Using a JD 245 Lawn Mower to run a Generator?

[FarmDiesel]

We've been having a lot of power outages, and I've been thinking about getting a generator. However, the thought of having another small gas engine to maintain doesn't excite me. So I was thinking about it a bit, and I looked at my trusty JD 245...and got to wondering if I couldn't buy a generator head, put a pulley on it, and make an easy to install/remove bracket to hang it off the front of the mower. Power goes out, slap the generator head on the front of the mower, unhook the mower's belt, stick a belt between the mower drive pulley and the generator head, and crank it up. The issues I see so far are:
1. Determining the speed of the mower drive pulley, so as to be able to determine the appropriate size pulley for the generator head.
2. The tension from the belt on the generator will pull the mower drive pulley forward, compared to it being pulled aft by the mower drive belt. Any problems there?
3. Will the mower drive clutch take the constant load from a generator?
4. How big of a generator head can I use? 10KW?
5. Any problems with the electrical system on the tractor if a 110v generator is hanging off the front of it?
6. What am I not thinking of?

Anyone do this before?

 

[Dutch445]

It'd be much easier to run off a 540 pto , do you
still have any tractors with that?

I think it's going to be very hard to adapt from the mower pto, which is at engine speed... to a generator.

as far as size, 10kw is probably the biggest to consider,
but with that tractor i'd doubt you could get more than 6,500 or 7,000 watts from it.. i don't know really, i'm not sure if it's been done before!

/forums/images/graemlins/cool.gif

 

[FarmDiesel]

Well, the problem is one of logistics.

We have one farm 30 miles east of my home with a bunch of older gassers that have 540 PTOs... an H, a 560, a 656...and an older Winpower generator in there to run cribs and such that don't have electrical service anymore.

At my folk's house, about 10 miles south of my home, they bought a standalone generator.

At my brother's house (the home farm), about 5 miles to the east, we have a few more tractors with a 540 PTO (a Super M, a diesel 685, and I think the 7230 has 540 and 1000 rpm PTOs). The downside to getting another generator for them is that I'd have to run over to the home farm, grab a tractor, drive it back to my place, etc. And I'm in a slightly more residential area (small, rural town), where a tractor running at PTO speed to spin my generator would attract far more attention than just a little lawnmower churning away.

That leaves the question: how do I determine the RPMs on the pulley...

I think the engine is a 15hp model. I think that'd be enough for probably an 8kw generator.

Maybe now's the time to convince the wife to get a CUT and a PTO generator...Naw, that probably won't work.

 

[Dutch445]

oh, you are talking about the older 245, not a newer GT245,, sorry, big difference. I was thinking you had 20hp there.

I think most engines like that run about 3400 or so rpm at WOT, and 14 or 15 hp, it sounds even harder to do what you want.

I can't help you any more, I've never seen anything done like this to date.. maybe somebody else can intervene with other ideas...
you'd have to drive some sort of gearbox from the electric pto on the crankshaft.. sounds very complicated to me!

good luck!
/forums/images/graemlins/cool.gif

 

[pennwalk]

I have an old Homelite generator in the garage. It looks like 5 hp and puts out 2.2 KW. The generator runs straight off the motor at 3600 rpm. I saw a old red generator head that attaches to the front of a l&g tractor at the JD dealer so some red brand did it in the past. It ran off a belt. My Yanmar 186D has an electric pto on the front of the engine. Duel v-belts turn a 540 gearbox to run front attachments. I think the JD X tractors have a generator attachment but I think it runs off 540. What is the name of that surplus outfit that has the great catalog? They used to have all kinds of neat stuff for a project like this.

Chris

 

[pennwalk]

<font color="blue"> What is the name of that surplus outfit that has the great catalog? </font>
It came to me /forums/images/graemlins/grin.gif Surplus center
Their catalog makes great bathroom reading. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Chris

 

[FarmDiesel]

After further research, this doesn't look like too difficult of a project. There are a lot of generator heads out there made to run directly off a gas engine...I just need to do some pulley calculations, get a head, and make a mounting bracket.

 

[John_Mc]

If you find a generator head that is designed to hook directly to a gas engine, you should be in the ballpark. Maybe some fine tuning to do with pully sizes.

Rough rule of thumb: you need about 2 HP on the gas engine for every 1 KW from the generator.

The biggest problem you may have is the throttle control. Setting the RPMs right to get 60Hz / 120 volts from the generator is very important. You can fry some electronics and some motors is this is not controlled. Most generators powered by a gas engine have some sort of governor to control the throttle. When a heavier load comes on and starts to slow the engine, the throttle opens up. Most mowers are not set up this way. (Set your throttle, at about 3/4 and then drive up a steep hill in a higher gear, or otherwise put a load on it. You'll hear the motor slow. It probably won't come all the way back up to "normal" until the load is taken off. Do the same to a gas generator by switching on a big load. You may hear the RPMs dip for a second, but the governor corrects it pretty quickly, up to the point where you eventually hit the max the motor will handle.) If you have a relatively constant load, you might get away with just setting the throttle for that load and leaving it, but if your load varies, you'll probably have some problems. (Diesel engines tend to have less of a problem with this than gas.)

Watch for belt slippage as well. Not sure how the torque required to drive a mower compares to that required to drive a generator, but it's possible one belt won't handle it. The more HP and KW you are looking at, the more likely this could be a problem.

I bit the bullet and bought a small (4 KW) generator to get me by in an emergency. Power is unreliable out here at the "end of the line". Didn't want to deal with keeping enough fresh gas around to run it, so I put a conversion kit on the carburetor that lets me run it on propane (we have a 500 gal buried tank) or on gas. The nice thing about propane is that it doesn't go stale or gum up your carburetor. It's still portable, since I can always fill the gas tank if needed.

John Mc

 

[Boog]

Hi Farmdiesel. Where are you in IL? I grew up in Polo, went to an Army reserve unit in Savannah and my best friend lives in Dubuque, IA. Anywhere around there? Like you said, you'd have to size the generator pulley just right for a given engine rpm to get the 60Hz you need. I have one of those "Tiny Tachs" on my GT235 and it tells the rpm pretty good. WOT is only around 3200 so "I" would have to have a smaller pulley on the generator than the PTO to get the 3600 rpm (which yields the 60HZ.) Then when the drive pulley (PTO) is turning a smaller pulley (generator) you are not getting 1 for 1 horsepower trade either; you are LOSING useable HP in that case. So that also will dictate a smaller generator. The load direction on the engine pulley will not matter. To the drive clutch, the generator will look just like a continuous swath through grass with the deck on it (higher grass is like more amp draw on generator) I don't see how the generator will have any effect on the tractor electrical system - they are not tied together. Unless you are thinking of electical or magnetic fields around the generator; at only 110V nothing will escape the generator casing. It is those big power lines at 1000s of volts and no significant shielding where this is a problem.

 

[CubSpaceCadet50]

Very interesting discussion and a perennial topic. I'm thinking of doing this myself with my new Cub Cadet GT 2550. It has 21 HP and the first / largest generator head I looked at gives about 7KW, as was guessed above. The generator head is at Northern Tools and is the same as their 10KW unit for use with a proper PTO.

Since first reading this discussion, I went to the Kohler engine web site and downloaded the service manual for my engine. If the standard governor is not sufficient to keep the generator at 3600 rpm under load, they also have an electronic governor, which I assume is more accurate. I know a little about that - PID controller class was when I decided I would never be a working EE! /forums/images/graemlins/cool.gif The manual also mentions a gaseous (natural or propane, the latter I have) version of the engine.

That leaves me with 3 questions: 1) Where's a good source of pulleys? 2) Got any tips on design and who can fabricate this? I was thinking of a bracket for the gen-head that hangs off the front of the tractor. I would need a good way to tension the belt too - about this I know nearly nothing! /forums/images/graemlins/grin.gif 3) Lastly, has anybody found and/or tried the LP gas conversion? That would be a longer term project. I manage pretty well without power, except for a septic pump, so I only really need a little power every so often. Found my power requirements out in the ice storm of 1998 here in Vermont.

Thanks for any help.