How to adapt gas engine to 540 rpm's to generator??

[jburd964]

I purchased a 15kw PTO generator and have a tractor. I also have a practically new 30hp Kohler engine that I'd like to use. I'm going to go into a little bit of useless info to possibly prevent someone from making the same mistake I made. Back in 2005 I bought a Generac stand by generator. It had automatic start and would transfer power within 20 seconds of lights going out and ran on natural gas. I live in SW Louisiana and used it after hurricane Rita and a couple other occasions. It would run a self check once a week by starting and going through the motions of a actual power failure to check for problems. I did this regularly without any problems. Then in late summer of 2008 we had another storm come through and it ran for like a hour and shut down. I did all the trouble shooting I could to no avail. After weeks of trying to get a service call they showed up and charged me $150 for a thirty minute service call to tell me that the windings had came apart. The whole set up including installation was around $8000. (#&$(#*.. Saying all of that to tell you the reason the generator was reasonably priced is that they cut one major manufacturing cost. Not using copper wire, but use aluminum wire with a copper coating that expanse to much for reliable use. Hopefully this will save someone somewhere the price of my lesson. But back to my project. The generator requires a 30hp engine and that power to be transferred to 540 rpm's. I'm wondering if I could find a transfer case of some type that would have spline drive inlet and out. How could I do this as cost efficient as possible.

 

[J_J]

In order to run the PTO generator at 540, you will need to reduce the engine 3600 rpm to around 540, which will require a reduction of 6.666. You need to consider that with a load on the generator, the generator will pull down the engine rpm, and if you are already running at 3600 engine rpm, then you should only reduce the engine down with a 6:1 ratio, which will allow you to run the generator up to 600 rpm for those extra rpm's under load. There are circuits that will adjust the engine rpm to match the generator rpm's necessary to provide the correct voltage.

With the smaller reduction, you will not have to run the engine at max rpm to get correct generator voltage. The 6:1 ratio, will let the engine run at 3240 and the generator to run at 540 rpm.

Automotive axle ratios are in the range of 2.71 up to 4.31. Surplus Hydraulics has gear boxes with a 5:1 ratio, but none around 6:1. The 5:1 ratio will allow the generator to run up to 720 rpm with the engine at max, but I don't know if the generator will take that kind of rpm.

You might come across a differential to meet your needs. Other ways for reduction is with belts and pulleys, or sprocket and chain.

 

[rjmack]

what about a 4speed transmission and transfer case combo out of an old 4x4.

you have splines in and out, and if you put the t-case in low range, there must be some combo that will give you something close to what you need.

 

[brokenot]

After weeks of trying to get a service call they showed up and charged me $150 for a thirty minute service call to tell me that the windings had came apart.

There are lots of places that can do a rewind if new parts are cost-prohibitive.

Here's one example:

Eurton Electric | Motor Rewinding & Parts

Their site says motor rewinding, but they'll do rotors and stators for gensets too. Going that route will be much easier than adapting several mis-matched components together. Download their complete rewind catalog and take a peek....they do have a couple of generator pages that can give you some ideas on pricing.

 

[jburd964]

Thanks for input. Sounds as though you have a better understanding of gear reduction/rpm required then myself. The gear & chain or belt pulley sounds feasible.

 

[jburd964]

The new part is $1000 plus labor and I figured I'd be no better off then when I started. If it was rewound that would include the stator as well to remove all aluminum at best guest .but still no guarantee

 

[alco141]

first thing to do is call the manufacturer and complain a lot, let tem know how unhappy you are about the shoddy manufacturing process they used, talk to the supervisory personnel and go to the big boss , they may give you a deal on the repair. this is a substandard manufacturing process, and needs to be addressed. i would not let this go without voicing my displeasure to the powers that be, write a letter, make some noise, you may be pleasantly surprised at the outcome, what is doing this cost you?

alex

 

[lostcause]

i'm going to question the reduction ratio... i didn't see the original poster mention 3600rpm, though i may have missed it somewhere. generally small gas engines (sub-10hp) are in the range of 3600rpm, but most of the larger 15hp & up ones i've seen are meant to run closer to 1800rpm speed. at that speed you'd be looking at more of a 3:1 or 3.5:1 ratio. again, i'm just guessing as to the engine. it could be 3600rpm, but i'd bet closer to 1800.

i know it doesn't seem as elegant, but i'd go for a belt drive. i assume there is a straight shaft on the engine, and maybe there's a way to put a pulley system on the generator head? enough of a straight shaft before the splines? i don't know what you can find easily for pulleys and belts, but for that kind of power i'd think it would require a larger than normal v-belt, or a multiple belt pulley setup? again, just guessing. i'd bet that there are some small engine shops that could make suggestions based on what they may have seen. if it is an 1800rpm engine, a 3" pulley on the engine and a 10" pulley on the generator would be exactly 540rpm at the generator.

 

[aczlan]

first thing to do is call the manufacturer and complain a lot, let tem know how unhappy you are about the shoddy manufacturing process they used, talk to the supervisory personnel and go to the big boss , they may give you a deal on the repair. this is a substandard manufacturing process, and needs to be addressed. i would not let this go without voicing my displeasure to the powers that be, write a letter, make some noise, you may be pleasantly surprised at the outcome, what is doing this cost you?

You might get lucky and they might replace the whole unit for you. Then you could sell it and get another one.

Aaron Z

 

[J_J]

i'm going to question the reduction ratio... i didn't see the original poster mention 3600rpm, though i may have missed it somewhere. generally small gas engines (sub-10hp) are in the range of 3600rpm, but most of the larger 15hp & up ones i've seen are meant to run closer to 1800rpm speed. at that speed you'd be looking at more of a 3:1 or 3.5:1 ratio. again, i'm just guessing as to the engine. it could be 3600rpm, but i'd bet closer to 1800.

i know it doesn't seem as elegant, but i'd go for a belt drive. i assume there is a straight shaft on the engine, and maybe there's a way to put a pulley system on the generator head? enough of a straight shaft before the splines? i don't know what you can find easily for pulleys and belts, but for that kind of power i'd think it would require a larger than normal v-belt, or a multiple belt pulley setup? again, just guessing. i'd bet that there are some small engine shops that could make suggestions based on what they may have seen. if it is an 1800rpm engine, a 3" pulley on the engine and a 10" pulley on the generator would be exactly 540rpm at the generator.

If he is talking about this 30 HP Kohler engine, then it will run at 3600 rpm.

Kohler Engines: CH750: Command PRO: Product Detail: Engines

Even the Kohler diesel runs at 3600 rpm.

http://www.kohlerengines.com/onlinecatalog/productDetail.htm?productNumber=KDW1003

What is the model number of your Kohler?

 

[jburd964]

Just pulled up pdf and the newer ones are running 30hp @3600 rpm's. Probably another cost saving intervention. Will look for manual tomorrow but this is probably going to be the right number from the sound of it running it was high rpm. Y'all keep'm coming it's en-lighting.. I wouldn't mind a pulley set up. Another reason for wanting to set this up in this fashion is so that if I'm not home wife could be shown how to line it up without using tractor. I would like it to work reliably and safely..

 

[jburd964]

I raised **** from the bottom of the valley to the top of the mountain. They didn't seem to mind at all they just gave me lip service. They know what their selling and if the news doesn't get out their making a fortune. That's why I went into detail in the post. It's a shame but its all about the dollar. Company's now a days just don't give a crap about customer service their worried about customer turn over. Go to you local box store and ask for something that requires more then showing you something general location and see what you get. 1 in 5 can can't answer past the basic. Before and after storm arrival you can hardly get a returned phone call unless your looking for a new unit and setup. Then it's the same thing all over again after the passing. People want them before the storm and everbody that went without power during the storm wants one after. When i called for the service call it took 6 six week for them to make it over, they were selling and installing new clients not working on the ones with problems. They already scored on them. I've research looking for ofter similar problems and there not hard to find. Another problem they have is engines slinging rods. I stealing this from ( aczlan) Hate is like taking poison and wishing your enemy would die. But that;s were I ended up.

 

[lostcause]

If he is talking about this 30 HP Kohler engine, then it will run at 3600 rpm.

Kohler Engines: CH750: Command PRO: Product Detail: Engines

Even the Kohler diesel runs at 3600 rpm.

Kohler Engines: KDW1003: Kohler Diesel Liquid-Cooled: Product Detail: Engines

What is the model number of your Kohler?

wow, i never realized that engines that size were 3600rpm. they must be screamers. guess you couldn't go direct with a belt then - would be a 3" pulley to a 20" pulley - kind of a little unreasonable. i guess you could make a jackshaft setup. go with the 3" pulley on the generator and 10" on the jackshaft. this would put the jackshaft at 1080rpm. then run a 3" pulley form the jackshaft to a 6" pulley on the generator - back at 540rpm. just mount the jackshaft between some pillow blocks and i'd think it would work. i guess first i'd see what i could find for reasonable pulleys that will fit your pieces.

 

[J_J]

I have a Honda engine with a gear reduction but I don't know the output rpm. It might be close to 6:1. I don't even know the HP right now.

 

[jburd964]

After much researching after the fact and leaning what to look for I'm going to say the basic's of my insight. First and foremost I would say is the windings. It's not going to be something that is advertised but can be found are questioned to sells person. Second is going to be the generators rpm's.They run at either 3600 are 1800 rpm's. This is also like the engine if its running at half speed it should equate to twice the life span. The lower rpms are commercial grade but at 1500kw you looking at about a $650 upgrade. With that up grade you get the lower rpm as well as copper windings. I also decided to pass on the added expense of the nat gas engine fearful of another catastrophic failure. My tractor is payed for and burns diesel at .25 gal per hour 100 gallons equals 400 hours, ant bad. But still have that $8000 engine set around and wouldn't mind using it up.

 

[jburd964]

I'm looking to do more resaerch and something will turn up. let me know.

 

[3930dave]

A friend of mine had a 12kw Generac of that vintage installed at home. Various things (that shouldn't have) failed < 100 hours of use. Same experience (Muskoka, ON, Canada) with lack of field service, it was like pulling teeth, virtually regardless of what you were willing to pay.

Their take away was to plan to go with Onan, or some other (real) industrial grade product if/when they do this again. Their view (now) is that the initial higher costs will be offset by reduced operating costs, and enhanced peace of mind.

D.

 

[mrcaptainbob]

Yearsa ago I was at a big box store looking at generators with my wife. A customer overheard and started sharing his experience with me. He HIGHLY recommended NOT going with Generac generators. I bought a Coleman and am pleased. I also have interacted with Eurton on a very small scale. They were very helpful to me, courteous and quick.

 

[jenkinsph]

I have an Onan Quiet Diesel commercial genset on one of my service trucks and have been well pleased with its service. Uses a Kubota diesel engine and is available in various models with single phase or three phase outputs. Much less noise and lower fuel comsumption that the Generac in question.

After having several problems with this same Generac unit we finally got a line from the power company installed and junked it out. This was in a remote area of a ranch and the lp truck driver hated to fill the tank too.

The larger Onan diesel gensets about 8000 watts and up use very little fuel at no load or light load so the cost of operation is very reasonable. Very simple to operate and easy to teach to anyone (even my mother).

FWIW, I would have loved to have the 30ish hp motor on my 14' miniature Lafitte skiff when I was growing up.:laughing: Would have been great for some of those canals filled with water lilly's. I do miss the good times fishing and growing up in south Louisiana.

 

[3930dave]

I have a small Coleman (2500w continuous, reasonable size for its day), seen light use (no problems so far, knock wood), mostly during our big ice storm in '98. Decent product, for what it is.

Thnx for the Onan comment Jenkin.... further confirmation of the general impression I'd had so far. I've noted heavy Onan use in the RV world, and often seems to be what the big utilities around here run on their trucks.

Next step for me is likely a PTO gen, the only real challenge would be having my better half run it... but that would be doable too (assuming I've (mechanically) hooked up the gen, before going out of town).

I really feel for anyone with gen problems.... you spend the $$$$ to deal with a bad situation ahead of time, and get let down..... part of the reason I lit up the keyboard is to help get the word out on Generac. My buddy with the problem(s) has plenty of engineering smarts (and then some), and money, and the Generac was a real PITA for him to deal with..... thnx to sites like this, we can get the word out.

D.