PTO Generator on L185

[L185 Owner]

Hello All:

Not sure if this goes here or in the implements thread. I will try to tailor this to the operating part. I have a L185. Its a great machine, rated a 17 hp and 14 pto hp. I am considering a winco PTO generator. I know the math 2 hp = 1 kw. I know if i bought a 15kw according to the stated specs id only get 7kw out of the generator. I can make that work with the house loads i would be looking at.

The PTO generator asks for 540/515 pto rpm. My tractor has 3 pto speeds. Based on the pto specs (540@2430, 702@2430, and 1000@2430) it looks like it could run the machine at a very modest RPM in PTO2 or PTO3 and obtain the 540/515 required rpm. If i cross multiply I should be around 1870 or 1315. I couldn't imagine that little tractor complains about running at that speed for hours or days!! Any concerns here??

Am i looking at the math and setup the correct way? Has anyone here done this with one of these machines? Mine cranks like a champ, seems dependable as can be, and I DON'T NEED IT FOR STORM CLEAN UP!! It seems like a very viable option. Curious if others have done this with older kubota's - L175 or L185 or smaller ones? I also think these machines are stronger than they are rated for i wouldn't be surprised if I got more out of it than what the sticker suggests. Any experience on that?

Thank YOU for your help on these questions.

 

[85Hokie]

Hello All:

Not sure if this goes here or in the implements thread. I will try to tailor this to the operating part. I have a L185. Its a great machine, rated a 17 hp and 14 pto hp. I am considering a winco PTO generator. I know the math 2 hp = 1 kw. I know if i bought a 15kw according to the stated specs id only get 7kw out of the generator. I can make that work with the house loads i would be looking at.

The PTO generator asks for 540/515 pto rpm. My tractor has 3 pto speeds. Based on the pto specs (540@2430, 702@2430, and 1000@2430) it looks like it could run the machine at a very modest RPM in PTO2 or PTO3 and obtain the 540/515 required rpm. If i cross multiply I should be around 1870 or 1315. I couldn't imagine that little tractor complains about running at that speed for hours or days!! Any concerns here??

Am i looking at the math and setup the correct way? Has anyone here done this with one of these machines? Mine cranks like a champ, seems dependable as can be, and I DON'T NEED IT FOR STORM CLEAN UP!! It seems like a very viable option. Curious if others have done this with older kubota's - L175 or L185 or smaller ones? I also think these machines are stronger than they are rated for i wouldn't be surprised if I got more out of it than what the sticker suggests. Any experience on that?

Thank YOU for your help on these questions.

In my opinion it might be best to run this in the 540 pto gear, reason I say this is simply the torque that will be needed, if a generator is running with no load, almost any situation will work - BUT once you place a load on it the game changes! Looking at the specs - it does say to get full capacity 30 HP is needed. But then again yours will produce "X" amps and at any current RPM. Might want to experiment with so items, for example, get the genny installed and then plug in a circular saw and a hair dryer any anything you can find handy that will pull a high rate of amps when started and see how the tractor performs.

Looking at the last PTO option... option 3

if you run 1000 rpms @ 2430 ..... and basic math says 540 rpm is about 1312 RPMs ....... looking at the torque curve, the 2400 ish is where the "sweet" spot is located. SO this should not be a good idea, unless you are running a series of LED lights only!

 

[Sammy3700]

What I have is a 12kw which is 24pto hp at max output and run it with a L3800 which is 30pto also my neighbor has same generator with a B3200 which is 24pto both tractors do good however you can hear the tractor “load up“ as you increase the load on the generator. I know I didn’t answer your question so yes just be careful with the electrical load.

 

[L185 Owner]

In my opinion it might be best to run this in the 540 pto gear, reason I say this is simply the torque that will be needed, if a generator is running with no load, almost any situation will work - BUT once you place a load on it the game changes! Looking at the specs - it does say to get full capacity 30 HP is needed. But then again yours will produce "X" amps and at any current RPM. Might want to experiment with so items, for example, get the genny installed and then plug in a circular saw and a hair dryer any anything you can find handy that will pull a high rate of amps when started and see how the tractor performs.

Looking at the last PTO option... option 3

if you run 1000 rpms @ 2430 ..... and basic math says 540 rpm is about 1312 RPMs ....... looking at the torque curve, the 2400 ish is where the "sweet" spot is located. SO this should not be a good idea, unless you are running a series of LED lights only!

So the 540 PTO RPM @ 1315 Engine RPM (PTO3) may be a false sense of power in that it may not actually have the torque to push a 15 amp load - let alone the 29/30 amp the tractor should push? I have never hooked it up to a PTO generator so no experience there. I was hoping to keep the engine RPM lower (quieter) if i were to run it for 12 or 24 hours and still get the benefit of the full 30 amps the tractor should push. Has anyone tried the higher PTO gear and lower engine RPM and seen how the machine reacts to a load? I have done it on a bush hog - does fine until the grass it too thick, and it bogs down. I assume a generator is the same - just dont know. I also know that a generator hook up is stationary - bush hogging is traveling and variable length and height with each pass.

 

[Dave_eng]

So the 540 PTO RPM @ 1315 Engine RPM (PTO3) may be a false sense of power in that it may not actually have the torque to push a 15 amp load - let alone the 29/30 amp the tractor should push? I have never hooked it up to a PTO generator so no experience there. I was hoping to keep the engine RPM lower (quieter) if i were to run it for 12 or 24 hours and still get the benefit of the full 30 amps the tractor should push. Has anyone tried the higher PTO gear and lower engine RPM and seen how the machine reacts to a load? I have done it on a bush hog - does fine until the grass it too thick, and it bogs down. I assume a generator is the same - just dont know. I also know that a generator hook up is stationary - bush hogging is traveling and variable length and height with each pass.

This subject comes up so often I have saved the following explanation:

The torque curve below is not for your particular engine but diesels have the same shaped curves.

For satisfactory generator operation, the engine needs to be running on the downward slope of its torque curve so that if it slows slightly under load the available torque is increasing. This is the area shown with the YELLOW arrow.

Starting to try


Starting to try and run the engine slower means you may be at a point on its torque curve where the torque falls off as rpm's decrease which can lead to a sudden stall.

I apologize for resorting to technical jargon to make a point but it is critical in generator operations.

The torque curve shows a downward slope as it goes from 2,800 to 3,600 rpm.

If you have the engine rpm's in that range and the load on the generator increases as the engine starts to slow down from its 3,600 rpm needed to produce 60 cycle AC, the torque output of the engine increases so it accepts the extra load without any fuss.

By utilizing a higher pto speed so as to need lower engine rpms' to turn the generator head at 3,600 rpm, you are now operating on a place on the engine torque curve where a slight lowering of engine rpm produces less torque and this situation quickly deteriorates into the engine stalling.

Big tractors now come with an ePTO option (economy pto) which provides the ability to achieve 540 pto speed at lower engine rpm's This is possible when the engine has more than enough torque to power an implement.

John Deere offers this feature but also highlights a caution:

When to use 540 economy mode?
540 economy is ideal for many applications including mowing, baling, or tilling. The 540 economy setting cannot be used with full advertised PTO horsepower (hp). If full PTO hp is required, the tractor should be run in standard 540 mode.

Dave

 

[L185 Owner]

This subject comes up so often I have saved the following explanation:

The torque curve below is not for your particular engine but diesels have the same shaped curves.

For satisfactory generator operation, the engine needs to be running on the downward slope of its torque curve so that if it slows slightly under load the available torque is increasing. This is the area shown with the YELLOW arrow.

View attachment 48403 Starting to try


Starting to try and run the engine slower means you may be at a point on its torque curve where the torque falls off as rpm's decrease which can lead to a sudden stall.

I apologize for resorting to technical jargon to make a point but it is critical in generator operations.

The torque curve shows a downward slope as it goes from 2,800 to 3,600 rpm.

If you have the engine rpm's in that range and the load on the generator increases as the engine starts to slow down from its 3,600 rpm needed to produce 60 cycle AC, the torque output of the engine increases so it accepts the extra load without any fuss.

By utilizing a higher pto speed so as to need lower engine rpms' to turn the generator head at 3,600 rpm, you are now operating on a place on the engine torque curve where a slight lowering of engine rpm produces less torque and this situation quickly deteriorates into the engine stalling.

Big tractors now come with an ePTO option (economy pto) which provides the ability to achieve 540 pto speed at lower engine rpm's This is possible when the engine has more than enough torque to power an implement.

John Deere offers this feature but also highlights a caution:

When to use 540 economy mode?
540 economy is ideal for many applications including mowing, baling, or tilling. The 540 economy setting cannot be used with full advertised PTO horsepower (hp). If full PTO hp is required, the tractor should be run in standard 540 mode.

Dave

Thank You Dave - I think that sums it up. The higher PTO gears don't allow you to develop full torque. Your graph and explanation hit it on the head - underdeveloped torque you slide to 0 and a stall. Conversely over developed you back slide to the peak of the curve. All that said - looks like i will have to be in the 2600+ rpm range in PTO1 (2430 = 540 in PTO1 for my model) to get the full output ability of the tractor and be in an over developed torque range. I suppose I have a choice to make. I have been debating on a MEP 802a or MEP 803A or a Winco 15kw. My machine will only produce 7kw +/- based on stickered ratings. My thinking was low RPM and still get full power, does not look to be the case!! Decisions Decisions!!!

Does anyone know where to find the torque curve for the L185 like the one above?

 

[85Hokie]

If you find one - it will show the highest torque right around the 540 PTO setting..... since there is always a little more RPM left above that setting but torque is dropping off, this in theory is the sweet spot of torque - so in your case, the chart would be something in the range of 2400-2500 rpms.

Most all diesel have a similar spot - the change occurs with top RPM settings.... some top out at 2600 and other engines top out at 3600 rpms..... so the torque curve will move according to the range of total RPM.

 

[SidecarFlip]

Irregardless of what genny you put on ANY tractor, moat all are 2 pole units and must spin at 3600 rpm (via an installed gearbox) to attain output at 60 hz.). Consequently, loading of the generator will drop the armature speed and the genny won't be able to produce 60 hz current. Current output below 60 hz will adversely impact any motor driven appliance and can cause them to fail, especially refrigeration equipment and electronic equipment that rely on 60 hz for operation.

Most generator heads (Winco included) depend on a constant 3600 rpm speed to attain the correct cps. I would suggest, if you plan on getting any pto driven unit, to invest in a cps meter.

 

[Dave_eng]

I looked at a lot of torque curves today looking for your V1501 82 mm stroke engine with no luck.

What was very apparent was that all the non turbo engines has almost identical torque curves.

The actual numbers (Torque, HP) would vary between different engines depending upon the total displacement yet the curve shapes were the same.

Dave

 

[L185 Owner]

I looked at a lot of torque curves today looking for your V1501 82 mm stroke engine with no luck.

What was very apparent was that all the non turbo engines has almost identical torque curves.

The actual numbers (Torque, HP) would vary between different engines depending upon the total displacement yet the curve shapes were the same.

Dave

My L185 has a Z751A - believe it is a 2 Cylinder Diesel. Loud but proud!!

 

[Russell King]

And 2 HP = 1.49 kW so you may get a few more watts output than your calculations show currently.

 

[GreensvilleJay]

re: I was hoping to keep the engine RPM lower (quieter)

I know of someone who added a couple 'extra' muffers inline to his tractor/genny setup. We could stand next to it,watch the PTO spin and talk as if tractor wasn't running !

 

[SidecarFlip]

re: I was hoping to keep the engine RPM lower (quieter)

I know of someone who added a couple 'extra' muffers inline to his tractor/genny setup. We could stand next to it,watch the PTO spin and talk as if tractor wasn't running !

Lower engine rpm equates to lower PTO rpm and that equates to lower cycles per second (hertz) which equates to issues with any motorized device connected to the auxiliary generator. Any pto genny will have to run at either 3600 rpm armature speed or 1600 rpm armature speed, depending on how the armature is wound (2 pole or 4 pole) and like I said above (that you need to understand), most pro genny's are 2 pole.

Consequently, they need to operate at 540 pto rpm shaft speed to achieve the correct armature speed. PTO genny's will all have married gearboxes to achieve the correct speed but, irregardless of that, the INPUT RPM MUST BE 540 (or 1000 rpm) if the unit is rated for a 1000 rpm pto.

There is NO EXCEPTIONS to that.

If you run at a lower speed, the cycles per second will be lower, and less that 60 cps, like I said, will potentially fry your motorized devices and will adversely impact your electronic devices as well.

Running at a reduce tractor rpm may be quieter but it basically won't work. well it will for a while, until you cook your devices.,

 

[Dave_eng]

And 2 HP = 1.49 kW so you may get a few more watts output than your calculations show currently.

Lower engine rpm equates to lower PTO rpm and that equates to lower cycles per second (hertz) which equates to issues with any motorized device connected to the auxiliary generator. Any pto genny will have to run at either 3600 rpm armature speed or 1600 rpm armature speed, depending on how the armature is wound (2 pole or 4 pole) and like I said above (that you need to understand), most pro genny's are 2 pole.

Consequently, they need to operate at 540 pto rpm shaft speed to achieve the correct armature speed. PTO genny's will all have married gearboxes to achieve the correct speed but, irregardless of that, the INPUT RPM MUST BE 540 (or 1000 rpm) if the unit is rated for a 1000 rpm pto.

There is NO EXCEPTIONS to that.

If you run at a lower speed, the cycles per second will be lower, and less that 60 cps, like I said, will potentially fry your motorized devices and will adversely impact your electronic devices as well.

Running at a reduce tractor rpm may be quieter but it basically won't work. well it will for a while, until you cook your devices.,

The owners question had to do with his tractor having a 3 speed pto, so his plan was to operate above the lowest gear pto speed in order to still achieve an actual 540 rpm at the pto with lower engine rpm's

He said: My tractor has 3 pto speeds. Based on the pto specs (540@2430, 702@2430, and 1000@2430)

Dave

 

[SidecarFlip]

The owners question had to do with his tractor having a 3 speed pto, so his plan was to operate above the lowest gear pto speed in order to still achieve an actual 540 rpm at the pto with lower engine rpm's

He said: My tractor has 3 pto speeds. Based on the pto specs (540@2430, 702@2430, and 1000@2430)

Dave

Didn't catch that Dave, I missed that part. What I am understanding from the OP is (and not meant as an insult), but he has a smaller tractor (I always get flack over that statement...lol) and to expect a lower output tractor to deliver sustainable current for a home is folly because the motor won't be able to handle any sizeable pto genny's input power requirements at a reasonable sustained load @60hz continuous.

I have a 26KW standby genset with a JD Diesel engine and it works hard at 26 KW. and I'm very careful not to overload it because pushing it past design limits will decrease armature speed (mine is a 4 pole) and the result is a drop in cps and voltage. One needs to understand that output current (and Hertz) is directly related to input horsepower (and torque rise). Consequently, the smaller the tractor, the smaller the output current wise is and maintaining a 60 cps frequency can be an issue.

I could have very well went with a big Winco and ran it off of one of the tractors but in the interests of convenience and ease of operation (I'd never in my wildest dreams expect my wife to get a tractor out of the barn, hook up a pto genny and plug it into a transfer switch in the midst of a storm, because that is when you loose utility power), so I went with a stationary standby unit. Mine runs automatically and assumes the load in 30 seconds after starting and when the utility power resumes, drops out in 15 seconds and it does an 'exercise' run weekly. It is plumbed into my 1000 gallon bulk tank so long as I keep fuel in the tank, it's all good.

 

[Dave_eng]

Didn't catch that Dave, I missed that part. What I am understanding from the OP is (and not meant as an insult), but he has a smaller tractor (I always get flack over that statement...lol) and to expect a lower output tractor to deliver sustainable current for a home is folly because the motor won't be able to handle any sizeable pto genny's input power requirements at a reasonable sustained load @60hz continuous.

I have a 26KW standby genset with a JD Diesel engine and it works hard at 26 KW. and I'm very careful not to overload it because pushing it past design limits will decrease armature speed (mine is a 4 pole) and the result is a drop in cps and voltage. One needs to understand that output current (and Hertz) is directly related to input horsepower (and torque rise). Consequently, the smaller the tractor, the smaller the output current wise is and maintaining a 60 cps frequency can be an issue.

I could have very well went with a big Winco and ran it off of one of the tractors but in the interests of convenience and ease of operation (I'd never in my wildest dreams expect my wife to get a tractor out of the barn, hook up a pto genny and plug it into a transfer switch in the midst of a storm, because that is when you loose utility power), so I went with a stationary standby unit. Mine runs automatically and assumes the load in 30 seconds after starting and when the utility power resumes, drops out in 15 seconds and it does an 'exercise' run weekly. It is plumbed into my 1000 gallon bulk tank so long as I keep fuel in the tank, it's all good.

Agreed

I went with a 22 KW Generac on propane for convenience.

After all if your nearest neighbor is too far away to run an extension cord from your unit, at some point too much capacity just means extra operating costs

The following shows how under utilizing a generator just makes it more inefficient. 27.0% efficient at full load and dropping to 19.9% efficient at 25% of rated capacity.

Dave

 

[L185 Owner]

I want to thank everyone so far for all their help on this. The torque curve really sums it up. The tractor can produce power but there is a limit and I can’t get cute with pto3 and low Engine rpms and think I have the torque developed to start big loads or the well!! So, point taken, I can experiment on my own and see how she does, but at the end of the day I can manage those realities and in a real situation have the knowledge needed to go forward.

That said my next real question is do any of the L185 owners out there or owners of older Kubotas feel comfortable running their machine at 2430 - pto1 or 1850/1900 pto2 maybe at night and low loads for possibly 24 or 72 hours straight?

Let me say - I am not worried about the hours. I’m not worried about wear and tear. We have it to use it! I know that Diesel engines can run and run and run - I just wonder about it being old and standing up to that test. I mean I am cautiously optimistic that the 1974 engine and radiator and pistons can tough it out. But does anyone have any experience with an older Kubota or tractor doing it? I can see on YouTube some old ones doing it - just wondering if it’s realistic to ask it to push its 7kw or so at 2430 rpms for worse case 5 days???!!! What level of confidence would you have that your older Kubota or other brand would answer the call??

 

[85Hokie]

I want to thank everyone so far for all their help on this. The torque curve really sums it up. The tractor can produce power but there is a limit and I can’t get cute with pto3 and low Engine rpms and think I have the torque developed to start big loads or the well!! So, point taken, I can experiment on my own and see how she does, but at the end of the day I can manage those realities and in a real situation have the knowledge needed to go forward.

That said my next real question is do any of the L185 owners out there or owners of older Kubotas feel comfortable running their machine at 2430 - pto1 or 1850/1900 pto2 maybe at night and low loads for possibly 24 or 72 hours straight?

Let me say - I am not worried about the hours. I’m not worried about wear and tear. We have it to use it! I know that Diesel engines can run and run and run - I just wonder about it being old and standing up to that test. I mean I am cautiously optimistic that the 1974 engine and radiator and pistons can tough it out. But does anyone have any experience with an older Kubota or tractor doing it? I can see on YouTube some old ones doing it - just wondering if it’s realistic to ask it to push its 7kw or so at 2430 rpms for worse case 5 days???!!! What level of confidence would you have that your older Kubota or other brand would answer the call??

The real side of this coin is ..... a tractor PTO generator is fine and dandy, but once hooked, you no longer have the tractor to do work with.... and yes your machine will run as long as you wish it too..... just keep adding fuel!

And have you thought about gallons per hour rate of fuel consumption?

a propane or gas generator that is separate will have plenty of power to do the job and it is portable to boot, and in the short and long run - will be less to buy and maintain.

If you think about it, most houses are only using about 30 some amps at any given single time - now true, a well pump kicks on, wife has stove on with burners, and someone is using the microwave all at the same time it will get above that 30 amp figure - but most other times a 7,500 watt generator will do the job and be portable also. And the cost of one of these is under $750, true you have to buy gas and treat it and keep a good bit on hand or several propane tanks.

I bought a used Craftsman generator last month, brand new it cost $460 plus tax...... bought it for $250 with 4 hours on the meter and have had to use it once already..... ran for 10 hours keeping a fridge and lights on without filling back up.

 

[SidecarFlip]

Interestingly, Mine is a Generac but the engine is a JD Diesel. I entertained a large Winco a while back (have plenty of power to run a big one) but the standby won out, not only for convenience but I don't have to constantly add fuel and increase the maintenance intervals on the tractors either.

More than just adding fuel on a long run situation with a tractor. You have to keep an eye on stuff like coolant and lube oil too. My standby has automatic shutdown for low coolant level and low lube oil level. A tractor don't and my standby turns at 1800 rpm (4 pole head) so it's not screaming away for hours on end.

if I remember correctly my diesel was around 7 grand when I bought it but I did have to have a qualified electrician hook it up (electricity isn't a strong point with me) and it has a fully automatic vacuum breaker transfer switch so it will assume the entire load with no ramping up.

 

[torch]

There is a very good study by Ontario Ministry of Agriculture on the use and set-up of PTO powered generators available here:

Page Not Found | Ministry of Food, Agriculture, and Rural Affairs

It addresses your specific question near the end.

Short summary: following a long term power outage (ice storm), many farms burned out motors, etc. running on PTO generators. It's not all about available wattage and horsepower. Frequency and voltage are critical and depend on RPM.

Running the PTO in high gear a low engine rpm magnifies frequency and voltage fluctuations. Even a modern tractor with "economy" setting produced unacceptable variations.