Is there a way to overdrive PTO speed?

[NebraskaKen]

I've recently bought a PTO driven generator to provide power when our lines go down.

The generator must be driven within a very narrow margin (green zone) in order to provide safe power to the house.

I have a 540 rpm PTO drive on my JD 4710 compact and to get into the "green zone" I need to run it at about 2300 rpm, which I hate to do since the tractor is spinning the generator with little effort.

Without digging into the gear box, which drives the generator, is there any other way, or attachment, I can use to overdrive my PTO so that I can use less RPM running the generator?

 

[kennyd]

Welcome to TBN

The short answer to your question is NO, there is no practical way to do that.

BUT, Your machine will run forever at 2300 rpm without blinking, no damage will be done. This is just one reason why some here do not like PTO gennies if you search some of the threads on this very issue!

 

[bjcsc]

The only option you have would be to use a speed increaser on your PTO. Depending on the kW of your gennie, that may not be practical, i.e. you may need your rated RPM HP to spin it (which you won't have at lower RPMs).

Like kennyd said, the noise is the only problem. Your tractor will be happy to run at 2300 all day long...

 

[Rara Avis]

I've recently bought a PTO driven generator to provide power when our lines go down.

The generator must be driven within a very narrow margin (green zone) in order to provide safe power to the house.

I have a 540 rpm PTO drive on my JD 4710 compact and to get into the "green zone" I need to run it at about 2300 rpm, which I hate to do since the tractor is spinning the generator with little effort.

Without digging into the gear box, which drives the generator, is there any other way, or attachment, I can use to overdrive my PTO so that I can use less RPM running the generator?

http://www.omafra.gov.on.ca/english/engineer/facts/00-059.htm

 

[Soundguy]

I've recently bought a PTO driven generator to provide power when our lines go down.

The generator must be driven within a very narrow margin (green zone) in order to provide safe power to the house.

I have a 540 rpm PTO drive on my JD 4710 compact and to get into the "green zone" I need to run it at about 2300 rpm, which I hate to do since the tractor is spinning the generator with little effort.

Without digging into the gear box, which drives the generator, is there any other way, or attachment, I can use to overdrive my PTO so that I can use less RPM running the generator?

Your tractor likely is ( should be ) rated to run at it's full pto speed and HP till it's fuel tank caves.

As the others said.. you'd ahve to have a seperate gearbox or other contraption to multiply your pto speed in order to run lower rpms.. this will reduce the hp at the pto.. and may take your machine out of it's 'sweet' torque curve as well..

Is your pto gen going to consume at least half your rated pto or thereabouts... IE.. I'd have no qualms about running a 10kw gen on a 40-50 hp machine. What that gets you is when a 8kw load snaps on.. the machine doesn't stumble and falter.. it keeps right on trucking.

I've used a 95 and 70 hp machine to run a 12.5 kw pto gen.. for sure overkill.. but as I said.. near max loads don't touch the rpm or frequency like if i was running it on a 30hp machine.. etc.

soundguy

 

[rbargeron]

I've recently bought a PTO driven generator to provide power when our lines go down.

The generator must be driven within a very narrow margin (green zone) in order to provide safe power to the house.

I have a 540 rpm PTO drive on my JD 4710 compact and to get into the "green zone" I need to run it at about 2300 rpm, which I hate to do since the tractor is spinning the generator with little effort.

Without digging into the gear box, which drives the generator, is there any other way, or attachment, I can use to overdrive my PTO so that I can use less RPM running the generator?

There's an interesting web article here about an Italian-made parallel shaft increaser/reducer that uses a planetary style gear setup. I've never seen it for sale in the US but maybe it's available somewhere.

 

[Iplayfarmer]

Everyone else's input is pretty much spot on about not being any problem for your tractor to run at PTO speed forever, but for academic reasons, the answer to your question is yes, there is another way to overdrive your PTO. I'd actually guess that there are a bunch of ways. The simplest would be to get a set of pulleys and mount them on a platform so that you're driving a very large pulley directly off the PTO shaft which in turn drives a very small pulley attached to the generator.

If you're really creative, get a manual transmission out of a small car and put it inline somewhere. If you did it right you could probably even change gears to adjust to your load.

There was another guy on here wondering what to do with the gearbox off of his bush hog. I think we figured that the gear ratio was about 2:1. You could mount the genny sideways on a platform and couple it to the bush hog gear box with an adapter from Surplus Center. Then you could run your tractor at 1150 RPM and still have useable power from the genny.

If you're in it for the big wow factor you could drive a PTO hydraulic pump and run the genny with a hydraulic motor. In fact, your current hydraulic pump might have enough flow already to run the generator. By picking a motor with the right displacement, you could pre-determine how fast your tractor would have to run to hit the right RPM number.

 

[schmism]

Everyone else's input is pretty much spot on about not being any problem for your tractor to run at PTO speed forever, but for academic reasons, the answer to your question is yes, there is another way to overdrive your PTO. I'd actually guess that there are a bunch of ways. The simplest would be to get a set of pulleys and mount them on a platform so that you're driving a very large pulley directly off the PTO shaft which in turn drives a very small pulley attached to the generator.

If you're really creative, get a manual transmission out of a small car and put it inline somewhere. If you did it right you could probably even change gears to adjust to your load.

There was another guy on here wondering what to do with the gearbox off of his bush hog. I think we figured that the gear ratio was about 2:1. You could mount the genny sideways on a platform and couple it to the bush hog gear box with an adapter from Surplus Center. Then you could run your tractor at 1150 RPM and still have useable power from the genny.

If you're in it for the big wow factor you could drive a PTO hydraulic pump and run the genny with a hydraulic motor. In fact, your current hydraulic pump might have enough flow already to run the generator. By picking a motor with the right displacement, you could pre-determine how fast your tractor would have to run to hit the right RPM number.

I think at the end of the day efficiency should be a goal. while the tractor may be happy running at 2300 rpm all day and night, your burning (for example) 23 hp of fuel even if your max load is only 15hp worth of draw.

a pulley setup would work best. and is relitivly easy to impliment with off the shelf parts.

while hydraulic version is possible , you wind up with a lot of loss in converting the mechanical rotational motion into fluid flow and then from fluid flow back to mechanical rotational motion. so that would be the lest efficient.

 

[denmansoft]

In general I agree, Run it as these engines are designed for it.
Don't try that with a Car engine..... They rate them for marketing purposes what you can get in a short term peak.
Another option is to get a tractor like mine with a 2 speed PTO. If I were just running relativley lite loads I can put my PTO on 1000 RPM setting and drop my engine RPM from 2600 to about 1300 and have 540 on the PTO.
Needless to say ther is lots one could do wrong with this setup.....

I have an 8500 watt Gas genset so I haven't tried this yet.

I will be using my chipper in this mode next time out.

 

[Soundguy]

I think at the end of the day efficiency should be a goal. while the tractor may be happy running at 2300 rpm all day and night, your burning (for example) 23 hp of fuel even if your max load is only 15hp worth of draw.
.

I disagree... fuel usage will be based on load.. not max hp the tractor makes

IE.. My 95 hp tractor and my 70 hp tractor both pulling the same 10' mower to mow the same pasture.. By your logic, the larger tractor will use lots more diesel ( 25hp more! ) to do the same job.

Wonderfull reality is that both use right at 5g of diesel.. telling me the job is being done with much less than 70hp.. etc..

soundguy