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Discussion Starter #1
I recently had to change out the engine (3TN84-RJ) on my tractor, threw a rod. That is not my problem now. When I engage the pto (either mid or rear) the pto will function for a while then just stop. However, the light stays lit indicating the pto is still engaged. With my 72" mmm it runs fine for a while then out she goes. I immediately reset the pto handle and she is off running again. No slippage. The same is true for the rear, I have a pto pump for spraying. The same happens. It seems, as the tractor heats up, the problem goes away. I have checked the wiring from the seat and over-rode it, still disengages. There are two sensors on the rear and side of the transmission casing that appear to be either pressure or temperature. They are a continuation from the seat switch. I don't know what their function. Every thing I read is that the 955 has a wet multi-disk pto clutch. Could it be slipping or having other problems. any advise will be helpful. Thanks George
 

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My first thought and question is, do you have the proper amount and type of hydraulic fluid in it?
 

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My first thought is the interlock magnet is getting weak and dropping the PTO engage linkage. When you pull the PTO lever back it picks up the linkage again and re-engages the PTO.
 

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Discussion Starter #5
Thanks for the advise. I drained the hydraulic fluid, cleaned the filter screen and changed the filter. New fluid for transmission. The pto does not drop out as if you attempt to get off the seat when operation. That makes me believe that the magnet is holding fine. I don't have the service manual but by reading on other models with hydrostatic transmission it appears there is a solenoid on the transmission that pulls in the pto clutch I'm going to try to locate it and check it electrically.
 

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No solenoid that I'm aware of. Unlike the newer models, the 955 was a "mechanical" tractor... meaning that virtually everything was controlled by a mechanical linkage instead of switches, wires, and solenoids.
 

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Discussion Starter #7
Thanks again. Well, I went out and put the mmm back on this morning and mowed about an hour without the pto dropping out. Must be gremlins. Because, when I washed her down I noticed the front wheel bearing seal was leaking. Got it tore down and waiting for parts from local John Deere dealer. Always something.
 

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Perhaps it is/was a loose or bad connection in the wiring harness causing an intermitant contact in the PTO magnet circuit???

The two switches (one on the left side and one on the rear of the transaxle) don't factor into weather or not the PTO engages during mowing. One of the switch is just a switch for the PTO lamp on the dash. The other switch is only used during the seat safety switch override function for using the rear PTO without an operator in the seat. The only factors in the PTO magnet circuit are the seat switch and the Time Delay Module.
 
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