Is it time for a gasoline engine tractor?

[Soundguy]

If its at the point it will lug, IE, more throttle won't speed her up, but she's not loosing rpm... At that magic point, I think you could call that 100%. IE, adding any more load starts the stall and loss of rpm.

Reason I say that is 100 and not 90, is because at 90, you still have more hp available.. 10% to be exact. Remember hp is a calc of 'work done'. If you have hp left over (10%) you have not yet reached maximum work capability.

At 100% hp you are doing the max work you can.. As long as that max hp/work is no less than needed for the load applied, you aren't stalled.. You are working at max capability.

 

[buickanddeere]

Would you?

If you have 10% more hp available.. And your load only needed 3% more.. You wouldn't be lugging!

I am going have to agree with SoundGuy

 

[Turbys_1700]

The owner's manual for my Workmaster does not make any mention of load or duty cycle. The only reference to proper break in procedure for the engine is to not load the engine during the break in period. They define loading as running the engine where when you add throttle the tractor can't increase speed of operation. I've run the tractor thus far mostly at the rated RPM to run the PTO in bush hogging and finish mowing. I had always heard to vary throttle input on new engines and I have done that as much as possible but the owner's manual makes no mention of it. I need to read it some more. First time I've had to break in a new engine.

 

[RaydaKub]

If its at the point it will lug, IE, more throttle won't speed her up, but she's not loosing rpm... At that magic point, I think you could call that 100%. IE, adding any more load starts the stall and loss of rpm.

Reason I say that is 100 and not 90, is because at 90, you still have more hp available.. 10% to be exact. Remember hp is a calc of 'work done'. If you have hp left over (10%) you have not yet reached maximum work capability.

At 100% hp you are doing the max work you can.. As long as that max hp/work is no less than needed for the load applied, you aren't stalled.. You are working at max capability.

I follow your logic, but I just want to use a real life example to make sure I'm on the same page. When I was in college, my dad replaced me with a bigger tractor. The Case 930 would pull a bigger plow than the 730. So I was using it to plow some alfalfa ground. In the low ground, it would lug down about 500 rpm, but keep fighting through it and recover the rpm after about 200 yards. I never had to downshift, but the black smoke was rolling out. So at what point was I at 90% and 100% ?

Dang, I miss that beast. According to Tractordata, it was 80 pto hp, but pulling that 5/16's it kept up with the neighbor's Deutz that I think was the DX110 at 102 hp.

 

[buickanddeere]

I follow your logic, but I just want to use a real life example to make sure I'm on the same page. When I was in college, my dad replaced me with a bigger tractor. The Case 930 would pull a bigger plow than the 730. So I was using it to plow some alfalfa ground. In the low ground, it would lug down about 500 rpm, but keep fighting through it and recover the rpm after about 200 yards. I never had to downshift, but the black smoke was rolling out. So at what point was I at 90% and 100% ?

Dang, I miss that beast. According to Tractordata, it was 80 pto hp, but pulling that 5/16's it kept up with the neighbor's Deutz that I think was the DX110 at 102 hp.

Many people mistake torque rise for power.

 

[SteveM70]

Many people mistake torque rise for power.

When it comes to tractors, torque rise is power.

 

[buickanddeere]

When it comes to tractors, torque rise is power.

What you are thinking of is not described with the term "power".

 

[Redneck in training]

PTO power is no maximum or rated power. Just look at the power, torque and fuel consumption curves. In example Kubota 1505 produces maximum power 33HP at 3300 rpm but my tractor has PTO power 28 HP set at 2500 rpm. Investigating the chart closer you would see that 2500 rpm is very close to maximum torque and the best specific fuel consumption. Simple mathematics will show that the engine produces 85% of rated power at PTO speed. Now if you are engaging in heavy ground work and going gets tough you might up the speed to 3300 rpm and use full power. Based on my brief experience the the engine will run noticeably hotter.
From above it is apparent, while running a generator, you will be using 85% of power at maximum load. So my guess is you could run it at that load continuously.

 

[Turbys_1700]

I think that the Nebraska tests run tractors at rated PTO RPM's and identify the HP level at different time intervals. For a test to be considered accurate they run them for 2 hours? I know that in the 60's my dad said that when new a Allis-Chalmers would come into the dealership they would hook them up to the dyno and typically a 50 HP rated D-17 would initially pull 55 plus HP. After 15 minutes or so that rated output would be reduced somewhat to usually around 53 or so. Back then Allis-Chalmers and other manufacturers rated tractors at the PTO. They were always underrated from he factory. If you look at the Nebraska test for those tractors the tests will show higher output than stated HP.

 

[Industrial Toys]

Our JD also had showed more on the Dyno then rated. It should for the fuel that it uses!

As for generators. That's why it important to start with something that runs at 1800 rpm. It's just purring along putting out only about half of what the engine is capable of. When my little JD 770 (Yanmar) ran my Onan 15 kw PTO genset, you pulled that throttle wide open to get 540/60 cycles. As the song says, "that's all there is and there ain't no more"!

As I mentioned several times before, I tried an experiment with a 2-1 PTO gearbox, thinking I could use this for light loads. The tractor would not even turn it with no load! It just surged in a most disturbing way, trying to catch it's breath. That genset did have a speed-up sprocket driven arrangement, that did not help. The Rotor spun quite quickly.