PTO Generator conversion

Dave from Texas · Dec 28, 2017

Looking at the Post below, I have always wondered can you convert a engine driven generator to a PTO driven? I think the engines turn 3600 RPM which means I would need to increase the PTO (540) by 7 times. Has anyone done this? The engine is to hard to start with a pull rope.

hydro70guy · Dec 28, 2017

Easy enough to do PTO drives a smaller pulley with bigger pulley being the driven pulley. Might be easier to look for a used PTO driven generator already setup. I helped make a big generator for a town run off PTO to run there water tower and other infrastructure years ago using the pto and flywheel off of an old grinder mixer it worked well.

Joe

fastfarmall · Dec 28, 2017

I was going to say also, buy a old Bear cat grinder, they got a belt setup about 8 inches wide,the big one drives the small one,[i think] that should give you plenty of RPM, nice big pillow block beargings.

BarnyardEngineering · Dec 28, 2017

Most engine-driven generators are set up with a socket that the crankshaft of the engine fits in to drive the generator directly. It is usually tapered, not straight. So, there is nothing to put a pulley on to drive the generator.

Even if you made up a stub shaft and found a way to keep it in the generator head, the bearings in the generator were not designed to handle the side load from a V-belt pulling on them.

Also getting from 540 to 3600 RPMs would be best done with two steps up. Otherwise the drive pulley would be excessively large (i.e. 21") and the driven pulley would be excessively small (i.e. 3", which is pretty tight and would burn out belts quickly).

All of that can be overcome but it makes things more complicated than they necessarily need to be.

Ideally you would want to find a generator head that was originally belt-driven for best results.

JDEM · Dec 28, 2017

My Generac 15KW PTO generator has a 7 to 1 step-up gear box that has to handle over 30 horsepower. Seems you'd need to find something similar. Cannot think of anything that would be cost efficient. An entire good-working PTO generator can be had for $500-$600.

John T · Dec 28, 2017

Sure a gearbox conversion can do the trick if it has sufficient rating but they are EXPENSIVE. A belt driven step up can work and may not be as expensive but you don't find such items readily on store shelves. You may want to look at the economics and practicality of your idea but I'm all for rigging things myself SO GO FOR IT

John T

Duane WI · Dec 28, 2017

I don't know if it matters but a PTO turns in reverse rotation compared to the engine. A gear box would change the direction back to the same as the engine. A belt drive would not change the rotation direction. I don't know if the generator cares which direction it turns or not.

David G · Dec 28, 2017

Just curious, what is KW of the generator?

BarnyardEngineering · Dec 29, 2017

All you have to do is turn the generator end-for-end to get the correct rotation.

If the generator would be turning backwards with the input shaft facing forward, turn it so the input shaft faces the rear.

PTO Generator conversion

Dave from Texas

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hydro70guy

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fastfarmall

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BarnyardEngineering

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JDEM

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John T

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Duane WI

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David G

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BarnyardEngineering

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