Tractor PTO driven generator ?

[MoreWellie]

@ that monies what have you got to loose ?

As it looks to be 415v output then I guess most of the electronic stuff in his house

 

[Matchless]

Ok, I am not well up on electrickery, the genny seems to be geared, looks like a chain drive under a cover, input could easily be 800 rpm to get 1500 at the genny shaft, has a 240v socket as well as the three phase, what do I want run off it, house, not that small a house! not so worried about workshop if only a short power cut but the power situation looks a bit sketchy this winter, especially if the pint size Napoleon finds some more toys to chuck out of his pram, I actually have three phase (for shed) house runs from one of the phases, I am not wanting a Chinese pos that dies before I need it, but would like to run the whole house including oven and hob, fridge, freezer, etc. etc. in case of day long power cuts, 10kva? ex hire Stephill? overkill? live in hope?

 

[Bornfree]

That's going to make an extremely unbalanced load for a small 3ph generator. If you need 3ph You will need a larger generator if not get a single phase one and just run the house.

 

[GRW]

Ok, I am not well up on electrickery, the genny seems to be geared, looks like a chain drive under a cover, input could easily be 800 rpm to get 1500 at the genny shaft, has a 240v socket as well as the three phase, what do I want run off it, house, not that small a house! not so worried about workshop if only a short power cut but the power situation looks a bit sketchy this winter, especially if the pint size Napoleon finds some more toys to chuck out of his pram, I actually have three phase (for shed) house runs from one of the phases, I am not wanting a Chinese pos that dies before I need it, but would like to run the whole house including oven and hob, fridge, freezer, etc. etc. in case of day long power cuts, 10kva? ex hire Stephill? overkill? live in hope?

If you want to run ovens and stuff - they take big power and you'll need a big genny.
If you are happy to spend a few grand, then happy days.
Stephill do some cracking multi-phase Gensets that have a big multi-deck rotary switch in the build, so you can reconfig the set from 3ph to 1ph (proper, not just off 1ph, but fully switched). Not cheap, but using Kubota, Isuzu engines and decent build for the Rental market. Something like their 16, 20 or 25 kva multi-phase sets would probably do what you need on the workshop or the house.

Probably serious overkill for most though, for short-term utility interruptions.
If you're prepared to compromise, you can get away with a couple of lights, the telly, fridge, freezer and the ch controls with maybe 3kva-5kva - and get a camping gas stove for a few quid to heat food and make hot drinks.
Most can do without the oven and the white goods for a day, & save a bundle over a big genny.

Put a proper changeover switch into your Electrical distribution and you can have your limited small genny power anywhere on your property (within it's power capacity of course) - so you don't need to rough it too much.

You pays yer money & takes yer choice

 

[julianthegypsy]

Just a note on PTO drives. Both six spline 540rpm and 21 spline 1000rpm are standard tractor outputs. The difference is that 540 is used on smaller tractors, up to about 90-100hp, and 1000 on anything bigger. It's done that way to reduce the torque loads through the transmission on higher horse tractors, and machines designed for either will be geared accordingly. You can't take something designed for 540 and run it at 1000. Well, you can, if you want to see things come apart. This is a frequent disaster with pto driven saw benches when the blade shatters. Likewise, if you take something designed for 1000 and run it at 540, things will also break.
Tractors have a mark on the rev counter corresponding to pto speed, typically about 3/4 of the way up between max torque rpm and max power rpm, so the engine should be rock solid, not revving its nuts off and not dipping when you hit it with some load. These things are designed the way they are for good reason, it's best not to muck about with them!

 

[Bornfree]

4 speed is the normal on modern tractors. 540/1000 and economy in both.

 

[Geoffm]

I have been looking at PTO generators for backing up,the cowshed for power cuts.they take a good amount of power.
If you have the space, you can often get second hand generators cheaply that have been removed from buildings where they were used as backup power. They only ran under the monthly test for 20 or 30,years then removed.
It would be cheaper than making this fit an engine unless you have a tractor.myou engine will be to small under load. For the output of the engine, you can buy a petrol or small diesel generator. The same size, plug and go with voltage regulation.
I have a 2.2 kva Honda generator. It has been reliable and starts every time and fine for power tools, but useless for sensitive electronics. I tried running the office on it, but the UPS had a fit due to the dirty power.

 

[Munkul]

For the record, a lot of farmers have 6 spline PTOs on everything, regardless of what speed its supposed to be ran at

 

[8ob]

Lots of power sapping transfer gears going on with a tractor pto, on 540 the tractors output has already gone through a gear reduction and then the pto generator hops it back up again with another gear set. Far better to direct drive a genny off a decent governed stationary engine. Did the same thing for a mates Stenner sawmill, he had a 60k tractor tied up running this monster so I fitted a perkins to it and he sold the tractor.

Bob

 

[Fraserb]

For the record, a lot of farmers have 6 spline PTOs on everything, regardless of what speed its supposed to be ran at

We only have 3 machines that aren't 6 spline shafts, 1 of the power harrows, straw grinder and the big baler is on the big 20 spline shaft. With selectable pto speeds you can run the machine at 1000 rpm when using the 6 spline shaft.

Our generator makes anything less than 180hp struggle.

 

[Munkul]

I think the 6 spline shaft is likely to be twisted if 150+HP is run through it? The PTO output shaft is generally limited to the machine being powered?

This is an argument that has been had many many times on farming forums
The general consensus is (and i agree with them), that 21 splines don't handle torque any better than 6 splines - as the shaft diameter is practically the same.

The reality is, that 1000rpm almost halves the torque for the same power transmission, compared to 540rpm. And given that you can put 300hp through a 1000rpm 21 spline, you've got a lot of leeway on smaller tractors like ours to use 6 spline on everything I think TBH we only have one true 1000rpm machine now, the power harrow, but we run it on a 110hp tractor.

Oh, and front linkage PTOs are generally 1000rpm and 6 spline - factory spec. Generally not rated above 180hp but that's as much to do with the design of propshafts, small clutches and gearboxes (and not overloading the front end of a crank)

@Fraserb 180hp genny, that's a big boy

 

[oilcooled :)]

The bottom line is if you own a decent tractor and u don’t mind coupling it up to a pto generator, then there a good cheap way of generating power,
And if you don’t own a tractor forget about it and just buy a generator

 

[GRW]

As the recent posts point out - while a PTO Gen can theoretically be used as a primary power supply - that does not mean it's a good idea.
It isn't.
The efficiency is poor (due to the drivetrain sapping energy and the tractor thundering away etc).
They are a cheap way to get big power as you basically provide your own engine and over the years I've sold a heck of a lot of them.... for Standby.
I would never ever say that they are suitable for prime duty. That is what Diesel Generators are for

 

[Fraserb]

This is an argument that has been had many many times on farming forums
The general consensus is (and i agree with them), that 21 splines don't handle torque any better than 6 splines - as the shaft diameter is practically the same.

The reality is, that 1000rpm almost halves the torque for the same power transmission, compared to 540rpm. And given that you can put 300hp through a 1000rpm 21 spline, you've got a lot of leeway on smaller tractors like ours to use 6 spline on everything I think TBH we only have one true 1000rpm machine now, the power harrow, but we run it on a 110hp tractor.

I'd maybe have a rethink if we were running 200hp+ PTO equipment like Fraser, though!

@Fraserb 180hp genny, that's a big boy

We've only screwed one pto shaft on a tractor and that was a 21 spline one, our newest power Harrow came with a 6 spline shaft but runs at 1000 rpm

I can't remember the output of the genny, the smaller tractors can run it if we don't switch everything on, when it's on tbe 250hp tractor it usually sits at 80% engine load when there's a lot of things running.

 

[GRW]

We've only screwed one pto shaft on a tractor and that was a 21 spline one, our newest power Harrow came with a 6 spline shaft but runs at 1000 rpm

I can't remember the output of the genny, the smaller tractors can run it if we don't switch everything on, when it's on tbe 250hp tractor it usually sits at 80% engine load when there's a lot of things running.

That's a BIG PTO Genny (That is working hard) if it's drawing about 200Hp. Probably over 100kva.
The biggest alternator frame size we can couple to the biggest, highest rated gearbox is about 110kva - so you're right at the top-end.
Once you get up at these power levels, and consider that you need to take perhaps a £200k tractor off the jobs it was bought for to run the genny - I tend to at least suggest to a Farmer that a dedicated Diesel Generator is worth considering, but the final choice is of course the clients

 

[anto44]

We've only screwed one pto shaft on a tractor and that was a 21 spline one, our newest power Harrow came with a 6 spline shaft but runs at 1000 rpm

I can't remember the output of the genny, the smaller tractors can run it if we don't switch everything on, when it's on tbe 250hp tractor it usually sits at 80% engine load when there's a lot of things running.

It'd be interesting to see how the fuel cost per hour running that output compares between the tractor and a dedicated engine powered generator

 

[GRW]

It'd be interesting to see how the fuel cost per hour running that output compares between the tractor and a dedicated engine powered generator

A nice easy rule of thumb for diesel genset fuel consumption is that every 40kva of load will require 10 Litres of fuel (or 4kva/L if you prefer).
There are of course factors that affect this (e.g. a very big generator on a very small load will use more fuel at that load than a correctly sized machine, that the assumed power factor is 0.8 lagging, plus of course minor differences in engine efficiency).. but power is power and it's a good yardstick.

The other thing people overlook with PTO Gens- is that the tractor and alternator aren't "matched" well on relation to one another - so just as too small a tractor results in a failure to get full power from the pto gen - you can force a too-small pto gen to deliver more than its rating with a powerful tractor. An alternator has windings and cooling to cope with its ratings - force it to do more, and you start turning it into a giant fan-heater as it steadily cooks itself.

 

[Fraserb]

That's a BIG PTO Genny (That is working hard) if it's drawing about 200Hp. Probably over 100kva.
The biggest alternator frame size we can couple to the biggest, highest rated gearbox is about 110kva - so you're right at the top-end.
Once you get up at these power levels, and consider that you need to take perhaps a £200k tractor off the jobs it was bought for to run the genny - I tend to at least suggest to a Farmer that a dedicated Diesel Generator is worth considering, but the final choice is of course the clients

Our genny is only for power cuts, sometimes will go over a year without being used in anger, we try to run it for an afternoon every so often though. Our worry with an engine driven one was engine issues on the day we actually need it, we've a few tractors that can drive it so of one goes down just swap over.

 

[Fraserb]

It'd be interesting to see how the fuel cost per hour running that output compares between the tractor and a dedicated engine powered generator

If I'm honest I've never looked at the fuel consumption when the genny is on, must be over 20lt/hr though going by how often we need to fill the tractor up of its on it a long time.

 

[Robotstar5]

Our genny is only for power cuts, sometimes will go over a year without being used in anger, we try to run it for an afternoon every so often though. Our worry with an engine driven one was engine issues on the day we actually need it, we've a few tractors that can drive it so of one goes down just swap over.

Reminds me of my time in the foundry, we had 2 big standby diesel gensets to power a 30 ton electric holding furnace in case of a power outage, part of the weekly checks on a Saturday morning was to check the gensets and make sure they started automatically. One summer shutdown the local electric supplier wanted to do some work in our substation so we thought just start one of the gensets to keep the lights on and the offices running, do you think we could get it to start when we needed it luckily the other one fired up OK.