Gr2100 pto problem

[Baptiste881]

Hello,

I have a Kubota GR2100 with a mower blade problem. I’ve read on the forum about some cases similar to mine, but not exactly the same.

Last year, I opened the transmission to replace the broken input shaft bearing. I took the opportunity to upgrade the transmission using the kit offered by Kubota. I replaced the wheel clutch discs and a few PTO discs that were out of spec.

Everything was working fine until last week. I was mowing, and when the grass catcher became full, I went to empty it. But when I tried to engage the blades again, nothing happened. With the lever engaged, the blades do not spin.

My oil level is fine. When I remove the driveshaft and engage the blades, the shaft spins. I tried turning the shaft by hand with the blades disengaged, and it turns with some resistance. With the handle halfway engaged, it turns freely, and with the handle fully engaged, it becomes hard to turn the shaft. The easiest way is to rotate the whole system by turning the blades by hand.

I tried adjusting the PTO lever, but it didn’t change anything. The engine RPM doesn’t drop at all when I engage the blades, as if the engine isn’t under any additional load.

Up until now, the mower had been working perfectly.

At first, I thought it might be the PTO discs, but the fact that it happened suddenly makes me doubt it. Worn discs would normally degrade gradually, and I would have noticed a loss in cutting performance.

Thank you very much for your replies.

 

[Bee-Positive]

My oil level is fine.

I assume you mean hydraulic oil not engine oil.
When's the last time you checked or replaced the mower deck gear case oil? With the PTO disconnected from the tractor but still connected to the mower deck can you turn the PTO shaft (and blades) freely?

 

[Baptiste881]

Yes, you’re right, it’s the hydraulic oil.
The mower deck gearbox oil was changed several years ago, not recently.
But I have another GR, a 2120 with 200 hours, and I tested its mower deck — it has the same problem as well.
Without the PTO shaft connected to the tractor, I can turn the blades by hand with some resistance, but they still turn on both mower decks.

 

[Bee-Positive]

I tried turning the shaft by hand with the blades disengaged, and it turns with some resistance. With the handle halfway engaged, it turns freely, and with the handle fully engaged, it becomes hard to turn the shaft.

I think what you describe is normal according to the workshop manual:

With the handle fully engaged:
The clutch lever pushes the spline boss (3) toward the rear side of the machine via the thrust collar (10), which eliminates the clearance between the clutch disc and friction plate (4), causing friction necessary to transmit driving power. So it should be difficult to turn the PTO shaft.

With the handle fully disengage:
Driving power to the PTO shaft (1) is thus shut off and brake engages to prevent the PTO shaft (1) from free-spinning. Resistance is normal.

With the handle in between the two neither of the above are true and it should freely turn.

If the PTO shaft spins with nothing hooked up but with not enough torque connected to the deck it leads me to believe the plates/disks are not engaging properly. Maybe check the clutch lever/thrust collar operation, I am at a loss otherwise. Worst case - pull it apart again.