Proper PTO RPM?? Will too low hurt the tractor?

[sweep]

I have a 2006 TC45A and it say's to run the pto at 540 rpm. Also in my Brush Hog owners manual it says to set the rpm at 540.


I rarely ever run my pto speed at 540, more like 300-350 and the 7' brush hog seems to cut the field just fine. Occasionaly I will throttle up to a higher speed in higher grass.

540 seems like a fuel waster and extra wear on the tractor when not needed.

Will the lower speed hurt the PTO? I'm thinking no, but just wanted to make sure. I know some tranmissions are designed for a certain operating range and low range will hurt them just as over revving range will.

Thoughts?

Thanks

 

[JC-jetro]

Sweep,

Tractor and implement are designed to be operated at rated engine rpm or the rpm needed to operate the PTO driven rotary implement @ 540 for hours on end. Saying all of that and you only need to spin the pto only as fast as you need to get the job done. My soil where I have my garden is pretty good,and I have never exceeded 1500 rpm engine rpm at whatever pto rpm that happens to be get a perfect mix. In the areas that I might have thick weeds of all kind of young sapling of unwanted tress and such I have run my tractor close to 2000 rpm. You gain nothing extra by running the pto rpm at 540 if you can achieve desired result at lower rpm. My impression is that you'll end up adding more life to your tractor and implements when they are stressed out less than design point.

JC,

 

[jinman]

I'd say to stay above 2000 engine rpm and you have no worry. The 2000 rpm will keep the engine from bogging down and be well up on the torque curve. Maintaining a minimum rpm will also keep your cutter blade cutting with the least input torque. When you have that cutter spinning at 540 rpm, the inertia helps to cut the grass. At 350 rpm, the engine will feel the added torque as you cut through deeper grass/brush. So, if you are getting a good cut and your tractor's engine is not bogging down at all in the higher grass, then you are probably hurting nothing. If the engine does bog down, kick up the rpm so that you get some help from inertia. Everything comes together at 540 rpm.

Aren't you glad that 540 rpm is the standard? Just think what a zoo it would be if everyone had optimal rpm for their cutters from 350 to 600 rpm.

 

[OhioGuy]

My dad and I used to have this discussion all the time regarding garden tractors.
The Cubs all suggest running at full throttle, which I do, my dad ran his at maybe 3/4.

We both got the result we wanted and I probably did burn more fuel, although my ground speed was much higher.

I think it's another personal preference thing!

Curt

 

[dqdave1]

Cubs ( air cooled engines) are designed to get the best air circulation at WOT. It has nothing to do with the attachments.

 

[Soundguy]

Ok.. so lets see.. your tractor manual, and implement manual are telling you what to run the pto at.. IE.. the rated speed.

I'm assuming you are a mechanical engineer and a mechainic since you are 2nd guessing the directions of the equipment manufacturer and the tractor manufacturer.

Too low of speed and you are out of your power band and the engine can bog down.. that ain't good.

540 to much wear? You machine is rated to run that speed.. thus you are at acceptable levels of wear at that speed... sure.. you are getting by with slightly less wear at lower rpms.. from a scientific stand point... you'd need a star trek tri-corder to measure the difference in wear though...

maintain your machine correctly.. and don't be afraid to use the tool at it's rated level of performance.

Kinda like buying a shovel, but never taking 'full scoops' in order to not wear it out.

remember.. you can always park it (and never use it again) in a sealed room, on jackstands and it will last a whole lot longer! see where possible and practical cross and part ways ?

soundguy

I have a 2006 TC45A and it say's to run the pto at 540 rpm. Also in my Brush Hog owners manual it says to set the rpm at 540.


I rarely ever run my pto speed at 540, more like 300-350 and the 7' brush hog seems to cut the field just fine. Occasionaly I will throttle up to a higher speed in higher grass.

540 seems like a fuel waster and extra wear on the tractor when not needed.

Will the lower speed hurt the PTO? I'm thinking no, but just wanted to make sure. I know some tranmissions are designed for a certain operating range and low range will hurt them just as over revving range will.

Thoughts?

Thanks

 

[allenr]

I never use rated rpm if the job can be accomplished, without bogging down, at lower revs.

Seems like a waste of fuel to me too.

I have a couple tractors with 540,740 and 1000 pto's, they're a good idea too.

 

[Hooked_on_HP]

I am not a mechanical engineer but I am a mechanic and I don't always run at 540. My tractor is a gear tractor and when mowing, 7th gear is slower than I want to mow and 8th is to fast at 2400rpm/540PTO So I drop the rpm's to around 2100 and mow in 8th. It gives me a good cut and doesn't beat me to death. If it starts to bog down I drop a gear and increase the RPM's.
Bill

 

[Philscbx]

If it starts to bog down I drop a gear and increase the RPM's. Bill

That's more than fine. I do the same thing with skid steers.
99.7 will run it WOT when there is no rotary attachment on the machine that would need the flow.

It operates, skiddish, and touchy on the controls at WOT to make fine precision moves. 1600 rpm is plenty for most work. 1/3 less noise and fuel.
I can back drag snow just above idle if I'm right next to a row of cars.
So far after many years of doing this, not one car or skyscraper glass has been bitxh-slapped with the bucket.

 

[browns40]

Hey sweep,

Another long standing discussion here... like Soundguy said, these machines are designed to run at those speeds all their lives... also it sets a standard speed for multiples brands and attachments to run at and be rated towards...

Will you hurt your tractor running a fertilizer spreader at 1100 rpm's? No Way.
Other attachments you want to be high up in your torque band to avoid lugging the engine, and also have extra momentum working in your favor for smacking a rock out of the way before your tines or blade, and driveline fetch up against it.

If you know your area, what you're going to run into, and get the effect you want, then running at a lower speed suitable to the job is a fine decision. I do this at home with everything, and at all different speeds.

When I am in unfamiliar ground, I get the speed up to have that extra power getting things done and hopefully bouncing off or through what I didn't know I was about to hit... Slip clutchs are nice too!