300 U Independent PTO noise

[56Utility]

Hi,
I was mowing with my 300 Utility when somehow the drawbar pin fell out and caused the brushhog driveshaft to separate into two pieces. The tractor was at full throttle with the independent pto engaged at the time so it took a little time for everything to stop moving. Now the pto makes a knocking sound if I try to move the handle to the off position. With the pto in the on position there is no knock sound. I read on some other posts that there are more gears engaged/turning when the pto is off than when it is on. The problem is with whatever is still turning when the pto is off. My tractor does have the seasonal disconnect. I am trying to locate the source of the knock. The sound is not there if I move the lever to disconnect the seasonal coupling. Does that mean that the problem is in the independent pto housing itself? Or could it be the drive/driven pto gears in front of the transmission? Should I start by draining the transmission fluid and take off the covers underneath?
This tractor also has a TA if that makes a difference. I am hoping I can fix this without splitting the tractor.

 

[Janicholson]

The fact that the noise stops when the seasonal disconnect is off is a good sign, but not definitive. The fact that the knock is gone when it is on is very positive and helps eliminate the PTO front drive gears. Gears with zero load often are quiet, so there could be damage up front, but less likely. There is nothing to be gained by splitting. Here is a diagnostic. With the seasonal disconnect cover removed you will see the shafts and a coupling for On Off. With the coupling not driving, turn the PTO shaft going to the rear with a groove joint pliers, or other tool so it can be rotated with the PTO main control lever in the off position where it knocks. Feel the tool used to turn the shaft carefully to assess a change in motion, or different feel if the knock (or stutter in rotation) is felt, the damage is in the PTO. It is easily removed from the rear housing, and (though heavy) will come out with no further disassembly. The draining of rear end oil is a good idea in that the level is higher than the opening. Do not pry it away from the housing, IIRC there is a long bolt that is necessary to remove at the top. There ar complex gears and planetary carriers in the assembly, take images as you go. Good luck. Jim

 

[used red MN]

I will say I am pretty sure this is how this operates.The IPTO engages by a brake band clamping on a drum that is connected to the planetary carrier of a planetary gear set. So when disengaged this planetary gear set is still in motion but turning the opposite direction. A second band brake stops and holds the PTO output shaft from turning. For some reason the band brake can apply side pressure on the gear train. This tends to amplify noises produced by the running planetary gear set that is not under load. Some noises like a whine and knocking as the engine runs uneven is normal. If the noise you are hearing is new and unusual it is probably best to remove the unit and check it over. I am attaching a link to the CNHI IPTO parts diagram for your tractor. If you are viewing this on a phone you need to click the picture icon at the bottom to see the diagram.
Diagram here

 

[Janicholson]

Jim's modification to your description: The IPTO engages by a brake band clamping on a drum that is connected to the ring gear Part 8 of a planetary gear set. The carrier is attached to the output shaft, so when the ring gear is locked, the sun drives the planet carrier in the same direction, but reduced speed. When disengaged this planetary ring gear set is still in motion but turning the opposite direction (no forced turning of carrier, neutral). A second band brake stops and holds the PTO output shaft from turning by stopping the carrier. this breaks the output shaft to a halt, and forces the ring gear to rotate in the opposite direction. The running planetary gears when not under load are running faster than when engaged. Best I have, no flame the ideas are complex. Jim