry. Just used one to clean out cracked welds and smooth the new welds on my RC1860.
 

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
pretty sure… I ran the disc over the faces to clean them up, light pressure and moved quickly.

I’m going to rebuild the clutch, set the springs to 2 turns beyond snug, then run the PTO on/off a couple of cycles to bed them in. I’m also going to put the PTO in eco mode to get to 540 at lower engine RPM. Adjust the spring tension using the pen method referenced in one of the replies here. Then make passes at lower speed, see how it goes.

I am getting to the point where I just want to replace the entire PTO shaft, but it is worth problem solving to build knowledge for the future.
 

Runs With Scissors

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Equipment
L2501 TLB , Grappel, Brush Hog, Box Blade, Ballast box, Forks, Tiller, PH digger
Jan 25, 2023
2,517
2,922
113
Michigan
Just a SWAG here, but are the blades spinning as freely as they should?

Maybe some sort of "extra" resistance is putting a 'larger than normal' load on the system hence when you are cutting, it is overwhelming the clutch's?
 

BAP

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Lifetime Member

Equipment
2012 Kubota 2920, 60MMM, FEL, BH65 48" Bush Hog, 60"Backblade, B2782B Snowblower
Dec 31, 2012
2,785
896
113
New Hampshire
Good possibility that 1 or more of the steel parts is now warped causing the clutch to not seat properly and burn itself up. Also, looking at the owners manual, it lists 3 different spring length adjustments for your mower depending upon which slip clutch your machine has. Have you verified which one you have so you can use the correct specs,
 

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
Just a SWAG here, but are the blades spinning as freely as they should?

Maybe some sort of "extra" resistance is putting a 'larger than normal' load on the system hence when you are cutting, it is overwhelming the clutch's?
good suggestion. I did reach under the deck and test for any obstructions. I can spin the gear box smoothly.
 

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
Good possibility that 1 or more of the steel parts is now warped causing the clutch to not seat properly and burn itself up. Also, looking at the owners manual, it lists 3 different spring length adjustments for your mower depending upon which slip clutch your machine has. Have you verified which one you have so you can use the correct specs,
Yeah, it is really frustrating that Land Pride uses so many PTO setups on this attachment. They really use just two, but in each case there are obsoleted parts. I did narrow down my specific PTO and spring height spec.

I did run a machine straight edge over the clutch faces and each one checked out. I am increasingly of the mindset that I need to order new springs.
 

altamontfarms

New member

Equipment
M5-111
Jan 23, 2021
17
8
3
Fort Myers, FL
Yeah, it is really frustrating that Land Pride uses so many PTO setups on this attachment. They really use just two, but in each case there are obsoleted parts. I did narrow down my specific PTO and spring height spec.

I did run a machine straight edge over the clutch faces and each one checked out. I am increasingly of the mindset that I need to order new springs.
I rebuilt the clutch for the 4th time. I bought new springs and for good measure I also replaced the bolts. No issues now.
 
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