Tractor Driven PTO Generator – Read Before You Use One

A tractor powered PTO driven generator is one of the most sensible purchases that almost any farmer could make. Apart from powering those once a year electric loads like grain dryers or bin fans, they can also be convenient and relatively inexpensive insurance against those all too often power outages that occur in rural areas.


A PTO driven generator can easily last for 10000 to 15000 hours without any maintenance at all. For most users, that’s more than a lifetime of usage. The owner should mark the hours of the tractor somewhere on the generator when it is new to keep track as at around 12000 hrs, the generator bearing should be replaced. The bearing is located in the rear of the generator and should be replaced by a motor rewind shop. The cost shouldn’t be more than a few hundred dollars unless the bearing has worn the housing and machining is required. Also, don’t let them “up sell” you to have the generator cleaned. It doesn’t make any trailer insurance difference in operation or lifespan. I have had many generators in my rental fleet with 60000 hrs that have only had generator bearings replaced and still going strong.


– Be certain that the generator is bolted securely to something that is stable and wide. When a large electric load is encountered, the torque on the generator will cause a twisting force.

– Place the generator so that the PTO is level. It is the most mechanically efficient that way.

– I recommend that you construct a well ventilated shelter that protects the generator from blowing snow and driving rain. Too many owners have built shelters that have no ventilation. Generators produce heat. While they do have a fan at the front of the generator for cooling, the colder the ambient temperature that they can operate at, the longer they’ll last.

– Never ever trust your tractor’s tachometer. Thanks to the folks in China, you can now go buy a decent quality multimeter at most hardware stores for under $50. Make sure that you get one that can measure both AC volts and hertz or “HZ”.

– Increase your tractor’s rpm until you reach 62hz on the generator. Normal operation is 60 hz. This setting will allow your tractor engine to lug as electric load is applied.

– Without an electric load, slow the tractor rpm gradually until you notice the output voltage starting to drop from its normal level. This should occur between 54 hz and 57 hz. Any lower than that and the excitation system of the generator can be damaged if the rpm of the PTO slows for an extended amount of time. This situation can easily happen with a clogged fuel or air filter. The setting is usually done correctly in the factory, but I’ve seen it missed. You can find the adjustment on the voltage regulator. It will be labelled as “under frequency roll off”, “UFRO”, or something similar.

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