Anyone here have a PTO generator?

[Soundguy]

I'm not in full agreement with soundguy about power needs. 7.5kW converts to 10HP and even with a 20% loss for the drivetrain that be about 12 HP input and not the 15HP using the 2HP/kW. Not a big thing unless you're on the borderline of available power.

I said 'about' to denote that was not a hard and fast number.

If you look on the internet, you will notice many of the pto genset manufacturers are quoting ~about~ 2hp per generated killowatt.

I agree that direct hp to kilowatt conversion is not 2:1.. however you have to take into account many inneficiencies.. You also need to look at peak loads.

If you take that 10.x hp # for the 7.5kw genny and drop max load on it, yuo will do ALOT better having a 15hp power reserve to carry that load than an anemic ( math looks good on paper ) engine to carry the load.

In fact. the larger engine you have, the more rotational mass you have. While my 12.5kw genny can drag down my old ford 8n ( 26.x) pto hp a little on a large electrical motor start .. my ford 5000 ( 67 pto hp ) and my 7610s (~90 pto hp ) don't even twitch when I throw a large mixed load of motor starts including well and hi- incandescent laods and power tool starts...

I'd rather have too much engine and experience a little lowered 'average' fuel economy, than have an anemic 'just barely able to work in an ideal environment' engine when i really need power.

soundguy

Soundguy

 

[JamesH]

I have been looking at building my own ST powered PTO generator also.
Below are some of my thoughts. I could use a bit of engineering help.
I cannot find a good source of V ribbed pulleys. Like all the cars use now.
So looking closer at sheaves for V belts in the Grainger catalog.
I can get a 15.4" and a 4.6" O.D. sheave. This gets me to 3.333 multiply factor.
These diameters are figuring a BX size belt.
Both sheaves accept a B type split taper bushing. The bushing for the small sheave needs to be 42mm or 1 11/16". I hope that is close enough. The bushing for the bigger sheave is arbitrarily selected at 1" for the input shaft.
So, I have a 1" shaft machined so that the PTO shaft fits on one end. The shaft is supported by a couple of pillow blocks and the opposite end of the shaft has the large sheave on it driving the gen head.
Fabricate a frame and guard for the pulleys.
Are we there yet?
BTW, my tractor is 32HP PTO, I plan on getting a 20kW gen head. A little big for 32HP but the extra capacity won't hurt, I just won't make the full 20kW.
James

 

[Soundguy]

For sure you will never exceed the heads output capabilities... that extra copper won't hurt.

Soundguy

 

[Mickey_Fx]

What you've described is very sim to what I had in mind if I were to build a genset using an ST gen head. One difference I have going for me is my tractor has a 4-sp pto and I could get by with a 2:1 drive ratio.

James, do you live anywhere close to a town/city where there is a chance there is an industrial supply house that handles power transmission type products? I think they could help you with the sheeves and belts. You do need to refer to a chart with info on how much power you can transmit for various belt sizes and pulley dia. The smaller the dia the smaller the power.

Did you plan on mounting the sheeve on the drive input shaft on the end or between the bearings? I like between the bearings but that makes for more work to change belts. Have you given any thought about using a chain drive? Think the drive components would be lower cost and easier to deal with the drive if the drive pulley/sproket was mounted between the bearings. Drive chain shouldn't be any problem at all and o-ring style chain would keep lube considerations to a min. Could also handle smaller sproket dia. And chain drive isn't as sensitive to drive tension as a belt drive.

You should consider a guard regardless what kind of drive components you end up using.

 

[JB4310]

Does anyone make a 4 pole st type pto generator?
or a link to diesel driven 4 pole gen sets, been reading a little about the Chinese 4 pole heads, seems like they are making them the way we use to make things, to last, don't know if I would trust their power plants though.

 

[Mickey_Fx]

JB try out Generator Heads, Generator Ends, Homemade generator, DIY Generator, Small Diesel, Generator, Lister, Listeriod, one cylinder diesel, Asian Diesels, off grid power, custom pulleys, custom sheaves, for some interesting reading. Lots of info on ST gensets.

Like with many things from China, you can find the same items being built by different Co's and qlty varies from poor to quite good. Some importing ST gensets are having mods made at the factory. Chinese bridge rect are not that great so some are using better qlty parts from other countires. Same thing about the bearings. While they are std size, they are open and hand packed with grease. Better models come with better bearings.

Believe Utterpower is getting their gensets from a fellow that sells on e-bay with name of sawyer335. Here is a listing he has on e-bay with some useful info. NEW HD 5 KW GENERATOR HEAD END DIESEL GAS NR - (eBay item 110189125530 end time Nov-11-07 16:30:00 PST)

 

[JB4310]

Thanks, alot of stuff there to digest, what does the ST stand for anyway? I really like the idea of the slow turning equipment, less effort, fuel, wear and tear etc. plus simple design, maintenance and repair.
I know those machines are designed for near 24/7 operation which is not what I need, just figure if they can handle that, they must be the most reliable in a survival type situation.
Can't you get a pto gear box and direct couple it to the head so you wouldn't have to deal with the belts, shafts, blocks and sheaves? just thinking out loud. All this talk about slow turning motors makes me wonder, is it easier for the tractors governor to maintain constant speed under changing loads if it's already is at a higher rpm as opposed to running at lower rpms, risking greater fluctuations in voltage and frequency, if that's the right term.

 

[JamesH]

Mickey,
Your doing the same thing I am except one of your pulley's/sheaves is just a little different size.
Where am I going to put the drive pulley? Not sure, that is what I could use a little help with.
I am thinking a round bar supported on each end by a pillow block. One end of the round bar extends past the pillow block and connects to the PTO shaft. How do I adapt that without having splines cut in the round bar? Between the pillows is the drive sheave or sheaves. Two may be best running two belts. One or two more sheaves are also mounted on the gen head. The gen head would be mounted in such a way that the belts can be tensioned.
How do I keep the round bar from sliding back and forth between the pillow blocks? Pin a collar against them?
I kind of like the idea of using belts. Another sheave could be added to drive a alternator for DC charging if needed.
JB4310, A gear box would be ideal. But I have yet to find one readily available that will increase the RPM. Reduction is quite common but I am not sure they can all be used in reverse.
When I do buy the gen head I will get it from sawyer335 as he seems to have the best reputation among those selling them.
Keep the discussion going, we are getting there.

 

[Mickey_Fx]

James, for the bearings, use one that have a locking collar on them. Pillow blocks come with this type of bearing.

If you read the info on utter power, seems like they are pushing the multi-V automotive serpentine belt drives and they are selling custom made sheeves for these. If going convientional V belt, you really want to go with multiple belts 2-3.

I'd prefer not having a sheeve cantilevered off the end of a shaft but have not spend any time doing the math on shaft flex due the the belt preload. You can buy adapters to get from the pto shaft to the sheeve shaft. A power transmission supplier or a farm equipment dealer should be able to help you out.

For me, if I would decide to build an ST genset, I'm only 30 mi S of Portland and I can drive up there and pick up what ever I get from Sawyer335. Already spoke to him and he didn't have any problem with doing that and elmin the high cost shipping.

Keep us informed of your progess.