Generator Belt-driven vs PTO-driven generators

[RPM]

OK - so I'm being super-detailed in my study of what generators are out there. I'm trying to get a grasp of what's what though.

Since they don't seem to make PTO generators with ratings around 8000W - all I really need or want to run off my BX2200 - I ended up looking at belt-driven generators. This raised a question for me. In the picture below is a 10,000W belt-driven generator (courtesy of Northern Tool). The drive shaft is on the back right ... you can figure it out.

This costs $569.99

The next picture is of a 12000W PTO driven generator ... note the gear box and PTO coupling on the back side attached to the drive shaft of a generator otherwise the same as above.

This costs $1899.99

So I am left scratching my head here. Allowing for a bit of a difference in price due to different power outputs, the only difference I see is a gearbox and PTO shaft coupler. Is that really a $1000+ item?

If not, does anyone know where I could get one? I'm assuming it has a couple of gears in it, some oil and then the PTO shaft coupling. I'm hoping it would make an 8kW PTO generator a possibility for under $1000.

Am I missing something? It would be great to hear back from someone with practical experience.

Patrick

 

[Harv]

Patrick -

I have no practical experience (with a lot of things), but I'm guessing the price difference has less to do with the cost of parts than it does with the ol' supply and demand concept. There must be a lot more belt-driven units on the market than their PTO-driven counterparts.

Sounds like a fun challenge to adapt the belt model to run off your PTO. Simple approach might be to rig a PTO shaft to turn a pulley.

Did I mention I have no practical experience? /w3tcompact/icons/crazy.gif

 

[RMulkey]

Patrick,

I suggest you check the 'Load Factor' or Continuous Power Factor on both. A 1.0 LF means the generator can be run continuously at the rated output. 0.8 means 80% and so on. Do the units have the same type of and size of bearrings and so on... Overloading and small bearings are a bad combination. Most PTO generators are rated at a 1.0 LF with a 1.5-2.0 startup current ratting. The same may be true for the belt driven units you are looking at, but you may want to check. Also check the cost of the actual drive belt hardware verses PTO drive shaft. If you already have a PTO shaft that could narrow the $$ difference. From the pictures you showed, the 12kw generator looks like a Winco farm (continuous) duty with a oil bath gearbox (the better quality).

8kw to 12kw is a 50% bigger generator plus the bigger unit just looks better built. The better generators run at lower RPM (1800 RPM vs. 3600 RPM) and last a very long time if not overloaded. Remember 1.0 LF means you are not overloaded at the rated output at the max ambient temperature allowed. Also the rule of thumb is 2hp per 1kw or output.

You may want to check out http://www.friesen.com. They have some smaller 10kw PTO generators but I think they may be even more expensive than the Winco 12kw.

I cannot remember where, but I have seen 8kw PTO generators discussed in some old threads.


Hope this helps.
-Roger

 

[RMulkey]

By the way. I am not a fan of PTO generators at home or the ranch for anything other than emergency power. If you use a generator a reasonable amount, putting it on and off the tractor is a pain. You always have to drop the current implement, and attach the Generator. And then you don't have the tractor available any more. I have bottomed out on a 6500W Honda comercial generator I use all the time (6500w peak, 5000w continuous).

 

[ScottieM]

I looked into getting a pto generator, but after thinking about alll those extra hours I'd be putting on my tractor, I decided to go with a 10kw Natural gas/Propane generator that is connected right to my "big" propane tank. I bought it from the same dealer I bought my B7500 from.

 

[patrickg]

Patrick (RPM) Glad I'm not the only voice crying in the wilderness about the various shortcomings of tractor driven gennys. If it really does fit your intended use and you have addressed future growth and expansion AND it will be a low usage item and you just want it, then go ahead but try to see the top 2-3 competitors in the "flesh" as there might be a world of difference in construction robustness and bearings.
How reliable does this need to be? What about availability? Would it matter if the tractor were out in the field with a flat tire and couldn't be brought to the genny for a few days due to rain or civil war. What if the tractor were at the dealer for some sort of work when you need power? If it is a tool then it is just an anoying inconvenience
B U T if it is to keep your freezer and frige operating or something important (not neccessarily an iron lung but important to you) operating then I think I would consider a stand alone.
I really do like multi-use tools and see the economics of them (I have some) but I suggest you do a little requirements analysis, worst case usage analysis,and risk analysis.
If you do opt for a belt driven unit be sure to select bearings rated for the side loads involved with belt tension and build a truly fool proof (child proof too) belt guard. Murphy spends extra time studying belt driven stuff.

And most importantly.... let us know what you finally decide and how it works for you (pictures too?).

Patrick (patrickg)

 

[kevinro]

I had considered getting a PTO generator. After additonal thought, I realized that I needed the generator when the power goes out. Living in the Pacific Northwest means that the power goes out when 1) A wind storm knocks trees down or 2) A snow storm knocks trees down.

I realized that chances are strong that if the power is out, I will more than likely need my tractor to move trees.

Kevin

 

[patrickg]

Kevin, There are lots of reasons, I'm sure, for having PTO gennys but frequently there is conflict such as you have mentioned when the genny is for emergency use. If I had two tractors I'd have a combo genny/welder with PTO drive most likely as it would be a good economical tradeoff AND I have other means of generating power or welding or both if it were an emergency situation. But then I am sometimes a belt AND suspenders kind of guy.

For example, I have installed a direct vented propane powered gas log (55,000 Btu) as back up heat in my mom's new all electric house. Last winter there were a few ice storms with one causing a 5 day electric outage (folks within a few miles of here were out for weeks, I missed that on a quick trip to SOCAL). You can get along for a while eating out of cans and making sandwiches but freezing in your own house or your pipes bursting isn't good. I have installed an auxillary propane outlet to run a BBQ unit (with no bottles for her to wrestle) that can operate an emergency cooking facility (Coleman propane fired camp stove) in the well vented sun room via a hose. This can heat water for a "sponge bath" also. She still has kerosene lamps from "way back when" so won't be in the dark. I have a small Honda genny if TV becomes important (also two 12 vdc TVs)

What I was illustrating here wasn't a "perfect" solution but was intended to show redundancy and work arounds. No reasonably probable weather phenomenon would constiute a crisis, just an inconvenience. If a generator is a requirement in this situtation it should be stand alone so the tractor can clear long driveways of snow or fallen limbs. I'm still not entirely comfortable with electric cooking and hot water but having emergency backups to replace each, albeit with loss of convenience,lessens my concern. If I had it to do over again I would have wired the place for at least one 12 vdc fluorescent per room and installed a couple Trojan golf cart batts in the garage. I don't like the smell of kerosene lamps nearly as much as the smell of diesel passed lightly through my Kubota.

Patrick

 

[RichNJ]

I had the same question. Does a gearbox and some bolts cost $1,000? I found the gearboxes here: http://www.bypy.it/

I have not had time to research. Please - if you find anything let me know. If all else failed I will probably get the belt driven version and use pulleys and belts. This way I can taylor the engine speed to match the generator speed. At 540RPM my L4310 is putting out much more HP than a small generator can use.

 

[DaleW]

Rich,

Be careful about matching engine speed to gen speed. These generators are made to be run at 540 input rpm to produce 110/220 output volts. As the speed decreases, so does the voltage. It's like having a brownout....not a good thing for appliances, tv's etc.