DIY PTO Generator

[3v0]

Soundguy I am leaning in favor of the PTO generator in that it is one less motor to maintain and with luck maybe a better head. The down side is that everything but my tractor is gas and I will need to keep additional disel fuel on hand for the tractor. But as others stated it keeps better then gas. I should check with the local truck stop to see if they have generator backup to pump fuel when there is a power out. But I would have to use the tractor to get there That is providing they are open. I guess they key here is to ration the use until one can ensure that one can get more fuel as suggested above.

What blows me away is the price of PTO shafts. It looks like another $200 or $300 and one still has to mount the generator.

 

[Dana Warner]

SurplusCenter.com has a good price on drive shafts.

 

[newbury]

<snip>
What blows me away is the price of PTO shafts. It looks like another $200 or $300 and one still has to mount the generator.

WOW! I hadn't priced them in a while. Glad my $600 12K Winco Generator came with it's PTO shaft!

 

[David Devuono]

Depending on the HP of the Tractor, but if I was building my own Generator, I am not sure I would be using 540\1000 PTO RPM to figure out the gear box or pully. Why run your tractor at 2500 RPM when it may easily run a generator at 1800 RPM. If you design it for the lower speed, you can ball park the gearbox and fine tune the motor speed to get 60HZ.

 

[joshuabardwell]

I've wondered about this. If the tractor is rated at a certain PTO HP, presumably that's at 540 RPM, no? If you have more HP than you need to generate the desired amount of power, then your point stands. But if you need full PTO HP, then wouldn't you need to run at full PTO RPM?

 

[Redneck in training]

Advantage of running at low speed is lower noise. The fuel consumption might be in fact higher at 1800 versus 2500 rpm. Check power, torque and specific fuel consumption curves of your engine on internet. You will see that the best fuel consumption is achieved at about PTO speed. The PTO speed is somewhat to the right (slightly higher speed) of the maximum torque. That is purposeful design. When you load the engine enough (in ex. 5 kW heater kicks in) that speed dips the torque increases and the engine is more resistant to bogging down. If you run at 1800 rpm and do the same, speed will dip much more because as you slow down torque also gets lower.
Higher speed might have only marginally higher engine wear. I doubt that you would see any difference in life of the tractor. Tractor engines are so derated they last forever even at full speed.

 

[chim]

WOW! I hadn't priced them in a while. Glad my $600 12K Winco Generator came with it's PTO shaft!

Good chance you won't need the shaft on a finish mower in the middle of a blizzard or hurricane. Borrow one if the length works out. I built a "Binford" style leaf blower and use the shaft from one of my RFM's. I didn't want to buy a shaft for something non-essential that would run 2 hours per year.

 

[Soundguy]

I've heard this point made before--that having a diesel genset is an advantage because gas quickly sells out, but diesel is in much less demand.

I can't for the life of me figure out why all gas stations don't supply themselves with a backup generator to run the pumps during a power outage. It's not like they won't have the fuel to run them!

makes ya wonder don't it...

 

[David Devuono]

Advantage of running at low speed is lower noise. The fuel consumption might be in fact higher at 1800 versus 2500 rpm. Check power, torque and specific fuel consumption curves of your engine on internet. You will see that the best fuel consumption is achieved at about PTO speed. The PTO speed is somewhat to the right (slightly higher speed) of the maximum torque. That is purposeful design. When you load the engine enough (in ex. 5 kW heater kicks in) that speed dips the torque increases and the engine is more resistant to bogging down. If you run at 1800 rpm and do the same, speed will dip much more because as you slow down torque also gets lower.
Higher speed might have only marginally higher engine wear. I doubt that you would see any difference in life of the tractor. Tractor engines are so derated they last forever even at full speed.

My point is, if you have a 50 HP tractor running a 10K generator, operating at 1800 RPM, it is not going to bog down the tractor. If you have a 15 K generator on a 20 HP tractor, you are going to want to design it to run at max speed.

 

[R W]

Perhaps you may be able to tell us what you mean by the above words.

I have built and have seen a lot of home built machines etc, most of which were well constructed.