540 PTO RPM and engine longevity

[getut]

I have been lurking in all the generator threads that occured as a result of all the hurricanes. I am in the market for one of the PTO generators myself but am curious about the longevity of my tractors engine when I run at 540 PTO speed.

I have a Kioti CK20HST and have noticed something that seems to be common to the hydrostatic tractors (but I may be off base). It seems that 540 PTO speed on every brands HST tractors puts the RPM's alot higher than on geared tractors. On mine 540 PTO RPM is at 2800 engine RPM. I almost never run my tractor that fast because it ***seems*** really fast when your on it (almost to the point of a runaway). Its really noisy and I don't notice any difference in cut quality with my RFM when running at around 2200 engine RPM.

I would not have any choice but to run at 540 PTO speed if I went the PTO generator route. Does anyone see any issues running my diesel at 2800 RPM for hours on end in a power failure?

Also.. as a side note... I have VERY much considered just buying a belt driven generator head of around 10KW and building a platform that goes to my 3 point hitch. I would use a PTO shaft and pulley system to gear it down a little and let the engine run at a much nicer RPM. Not very difficult with the exception of finding all the pulleys readymade (I have no fabrication capability at my home nor access to any at work). I can borrow a welder and build a table to mount everything to with the 3point hookup arrangement... but I suspect the needed pulleys (especially one with a center ready to accept a PTO shaft are going to be a different story and be difficult to obtain ready made). The pulley for the generator side would probably be a readily available item.

I rambled alot during this and probably should have started 2 different threads... if the home made genny point over rides the other question, I'll start a new thread tomorrow.

Getut

 

[Soundguy]

A lot of this was covered in the pto genny thread i started.

First.. pto rpm is pto rpm.. If it is 2800 on your machine.. and you run at 2200.. that cutter is turning at 424 rpm...

As for running the engine at pto rpm for extended times...? what do you think the tractors made for? Do you ever mow with it? I used to mow for hours on end.. Now that I have a bigger tractor it takes me less time.

Keep in mind that tractors used to be used to pump water and run sawmills and gristmills... all day. Running at rpm speed.. under load isn't bad. It oyu aren't runnint it with a load, I would shut the genny down. If I weren't going to be using power for a few hours I'd deffinately shut the tractor off.

The genny heads you commonly see usually need 3600rpm drives... though i have seen 1800 rpm drives.

A custom pulley setup or a gearbox is feasable.. but at the cost of fabrication.. a comercial unit is probably cheaper... I paid 999 for my 12kw pto genny... and another 150 for the pto shaft.

That 10k head is how much? And the custom belts, pullets, and gearing is how much?

Soundguy

 

[slowrev]

Another consideration is belt slippage causing low frequency and burning up your fridge, etc... Can be done, but I am with Chris on this. If I had a FREE generator head I might try it, but would want to use a cog belt.

 

[KennyV]

I always thought an overdrive for the pto might be nice. And a while back there was a discussion about a selector kit for the rear PTO on Kubota tractors. That kit will give you a choice between 540 and 1000 pto rpm. Thus your engine will be running at less than half speed to accomplish 540 while in the 1k setting, still good torque.
This will accomplish what you want to do and it will put less load on your mower. Mowers cut using velocity.
The reason I did not pursue it … I could not find that discussion again, and I figure It is not that critical to operate a diesel engine at load most of the time. KennyV

 

[Jim_Fisher]

getut,

</font><font color="blue" class="small">( I would not have any choice but to run at 540 PTO speed if I went the PTO generator route. Does anyone see any issues running my diesel at 2800 RPM for hours on end in a power failure? )</font>

The power lines end at my transformer. Because of this, I'm generally the last to have service restored after a storm. Sometimes I have to run the generator for several days.

My generator produces 60hz at about 2550 rpm, which is 150 rpm below rated speed.

I make sure that I shut down every twelve hours to refuel, check all fluids, and grease the PTO shaft. I suspect that the hours running the generator are the easiest hours that I put on the tractor.

 

[texbaylea]

I just traded in a Kubota B6100E that once used to operate a PTO generator for 10 days straight after a hurricane. I had to stop the unit about every 4 hours to refuel and to check the tractor. That tractor gave good service for the 22 yrs I owned it. In fact it was operated at rated speed 95% of the time it was used.

Vernon

 

[getut]

Ok.. thanks for the replies (all of you). I guess I am worried about nothing.. its just that the difference between say 2200 RPM and 2800 RPM really seems to make no difference on my tractor with any attachment like RFM or rotary cutter except for noise.

The 10kW head I was looking at really on 7KW with 10KW surge... but it was only $299.

If I decide to go the do it yourself route this is what I will most likely go with:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45416

If I go with a ready made unit, I am leaning in this direction:
http://www.tiger-power.com/generators/pto/default.asp

Even though you guys have instilled some confidence in me about running at 2800RPM for hours on end, I don't think there is any question that 2800RPM is more stressful on the engine than 2200RPM, even if that difference is only slight. So after more research if I am able to find 2 pulleys of the required dimensions and with the correct hubs, then I will definitely go the DIY route. I cogged belt may not be an option but shafts with stacked pulleys is the way I will go (if I find them at all).

I would want a heavy, large diameter pulley(s) attached to the pto shaft to give some flywheel effect and help carry it through surges. An 18" drive pulley and 2.1" driven pulley would be very close to what I need.

Getut

 

[RonR]

Getut,

I'm not an engineer, but I'd be nervous that a 2" driven pulley by the time it spreads to an 18" pulley wouldn't have much surface contact and could easily slip. Maybe if you can serpentine it around, it would be ok, but that takes more stuff.

I suggest you check with someone that knows or has done this to make sure slippage is not an issue. I just don't recall seeeing many setups this way with that small of a driven pulley--it's usually the other way around with the big pulley there, but I understand that you have to bump the speed up.

Hope this helps.
Ron

 

[Soundguy]

I would also be concerned about a smooth 2" pulley. Cogged would be better.. and chain would be great.

Soundguy

 

[getut]

I don't know why chain drive never occurred to me... that seems like a good way to go except for an 18" disk of spinning death (with teeth) kind of scares me. hehehe. /forums/images/graemlins/crazy.gif

I guess DIY projects are kind of fun until my family takes me to the hospital to extract an 18" sprocket from my sternum.

Sigh... maybe I'll go with the tiger power thing... will just have to park really far from the house and get a really long cord.

Getut