</font><font color="blue" class="small">( How far would a PT have to be towed or rolled to produce damage and what kind of damage would result.
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I think it's probably a matter of YMMV (your mileage may vary). The particular problem is that if you push/pull the tractor without opening the tow valve then you are forcing hydraulic fluid through the system. So you are looking at damaging both the pump and the motors, but probably primarily the pump.
Disclaimer: I don't know for sure, I'm just theorizing.
Fourteen: You do have a point with your last point about "What ifs" but then one could also ask why bother carrying a fire extinguisher strapped to the ROPS of your PT? Surely, the possibility of fire is as small as a piece of junk clogging the fuel filter which stalls the engine which sends you on your way down that hill.
Aside: I had a conversation with someone on the weekend related to brakes and tractors. He said that even large tractors have poor brakes and that runaway tractors are not uncommon. Clearly, most of this equipment is only designed for relatively flat land. That's puzzling.