***"sometimes when trying to reengage the PTO or engage the transmission it will kill the engine"***
Sounds like it may be related to a safety interlock switch, or a relay that is part of the safety interlock circuitry. Is your PTO hydraulic, controlled by a solenoid valve? If that is the case, a defective solenoid valve might be overheating to the point of "going open" or even "shorting out" after it has been energized for the 20 to 30 minutes of operation. But, sometimes relays can act up when they are overloaded by too much current draw when they get old, or, if the device they are controlling develops too much resistance or "shorts out". When the engine "kills", will the engine crank right back up? or does it act like the battery is weak or dead?

I always try the easy stuff first, such as "won't start" - check for gasoline. In this case, I'd charge the battery. My old Econo will die when I engage the PTO if the battery is low - seems there's enough juice to start & run the engine, but not to also activate the PTO.

I am having a similar problem with my JD 445. Here is my troubleshooting so far.
The 445 has two PTO, one for the mower (front) and the tiller or other (rear) attachments. I tilled with no problems last night and went for a good 30 mins. The day before, I was cutting the grass and the PTO was shutting itself off a few times (similar to your problem). Today, I tried cutting again and only went for about 10 minutes.

The PTO in the mower position stalls the engine when I engage the PTO, where as the rear PTO works fine. Since one works and not the other, I don't think it is the safety switch.
I changed the solenoid last year (when I had a faulty PTO switch).
When I engage the mid PTO, the engine starts to stall, but if I un-engage the PTO, the engine has not problems revving up again.

I would wonder how the electrical system could manage to crank the engine (huge current draw) and then not manage to have enough oomph to operate the solenoid for the PTO and the fuel solenoid to to feed diesel fuel to the fuel pump. Both the fuel solenoid and the PTO solenoid together do not come close to the current draw of the starter when cranking a diesel engine. Perhaps hansue will visit again and post new information.

Try weekendfreedommachines.org for some good info. Those symptoms are kind of odd, so I echo that you should revisit the chain of events and get back to us. Good luck!

FYI, the PTO is an electric clutch (not hydraulic) and there are several safety interlocks that tie into the TDC (time delay control) module. Don't get too scared, it's easy to diagnose.

Guys, my 445 is fixed, temporarily. It was an electrical problem for me, this time with the seat safety switch.
Right now, I'm running a relay to make the tractor think the switch is on until I order a new part from JD.

Thanks for the help. Good luck with yours Hank.

PTO engages mower when cold, will not re-engage after 30 min. opperating. Mower works well continuously if you do not dissengage the PTO. Have had a suggestion that PTO Clutch needs replacing. Any ideas and is this a simple thing to replace, that is , can I a home mechanic do this ?
Regards Max.

Further to my ';John Deere PTO problem' email earlier today..... I have read on a US site that my PTO problems might be simply solved by tightening the 3 locking nuts, 9/16 size that appear to hold the clutch to the motor...... any ideas please before I try too many cures.
Regards Max.

I am working on a JD 322, with a Yanmar Diesel Engine Co. 3 cylinder GAS engine for a guy. How does the Time Delay Control Module interact with the safety switches ? Also, somebody mentioned an engine stallout when engageing the PTO switch. Is the throttle set at too low a speed when this happens ? Just a thought. Scott.