Problem with brush hog - need advice.

[Crown & Roots Farm]

Pay attention to what parts of the PTO shaft clutch assembly are still spinning when the blade stop. I agree with K5L that it looks like PTO is spinning on input shaft to slip clutch and like others say that clutch looks rusted solid.

what holds the PTO shaft onto the input shaft of the clutch? Is there key sheared off?

this is how it connects...
just ran it with the cover off so i could see what was spinning and not spinning. the pto is definitly spinning on the input shaft. seems like if i just tighten it all up it should all spin together? would be a bear of a job though with all that rust

 

[Crown & Roots Farm]

any suggestions on how to adjust tightness on one of these? looks like the big nut on the back can be tightened but its massive and probably a bit rusted together...

 

[Midniteoyl]

any suggestions on how to adjust tightness on one of these? looks like the big nut on the back can be tightened but its massive and probably a bit rusted together...

Looks like a Sidewinder slip clutch. You can get parts for them still if you google that. Also, looks like it was discussed here before: Old FMC Sidewinder bush hog slip clutch

 

[CoyPatton]

this is how it connects...
just ran it with the cover off so i could see what was spinning and not spinning. the pto is definitly spinning on the input shaft. seems like if i just tighten it all up it should all spin together? would be a bear of a job though with all that rust

If you have the non-pictured spacing block, bolt the unit back together and run a paint line from the rear plate to the front plate (crossing 3 plates and 2 friction discs). Then run the cutter. Initially I would start at low rpm then run it up to operating (PTO 540) rpm and full shut down and check the paint lines. Looking to see in all plates and disc remained in the same place.
If everything looks ok on this test, then go mow a but until you encounter mowing issues. Then recheck for all plates and disc for slippage. This 2 stage test will determine if your slip clutch is your current issue with mowing.
Routine maintenance on a slip clutch involves slipping the clutches at least every spring before using the cutter and torquing the plates for proper tension.

 

[oldnslo]

this is how it connects...
just ran it with the cover off so i could see what was spinning and not spinning. the pto is definitly spinning on the input shaft. seems like if i just tighten it all up it should all spin together? would be a bear of a job though with all that rust

If I understand your response above the PTO shaft is spinning and the clutch is not. If is correct tightening the clutch will not make any difference. You need to figure out how the PTO shaft is supposed to connected to clutch input to prevent it from slipping on shaft and driving the clutch.

 

[CoyPatton]

If I understand your response above the PTO shaft is spinning and the clutch is not. If is correct tightening the clutch will not make any difference. You need to figure out how the PTO shaft is supposed to connected to clutch input to prevent it from slipping on shaft and driving the clutch.

There is a photo a few comments above yours that dhows the entire clutch/pro setup. If you study that photo, you can see how the pto could slip on that short shaft as the clutch slips. Proper torque could very easily correct his issue. If it does not, he needs to rebuild the slip clutch with new clutch disc.

 

[oldnslo]

Coy agree but part of the clutch should also be spinning with the PTO. Pictures do not show evidence of the clutch slipping. Like someone else posted, paint some lines across all the clutch components and go mow. This will tell you quickly if clutch is slipping vs PTO shaft spinning on clutch input.

 

[CobyRupert]

To test if clutch is rusted solid: With PTO clutch adjusted loose (ready to slip), and tractor engine off, engage tractor PTO lever. This should lock tractor PTO solid from spinning.
You should then be able to turn blade by hand and make the PTO clutch slip. Or see if driveline is slipping/spinning elsewhere.

I definitely wouldn’t operate a rotary mower that doesn’t have a PTO clutch that can slip or a shear bolt that breaks when it needs to. Otherwise, expensive parts break.

 

[CoyPatton]

Coy agree but part of the clutch should also be spinning with the PTO. Pictures do not show evidence of the clutch slipping. Like someone else posted, paint some lines across all the clutch components and go mow. This will tell you quickly if clutch is slipping vs PTO shaft spinning on clutch input.

That someone at least one of them was me!
I suspect, but the OP needs to prove me right or wrong that the center piece of metal that is bolted (4 bolts) to the PTO shaft is spin between the 2 clutch disc. If correct, torquing the large nut to correct tightness should correct his issues.

 

[Thunder chicken]

^ exactly. I have this same clutch. IF it is indeed slipping, you’ll have to tighten that big nut. May be a set screw in it as well. The ‘torque flange’ is the ‘go between’ from the clutch to the drive shaft. The shiny short part of the shaft just center’s the ‘torque flange. The clutch is splined on the gearbox input shaft so it can’t slip there unless it’s all buggered up.
hard to tell from your pics but there’s no washers between the but but and the clutch plate? Belville washers I think they are called? Kinda cupped shaped….
If the clutch does not slip when you hit something hard, that torque flange will break. They are about $100 plus a new cross bearing (35r series in my case, another $70). Expensive lesson.