Full RPM or high idle? Bush hogging fuel efficiency

[TripleR]

Wrong again.
I think the redneck in training, and sounguy log-on posters are the same guy. posting the same made up science. Am I right?

No you're not; different people.

 

[PoorPlowboy]

Not to add another curve to this thread, but what about those of us who have 2 speed PTO's (my Kioti is 540/1000). Does using the 1000 rpm setting at a lower engine speed help or hurt wear/fuel economy?

Likewise, does it damage an implement to run it at a higher PTO speed? Dealer told me it shouldn't, and so far he seems to have been right, but I'm concerned about long-term.

Running the 1000rpm pto at a 540 final speed is going to severely lug the engine way too low in the torque curve. You'll likely choke the engine out every time you find thicker grass. Balancing and harmonics will wreak havoc on your implements if they are intended for 540. 1000rpm implements are balanced at 1000rpm.

 

[jejeosborne]

Running the 1000rpm pto at a 540 final speed is going to severely lug the engine way too low in the torque curve. You'll likely choke the engine out every time you find thicker grass. Balancing and harmonics will wreak havoc on your implements if they are intended for 540. 1000rpm implements are balanced at 1000rpm.

Why is balance and harmonics an issue? The implement will still only see 540 rpms on the input shaft. It doesn't care what internal gear the tractor is using.

 

[PoorPlowboy]

Why is balance and harmonics an issue? The implement will still only see 540 rpms on the input shaft. It doesn't care what internal gear the tractor is using.

Does this not answer your question?

Likewise, does it damage an implement to run it at a higher PTO speed? Dealer told me it shouldn't, and so far he seems to have been right, but I'm concerned about long-term.

 

[DarkBlack]

Running the 1000rpm pto at a 540 final speed is going to severely lug the engine way too low in the torque curve. You'll likely choke the engine out every time you find thicker grass. Balancing and harmonics will wreak havoc on your implements if they are intended for 540. 1000rpm implements are balanced at 1000rpm.

Running a 1k pto at 540 would reduce the required torque. I think you just typed that backwards, as I see your point. All ICE's have a rising torque curve to peak tourqe, then drop. I agree nominal best efficiency is somwhat around peak tourqe, which is always below peak HP, which is what tractor sales push. If you run at peak HP rpm you have a climbing torque as you drop rpm's due to load, so your engine 'seems' to have great extra power, but you burn fuel. If you run at peak torque( lower rpm) , you have great fuel efficiency, but when you load to above the torque value you drop rpm, and then your engine is in the decending range of the torque curve, and you stall your engine

 

[jejeosborne]

Does this not answer your question?

Yes it did. Thanks. I wouldn't operate above 540 either rpms at the input shaft with either gear.

 

[foreman Etexas]

My thoughts if your working it without lugging it and say 100 or at 540 you should get the best performance from tractor(theres that sound of the motor when your at the sweet spot,not to much,not to little). My thoughts are also if its that short,and dont have to run close to 540,not going to mow it anyways not tall enough yet,cause thats is poor fuel efficiency. Dont get me wrong not saying I let my place get over grown but it doesnt stay like a park either(not that,that is a bad thing,park like is PRETTY),and when my wife aint looking I turn the cows in for alittle fertilizing,the calves actually weedeat pretty good around the house,I may add. But oh if the wife finds a cow pie while walking in the yard,it is also amusing some of the words she may use,while washing her shoes off,I just say honey thats why they made boots.

Everyone have a safe and great LaborDay weekend

 

[jejeosborne]

My thoughts if your working it without lugging it and say 100 or at 540 you should get the best performance from tractor(theres that sound of the motor when your at the sweet spot,not to much,not to little). My thoughts are also if its that short,and dont have to run close to 540,not going to mow it anyways not tall enough yet,cause thats is poor fuel efficiency. Dont get me wrong not saying I let my place get over grown but it doesnt stay like a park either(not that,that is a bad thing,park like is PRETTY),and when my wife aint looking I turn the cows in for alittle fertilizing,the calves actually weedeat pretty good around the house,I may add. But oh if the wife finds a cow pie while walking in the yard,it is also amusing some of the words she may use,while washing her shoes off,I just say honey thats why they made boots.

Everyone have a safe a great LaborDay weekend

Would you rather hit the cow pie at full throttle or just above idle? LOL.

I have hit a dog pie with the finish mover discharging upwind and that wasn't pleasant. You have a good weekend too.

 

[tcreeley]

I use a NH TC30 (30 hp) to pull my 60" tow bush hog. I go at 1800 -1900 rpm. It does a good job knocking grass and saplings down. The engine sounds good- no strain, no lugging. For me it is like driving a manual - you shift when you know it is time to. I could run it faster- but it does not need to- wasted power. I have a 9x3 transmission and have it in M/2nd. M/3 would do fine with a 2000 rpm- but I get tired of bouncing around on the seat.--- I think 2400 matches my 540- no need for that-overkill on this tractor pulling this 5' bushhog.

 

[Redneck in training]

Wrong again.
I think the redneck in training, and sounguy log-on posters are the same guy. posting the same made up science. Am I right? It's not just the bs made up science you pulled from your lower cavity on the previous pages, but "you" both try to morph the issue when you post total bs science and your statements from previous posts contradict what you post later to try to save face.
Oh, and again, what you posted above is wrong as usual.

You resorted to insults instead explaining why I am wrong. There are other people beside me reading the post. They would like to know why you are right. If what you are saying is n fact true then we would have tractors and implements designed to run at low rpm to save fuel. But that is not the case isn't it. The reason that we have tractors that run at higher rpm is that they have the best efficiency there. To perform certain task (such as grass moving) require certain power regardless of rpm selected. That power is generated by burning fuel at certain rate. At the best efficiency the highest amount of fuel is converted to work. Once you are above or below the best efficiency band you use more fuel/generated power.
I will give you a better example:
Let say you are using a generator to generate 10kW of power required by a load (in example welder). The generator will use the same power from the driver (engine) regardless of rpm but might use less fuel at the best efficiency rpm.

Grass mowing is more complicated. For sake of discussion we (I) assumed that the quantity of grass mowed and the quality of the task are equal. I guess you can safe fuel at the cost of quality. My experience is that when mowing thick grass the mower has tendency to overload the engine if going to fast. This tendency will only increase at lower rpm. So at the end the same task will take longer time while using about the same amount of fuel per unit of time. That why I am saying you might not save much (if any) fuel to complete the task. If you are just clipping grass may be. But I doubt that too. You are assuming that at lower rpm the mower will use less power but I think that is not the case.