PTO HP in different ranges.

[F15DOWNER]

Hi
I just purchased a generator head that I would like to run with my tractor. The gen head needs to turn at 1800 RPM. Does it make a difference in PTO HP within the 3 ranges?
I don't want to set it up at a 2:1 ratio in range 2 and not have enough power to run it.

Question 2
At what Engine RPM do you reach the rated PTO speed?

Thanks
Tom

 

[Mickey_Fx]

Sure would have helped if you had given some important info. What size generator? What model tractor?

Generator size will determine how much power is needed to produce full A.C. power. Tractor model number will tell us how much power you have available and potentially what PTO gear range you need to produce adequate power and adequate speed.

 

[SATOHBULL]

The HP is the same at all speeds. HP is just torque applied over time. As the speed increases the torque will decrease but HP stays the same. Well, there might be some frictional loses, but not much.

All the compact diesels I've looked at develop rated pto speeds between 2000 and 2600 RPM. As the earlier responder mentioned, with your tractor info you can get a much more accurate answer.

 

[roxynoodle]

His user name says FX15D owner. On my 1510 first speed on the PTO generates 540 at 2200 rpm. On speed 2 it generates 1000 at the PTO. My owner's manual says that the third PTO speed will be whatever the engine speed is (must be a straight 1:1 gear ratio). So based on that I would think use 3rd speed on the PTO and set engine throttle at 1800rpm? I don't know that your PTO is set up the same as mine though.

 

[Tom_Veatch]

...
So based on that I would think use 3rd speed on the PTO and set engine throttle at 1800rpm? I don't know that your PTO is set up the same as mine though.

Those PTO speeds match what's stated in the manual for my 2220D and occur at about 2250 engine rpm.

If F15DOWNER is going to direct drive the generator head, the 3rd Range 1800 RPM option is probably the best, if not the only, option. To get 1800 at the PTO in either 1st or 2nd PTO Range, the engine would have to be run well above redline. He could also get there in Range 4, if he has it, which, according to my manual, is "slightly overdrive".

But, there is the question of power available at the 1800 RPM speed. The engine develops peak power at a specific rpm. The power developed at any other speed will be less. I suspect that the PTO gearing is designed (or should be) to run the PTO at it's standard rpm (540, 1000, etc.) with the engine at, or near, it's peak power RPM. Running at 1800 RPM may reduce the amount of power available below what F15DOWNER is expecting.

My recommendation would be to insert step-up gearing ahead of the gen head and step the PTO rpm up from either 540 or 1000 to the needed 1800 at the generator. Then he could run the tractor at the (assumed) best power RPM of the tractor and get the speed he needs at the generator with the maximum available power.

 

[F15DOWNER]

Sorry for the confusion. The model is F15D which is around 18HP according to Hoye's web site, which I have great confidence is right.
The generator is a 10K.
My PTO is three speed, 600, 916, 1200 roughly
My plan was not to run it direct, but a 2:1 or 3:1 or something in between, ratio depending on the outcome of this conversation.

After hearing what I have so far I think I will run 916 PTO speed and select a ratio that will give me 1800 RPM at about 2200 engine RPM which should be real close to 2:1.

I know that 10K is pushing it on HP, that is why I'm doing my homework, with the people that I am very confident that know.

I would rather have a generator that runs under the rated output with this tractor so when I upgrade the tractor sometime in the future it will be just right. (hopefully soon)

Thanks for the reply's so far and if anybody else has any input I will be very grateful.

Where are you soundguy? I always look forward to your input.

Thanks again
Tom

 

[Tom_Veatch]

...
After hearing what I have so far I think I will run 916 PTO speed and select a ratio that will give me 1800 RPM at about 2200 engine RPM which should be real close to 2:1.
...

Sounds like a plan to me. Should get you real close, and you can fine tune operating speeds using the generator meter(s) and the tractor throttle.

The "book" says about 1/2 KW per HP. That's a rule of thumb to take into account inefficiences in converting the tractor power to electrical power. Depending on the efficiencies (or lack thereof) in your particular setup you may do better than that - or you may do worse. But I don't think an 18 PTO HP tractor is terribly mismatched to a 10KVA generator. If you find it bogging your tractor down, you can always turn off a light or two, sequence or schedule the loads, etc.

 

[kenmac]

Is your genset 10k running or surge ? the rule of thumb is 2 engine hp per gen kw.so you'er close on engine hp. Just my opinion but, I think hp still makes a difference even with 3 ranges. When you start to load the gen is when you will need the hp.I think you will do ok you'er only 2 hp off .Not ideal but, should work.

 

[Cord]

If he uses a belt drive, he'll proably loose more than 2hp in it. My pto tops out at 1200rpm, so if he can truly hit 1800 in high, then that would be his most efficient speed.

 

[normde2001]

Sorry for the confusion. The model is F15D which is around 18HP according to Hoye's web site, which I have great confidence is right.
The generator is a 10K.
My PTO is three speed, 600, 916, 1200 roughly
My plan was not to run it direct, but a 2:1 or 3:1 or something in between, ratio depending on the outcome of this conversation.

After hearing what I have so far I think I will run 916 PTO speed and select a ratio that will give me 1800 RPM at about 2200 engine RPM which should be real close to 2:1.

I know that 10K is pushing it on HP, that is why I'm doing my homework, with the people that I am very confident that know.

I would rather have a generator that runs under the rated output with this tractor so when I upgrade the tractor sometime in the future it will be just right. (hopefully soon)

Thanks for the reply's so far and if anybody else has any input I will be very grateful.

Where are you soundguy? I always look forward to your input.

Thanks again
Tom

You will only have pto, (15), hp available to run the generator, giving an effective 7.5kw. If it's just a bare head, connection and gearing should be a real challenge.