PTO generator at max torque or max HP?

[LouNY]

Amazing simply amazing I don't know how the various tractors I've had running PTO generators ever managed to work.
From way back when the Farmall 400 was running my fathers PTO generator for all the dairy farm loads from not much to almost maxing it out during feeding from the upright silos with the bulk tank compressors running to cool milk.
To putting a 7220 IH Magnum on my little 25 KW one day when my tractor acted up.
My old IH 350 utility ran good and stable, the Oliver 1550 never had a hiccup, the IH 574 will run fine and the Branson 8050 will run good stable power in the 540E mode.
Less then 2 Hz variance from no load to full load.
I'm not afraid to run my tractors on loads with no one present, if one goes down for some reason it would have sooner or later anyways.
The governors on all those tractors handled the varying loads just fine.
The only time I have had governors not be responsive enough was running a 540 generator on the 1000 rpm shaft at half throttle,
then the 574 didn't maintain the regulation I desired.
A 1086 did fine in that situation allong with the Magnums.

 

[CobyRupert]

Because of gearing TO the pto, the higher RPM will have more torque to the pto/generator to cover heavy loads.

SR

Yes, but....
… what if the engine’s torque curve drops off more at the higher rpm than the torque lost using the PTO gearing at lower engine rpm?
Doesn’t it now depend on the characteristics of the load being added? That is, the lower rpm engine only has to drop a few rpms for engine to recover with maximum torque, whereas the high rev engine will drop many more rpm, or dip for a longer period of time, to recover with less torque (because of where you’re at on torque curve)?
Sure, chances are a perfect storm won’t aligned like this, but….?

 

[Sawyer Rob]

The engine is making more HP at the higher rpm, so it holds its speed better at the higher rpm.

One of my tractors makes 60 hp at pto speed, but it makes 70 at max rpm, and that's on a dyno, not some book number.

SR

 

[npalen]

Seems like this discussion is ripe for someone to propose a frequency controlled governor retrofit.

 

[workinonit]

Tractor diesel governors are not like engine powered generators governors that control engine rpm to maintain a certain rpm and Hz cycles. Tractor diesel governors really only work at low or too high rpm. Ever mow sloped field? Rpm changes down and up hill. Can lower or increase throttle to maintain rpm but is not automatic or governored. You can maintain voltage and hertz pretty well and some loads like heaters and motors are tolerant to fluctuations. This does require some input from the operator. They do have a certain applications.

Stand alone generator generators can maintain clean power easily.

We have a 30+ year old Miller welder/generator gal/hr and 17 year old Yamaha 2400 watt inverter 1.75gal/8hr generator. Latter was run for 4 hours, refrigerator, freezer, lights, internet tv, wood stove fan and medical equipment last week. Our lifestyle and requirements make having back up power necessary.

There are many options and solutions.

This is just simply not true if the tractor is large enough for the load. And if diesels didn't control gens well, they wouldn't be so popular on standby gens. Here's the bottom line. There are a lot of you that for whatever reason don't like PTO generators. That's fine, but PTO gens work really well. In my opinion they are much better than standbys because I know my tractor will start, the standby you never know. Yes, it's not automatic but I really don't want it to be. I like to be there and know what's going on before I tie my gen to my houise load. It all boils down to the fact that it's an opinion and goodness knows, everyone has three of those.

 

[Smokeydog]

This is just simply not true if the tractor is large enough for the load. And if diesels didn't control gens well, they wouldn't be so popular on standby gens. Here's the bottom line. There are a lot of you that for whatever reason don't like PTO generators. That's fine, but PTO gens work really well. In my opinion they are much better than standbys because I know my tractor will start, the standby you never know. Yes, it's not automatic but I really don't want it to be. I like to be there and know what's going on before I tie my gen to my houise load. It all boils down to the fact that it's an opinion and goodness knows, everyone has three of those.

If pto generator works for you that’s great! Sized to a tractor and loads required. Worse is low hp tractors and small generators.

Diesel engine generator governors are different than what’s on tractors so your point is null.

Local sawmill uses 3phase diesel generator to power their mill. Owner was talking on looking for a replacement because of 15,000+ hours. 40Kw. Had another genset for a planer and resaw operation. I asked how about a pto generator? He had lots of tractors and existing fuel supply? He said we tried that, don’t work, can’t take the variable loads, burnt motors, ate fuel, it’s over there in the shed if you want it. Granted he was not your typical backup power user.

Pto generators have their place. Can get them at scrap prices at auctions around here. If they satisfy your need that’s great. I tend to now measure success in decades of use.

Sharing experiences helps us all. Your experience is valuable.

 

[LouNY]

I have to wonder how many of your portable or even whole house generators are 25 years old,
I know of several pto generators well over 20 years old and still in service.
As far as governors a tractor governor in good shape that hasn't had someone monkey with does a good job
holding constant rpm with a varying load.

To each his own, I like my pto generator and it has done an excellent job for me for well over 20 years.

 

[JethroB]

Seems like this discussion is ripe for someone to propose a frequency controlled governor retrofit.

Let’s add tractor water temp & oil pressure monitoring while we are at it.

 

[workinonit]

If pto generator works for you that’s great! Sized to a tractor and loads required. Worse is low hp tractors and small generators.

Diesel engine generator governors are different than what’s on tractors so your point is null.

Local sawmill uses 3phase diesel generator to power their mill. Owner was talking on looking for a replacement because of 15,000+ hours. 40Kw. Had another genset for a planer and resaw operation. I asked how about a pto generator? He had lots of tractors and existing fuel supply? He said we tried that, don’t work, can’t take the variable loads, burnt motors, ate fuel, it’s over there in the shed if you want it. Granted he was not your typical backup power user.

Pto generators have their place. Can get them at scrap prices at auctions around here. If they satisfy your need that’s great. I tend to now measure success in decades of use.

Sharing experiences helps us all. Your experience is valuable.

Funny how the best gen manufacturers make diesel gensets and they are preferred by most buyers. Experience, I've owned one since 1998 and used it for lots of things. It's mounted on a trailer that I hook behind my tractor and my welder and a small air compressor will fit on. I've run it behind 2 different JD tractors and both ran it flawlessly. The tractors control it to within 2 to 3 volts. Maybe the ones you are aware of aren't sized properly or are attached to tractors that don't control loads very well. I was stating my opinion but what you wrote was just simply not the truth based on my many hours of experience.

 

[California]

Lets not forget the OP was considering using a small tractor to run a PTO generator that is rated to need more horsepower than he has available, so limiting the load and the effectiveness of the tractor's governor are the major considerations in his application.