M8540/M9540 540/1000 rpm PTO Conversion install

[ovrszd]

Some manufacturers make PTO systems now that run at a reduced engine speed. The method used varies, but the end result is the same. Wish I had something like that on my tractor.

Most of my PTO use is running a 10' 1000rpm brush cutter. I wish I could do that at a reduced engine speed. I have plenty of HP for the job and could benefit from less engine speed

The conversion kit I installed was to specifically change the tractor's PTO speed from 540 to 1000. I guess I could convert the PTO shaft on a 540 attachment to the 21 spline of my 1000 rpm shaft and then run the engine at a reduced speed to attain 540rpms to the attachment.... Wonder if anyone has ever tried that???

 

[xring100]

I believe I have seen adapters at tsc
Yep here it is
21-Spline To 6-Spline Adapter - Tractor Supply Co.
https://www.google.com/url?sa=t&sou...rE0jWfKpd1CDHJEDg&sig2=4eJWt_EjW4h30VNxzhZYYA

 

[bjmsam]

The conversion kit I installed was to specifically change the tractor's PTO speed from 540 to 1000. I guess I could convert the PTO shaft on a 540 attachment to the 21 spline of my 1000 rpm shaft and then run the engine at a reduced speed to attain 540rpms to the attachment.... Wonder if anyone has ever tried that???

That's exactly what I wanted to do, but further research revealed that it may not be such a good idea for my application anyway; a factsheet published by the Ontario Ministry of Agriculture and Food titled Tractor-Driven Generators: Producing Quality Power states, "Operating a tractor with a 1000 rpm PTO at approximately one-half its rated engine rpm to deliver 540 rpm to the generator is not a recommended practice - do not operate your tractor with 1000 rpm PTO and half engine speed." Oh, well.

 

[ovrszd]

Dave,,, forgot about those, that would be easier than converting the spline end of the PTO shaft and is easily reverseable. I guess the only issue would be PTO shaft length, with the adapter the shaft might be too long?? Thanks for posting this!!!

 

[ovrszd]

That's exactly what I wanted to do, but further research revealed that it may not be such a good idea for my application anyway; a factsheet published by the Ontario Ministry of Agriculture and Food titled Tractor-Driven Generators: Producing Quality Power states, "Operating a tractor with a 1000 rpm PTO at approximately one-half its rated engine rpm to deliver 540 rpm to the generator is not a recommended practice - do not operate your tractor with 1000 rpm PTO and half engine speed." Oh, well.

Hmmmm,,, wish they had elaborated on the problem with doing that. I can't think of any mechanical reason that it wouldn't work??? My tractor's electronic dash gives me PTO shaft speed. It can be switched back and forth between 540 and 1000 depending on which you are using at the time. By leaving my dash setting on 1000 and setting the tractor's engine speed to attain 540 I'd be accurately controlling the attachment speed so I can't see how I could damage it. By running the 1000rpm PTO setup at a reduced speed I can't see that any damage to the tractor would occur. Curious why they say that???

 

[bjmsam]

Perhaps it would not be a problem for your application.

Operating at Half Engine Speed

Farm tractor diesel engines are designed to develop optimum horsepower and torque at a specific rated engine speed.

Operating a tractor with a 1000 rpm PTO at approximately one-half its rated engine rpm to deliver 540 rpm to the generator is not a recommended practice.

Chart 8 shows the results of one test where this mode of operation was attempted. The frequency decreased by 10% when 30 % of rated load was applied and by 16% at 60 % of rated load. Clearly unacceptable, for producing quality power.

Chart 8. Significant change in frequency takes place when operating at half of rated engine rpm.

While the engine horsepower would be significantly reduced at half the rated engine rpm, the bigger problem is that at this speed the engine is operating on the unstable side of the torque curve. An increase in load will cause a reduction in engine speed, which causes a reduction in torque, which causes a reduction in speed, resulting in tractor stalling or speed cycling erratically up and down.

Some tractors are now equipped with an "economy" 540 rpm PTO as well as the "standard" setting. One tractor with this feature was tested. Operating with the "standard" setting produced a 2% drop in frequency from no-load to full-load operation. The frequency drop while operating in the "economy" setting was in excess of 6% for the same loads.

When selecting the engine operating speed to deliver 540 rpm at the PTO:

• set the engine close to manufactures recommended engine speed for 540 rpm
• adjust frequency to 60-62 Hz
• use a factory "economy" setting for light consistent loads
• do not operate your tractor with 1000 rpm PTO and half engine speed.

 

[xring100]

Dave,,, forgot about those, that would be easier than converting the spline end of the PTO shaft and is easily reverseable. I guess the only issue would be PTO shaft length, with the adapter the shaft might be too long?? Thanks for posting this!!!

No problem

 

[ovrszd]

I agree that if I'm operating an attachment that requires maybe 80% or higher of my tractor's HP/Torque that reducing engine rpms would not be effective and would make it difficult to maintain constant attachment speed.

I didn't see anything in the data that indicated damage to the tractor or attachment. It just warned of the inability to maintain speed. I agree with that.

I think for light duty attachments it would not create a problem. I've got a 6' 540rpm brush cutter. I'll hook it up next Summer and try running my tractor at reduced engine speed using the 1000rpm shaft converted. Not really a great test because the cutter is way below the tractor's ability to operate, but I'll give it a try. Wish I had a 540 attachment that would load the tractor to test with. I'm curious if a noticeable savings in fuel consumption can be noticed.

 

[rbargeron]

Back in 2002, I posted the prior thread about converting to 2-speed pto . Later in 2008 I converted another L5450 the same way. Except for the L4350, L4850 and L5450, I've not seen any other models where the conversion is this direct and low-cost (about $300 in parts). For my uses, 150% is a more versatile second speed.

For the big engines in the M8540 and M9540 the replacement gearbox from Kubota fills a need - its good that they offer it.

Regarding other tractor brands and models, the design requirements for a pto speed increaser drive the cost high. It should be (1) shaft mounted and supported (2) rotate the same way (3) provide step-up of about 50% (4) input and output on the same centerline (5) include a bi-directional torque resistance (6) sealed oil-bath housing (7) compact and light-weight. For a time there was one like this (Comer A-20A from Italy) but it was priced around $1k when I inquired.

The big factor in all this is that the engine has to be big enough to have plenty of power and good governor response when running at lower rpm with smaller loads. My L5450 makes around 50 pto hp so the higher pto ratio (780 rpm) works fine for things like snowblower, rotary and finish cutters, and a pto generator. I run the engine at 1700, where it makes maybe 25% less hp, but still responds well to varying load.

 

[ovrszd]

I probably wouldn't have bought my conversion just as an add-on. I was shopping for a brush cutter and found a JD M1008 1000rpm for $1800. All others I had found were in the $3K range. I decided I could add the PTO conversion and buy the cutter for what I'd pay for any other cutter I'd found. Looked like a win/win to me.

I looked at a parts breakdown of my tractor to figure out what I was getting for the money. I really thought I'd get a box of parts and have to put it all together, similar to the conversions you are talking about. I was pleasantly surprised when it came assembled. I took my time installing because I just didn't see how it could be that easy. Now that I've done one I could do another in 30 minutes. Takes longer to deal with the fluid than anything else. Also came with a longer drawbar because it moves the shaft rearward a few inches.

Thanks for your posts.