PTO Generator Project

[aarolar]

So not sure if this is the right place to post this but here goes feel free to move it if needed.

I have a generator I dug out of the trash dump and I actually managed to get it working for a short time during the ice storm this year but had horrible blowby from a completely wore out cylinder. Something like 50psi compression last I checked. So now I've got the wild idea to hook the generator to the PTO on my little Yanmar tractor.

I need ideas on the semantics of the idea, obviously I will need to use a jackahaft to get the RPMs where they need to be on the generator. The tractor has 3 PTO speeds 540,750 and 1000. I would ideally like to run the tractor slightly above idle for fuel and sound reasons. The tractor is a 13hp twin inline cylinder diesel so I feel comfortable saying it should have no issues power wise. What issues do y'all forsee in my plan the biggest question mark in my mind is how much life is left in the generator and if it may be rebuildable?

 

[hamish]

Input rpm of the generator will be 3750-generator, to give a loaded rpm of 3600. The crankshaft on that motor is tapered which can complicate things a little.

The easiest way to achieve your goal is to remove the recoil assembly and mount a pulley on the starter cup. The couple it via a belt to the appropriate pulley mounted on your jackshaft.

 

[aarolar]

Access to a full machine shop CNC lathe and two mills machineing a tapered adapter is no issue. I want to keep this as clean and professional looking a possible.

 

[Pelorus]

Is a (cheap pseudo Honda) gas engine to re-power that genny not an option?

 

[aarolar]

Is a (cheap pseudo Honda) gas engine to re-power that genny not an option?

Sure but then that's just another small engine to worry about taking care of and ethanol fuel in. The diesel is quieter, more fuel efficient and more reliable all the way around.

 

[brenndatomu]

A belt driven overdrive arrangement would be about the easiest way to go about it IMO. It should be pretty easy to find off-the-shelf parts to accomplish this. I'm not sure about being able to run at an idle though, that would be a ton of overdrive, also the tractor HP at idle is gonna be pretty low, rated HP is probably at what, like 2500-2800 RPM? What was the generator engine HP?

Edit: Do I spy an SS Elk back there?

 

[aarolar]

A belt driven overdrive arrangement would be about the easiest way to go about it IMO. It should be pretty easy to find off-the-shelf parts to accomplish this. I'm not sure about being able to run at an idle though, that would be a ton of overdrive, also the tractor HP at idle is gonna be pretty low, rated HP is probably at what, like 2500-2800 RPM? What was the generator engine HP?

It was a 9hp I think I'm not looking to run at idle but maybe 1500-2000rpm range the rated HP is at 2600 that last 600rpm seems insignificant but it gets pretty loud around 2200rpm. If I find I need full rated HP I can it's not an issue but imagine the inline diesel has a good deal more torque than the single cylinder gas motor and should go along way.

 

[Pelorus]

Am interested to hear how your PTO idea turns out.
I have a Generac gas genny purchased pre year 2000 (the sky was predicted to fall) and that sucker is the most reliable piece of motorized equipment I own. I turn the fuel off and let it run till it quits, then it hibernates. Consistently starts on first or second pull after sitting for 6 months or more.

 

[Sawyer Rob]

I have a PTO genset and most of the time I run it on a small Kubota about the same size as your Yanmar.

When I shift the PTO into a higher speed, there's all kinds of problems that crop up. One, you have a fairly big power loss, then the governor doesn't respond to loads fast enough and the RPM goes up and down giving a poor sine wav...

I've found, unless I'm just trying to run a drill or some other SMALL load, it's BY FAR best to use the 540 speed on my PTO.

It takes a LOT of gearing to get from 540 RPM's to 3,600 RPM's!!

SR

 

[hamish]

Access to a full machine shop CNC lathe and two mills machineing a tapered adapter is no issue. I want to keep this as clean and professional looking a possible.

Ok, so to go along with the tapered input shaft you will require a bearing support and mount to replace the crankcase cover on the existing motor which will support your puller/drive arrangement and act as a mount for the gen head. Consider driving the generator head of the crankshaft of your tractor engine, which will make your gearing requirements easier, and will not require the higher engine rpm to attain the PTO rated speed. In doing so you have to add a throttle stop as too high of an rpm will damage the gen head.

 

[aarolar]

Looking like a 14" pulley on the PTO and a 2" pulley on the generator input will put me in the sweet spot.

 

[brenndatomu]

You'll need to look it up, but I bet you'll need to go to a double pulley or more

 

[Whitespider]

I'm surprised no one has asked the first question... what is the rated wattage of the gen-set and what are you planning to power with it??
The generator don't look all that large in the picture, and a 9 HP engine sort'a confirms the output wattage ain't all that high (maybe 3500 watts?). You're talking about building some sort of apparatus to ramp-up RPM's from the tractor, plus mounting and lord knows what else... and even rebuilding the generator head?? You can buy a new 3200 watt generator from Harbor Freight for $339 right now‼ They get (mostly) great reviews and my 6500/5500 watt has been rock solid. By the time you finish your project (and work out the bugs), I'll bet you have close to that much in it (belts, pulleys, bearings, hardware, steel, and-who-knows-what-else)... and you still have an unknown in a used generator head‼

I see several problems with your plan... but I'll point out the big one. Over driving a gen-set will damage it, so will under driving it, and excessive fluctuations are worse yet. By using some sort of up-gearing any RPM fluctuations at the PTO will be magnified at the gen-set... how responsive is your engine/governor setup?? Not to mention that fluctuating generator output can damage or destroy the equipment it powers. Not all gen-sets are created equally... they are designed and engineered to be (relatively) steady and reliable for a certain type of power source. You can buy PTO generator heads, even pulley-driven generator heads... but a portable, small gasoline engine gen-set likely won't work with your plan.

Heck man, the cheapest, quickest, and most common sense solution is to slap one of those $99 6½ HP Harbor Freight engines on it... done‼
(Engine size would depend on rated wattage... but they use the 6½ HP on their 4000/3200 watt generator.)
*

 

[aarolar]

I'm surprised no one has asked the first question... what is the rated wattage of the gen-set and what are you planning to power with it??
The generator don't look all that large in the picture, and a 9 HP engine sort'a confirms the output wattage ain't all that high (maybe 3500 watts?). You're talking about building some sort of apparatus to ramp-up RPM's from the tractor, plus mounting and lord knows what else... and even rebuilding the generator head?? You can buy a new 3200 watt generator from Harbor Freight for $339 right now‼ They get (mostly) great reviews and my 6500/5500 watt has been rock solid. By the time you finish your project (and work out the bugs), I'll bet you have close to that much in it (belts, pulleys, bearings, hardware, steel, and-who-knows-what-else)... and you still have an unknown in a used generator head‼

I see several problems with your plan... but I'll point out the big one. Over driving a gen-set will damage it, so will under driving it, and excessive fluctuations are worse yet. By using some sort of up-gearing any RPM fluctuations at the PTO will be magnified at the gen-set... how responsive is your engine/governor setup?? Not to mention that fluctuating generator output can damage or destroy the equipment it powers. Not all gen-sets are created equally... they are designed and engineered to be (relatively) steady and reliable for a certain type of power source. You can buy PTO generator heads, even pulley-driven generator heads... but a portable, small gasoline engine gen-set likely won't work with your plan.

Heck man, the cheapest, quickest, and most common sense solution is to slap one of those $99 6½ HP Harbor Freight engines on it... done‼
(Engine size would depend on ratted wattage... but they use the 6½ HP on their 4000/3200 watt generator.)
*

Buzzkill...





But no seriously everything you bring up is valid particularly the life left in the genset and rpm fluctuations. The biggest advantage for me is having a generator powered by a fuel efficient water cooled diesel motor plus one less item to worry about maintaining as I have a list of crap as long as my arm now. Also diesel is easy to store long term compared to gas. The genset is rated at 5500 watts and ran the important stuff fine plus allowed me to run the well as long as I shut all my other stuff off first, and that was with the wore out Kohler.

 

[kingOFgEEEks]

We have a larger genset on the farm (I'm not sure how many KW, but it is enough to power the barn and house simultaneously), and have had good luck running it on the 1,000 RPM shaft of the tractor, although it is rated at 540. You just have to adjust the engine RPM's accordingly so you still get 120/240 Volts on the genset.

Now, there are two things to keep in mind here:

1 - the genset we have was designed and built to be run on a tractor PTO.
2 - the tractor we are using is an IH/Farmall 1066, so I am working with 126 rated PTO horsepower on a 6 cylinder IH Diesel instead of a small Yanmar Diesel.

In our experience, switching from our Allis Chalmers 180, which had 65 PTO horsepower at 540 RPM, to the larger tractor idled down on the 1,000 RPM shaft, we actually burned less fuel.

I think that if you could find the right gear driven reduction, you could run your tractor to power this thing, but don't be surprised if it works that little tractor pretty hard. If it actually does match up well, I wholeheartedly agree that you will probably save a significant amount of fuel cost compared to the small gasoline engine. Diesel engines do a very good job of matching fuel consumption to engine load.

 

[Sawyer Rob]

I think that if you could find the right gear driven reduction, you could run your tractor to power this thing, but don't be surprised if it works that little tractor pretty hard. If it actually does match up well, I wholeheartedly agree that you will probably save a significant amount of fuel cost compared to the small gasoline engine. Diesel engines do a very good job of matching fuel consumption to engine load.

From my own experience with these small diesel tractors, I'm betting he won't have the same result you had. First of all, he's a bit under powered for the job now, (at 540 RPM's making 5.5K) and also those older imports just don't have the governor control that the newer compacts have...

Like I posted above, it doesn't work so well with these small tractors, and my Kubota is a newer design...

SR

 

[deutzman]

I have a 12 kw run 15 surge pto generator. Manual says 24 hp required. It's rated for 540 rpm also. I use a 100hp Deutz Fahr tractor and run 1000 range on the pto. Engine is turning 1,200 rpm to get 540 off the pto. It works great. Turn on the 2 biggest loads at the same time and tractor never changes tone. I've run extended times and uses 0.7 gal. per hour. It's a modern tractor, water cooled and fuel is controlled by load. Can use up to 3.5 gal. per hour running 7 shank chisel plow. It idles at 900 rpm so 1,200 is easy on the engine. 2,200 is normal 540.

I think you have a good idea but may come up short on HP. Tractor data says you have 16 engine HP. I'm sure you can run it at 540. It may be iffy on the 750 and 1000. It'll be interesting to see what you come up with and how it works. If you have access to a VOM that'll display HZ it'll help you see what's going on. Keep us up to date and good luck.