operating at less than 540

[botakix]

my brushhog and finish mower, are rated for 540 rpm. i have a kubota 3130 and to maintain this 540 speed on equipment i have to run my tractor at about 2500 rpms. will it hurt anything to run the equipment at lower than 540, so i dont have to wind the tractor up so much?

 

[jinman]

If you keep your blades very sharp, 2000 rpm may be enough. You are lowering the PTO rpm by 20%, so your PTO is turning 436 rpm instead of 540. I don't think 2500 rpm will hurt your tractor, but if you get a good cut at 2000 then I would not worry. I do think your cutter will perform much better at the full 540 rpm as the manufacturer suggests. I know mine sure does.

 

[RWolf]

On my tractor I have a e-pto setting which is about 1600 rpm's. I use that when I'm mowing in lighter grass (pasture).

 

[Squeak n Itch]

If you are truly using the "finishing" mower for just that you can get away with 1,000 RPM. Basically it cuts OK but what you lose here is the better dispersal of clippings which, of course, relies on RPM. Happy Cutting!

 

[Squeak n Itch]

OOPS!! Wrong key, I meant 2,000RPM. 1,000 would be bad for everything.

 

[3RRL]

my brushhog and finish mower, are rated for 540 rpm. i have a kubota 3130 and to maintain this 540 speed on equipment i have to run my tractor at about 2500 rpms. will it hurt anything to run the equipment at lower than 540, so i dont have to wind the tractor up so much?

Personally, I like to run the PTO equipment at it's rated rpm like my brush hog. Or at least close to that to get the best performance and results for what it was designed to do. With that said, if your implement can get the job done with less rpm, than that is perfectly acceptable.
I agree it shouldn't hurt your tractor to run at it's rated 2500rpm like Jim points out, but it makes sense that running it less than wide open can have some benefits. Such as less engine wear over the long run and also fuel savings. I don't know about your 3130, but some tractors have a PTO speed selector. Mine has a 2 speed PTO. In one speed it turns 540rpm at my engine's rpm rating (2300) and in the second speed it turns the PTO at 720rpm. So what I do is use the 2nd PTO speed and run the tractor's engine rpm around 1725rpm. That then spins my PTO at 540rpm in the 2nd range. I do that when I don't need to use a lot of hp to get an heavy duty cutting done.
That does a couple things for me, like I said above. It reduces engine wear over the long run and saves on fuel. It also keeps the engine temperature in the "green zone" when it is super hot out here. Another interesting benefit is that my engine's torque curve happens to produce peak torque at around 1750 rpm, so I am now working at or near the maximum torque and the engine rarely bogs down.
But back to your question, I don't think it would hurt to run your implement at less than 540 PTO rpm if you can get it to perform with satisfactory results.

 

[radman1]

I usually run my mowers slower than rated pto speed. I will run them faster in heavy, tough mowing. Little less wear, little less fuel and a little less mower and tractor noise.

 

[actionaj]

I agree with radman1 I run my MMM or rotary cutter slower than PTO speed most of the time. Less wear and tear and less fuel used and still do a good job.

 

[AndyMA]

On my tractor I have a e-pto setting which is about 1600 rpm's. I use that when I'm mowing in lighter grass (pasture).

Doesn't e-pto still produce 540 PTO rpm, just at lower available PTO hp?

Andy

 

[AndyMA]

I agree it shouldn't hurt your tractor to run at it's rated 2500rpm like Jim points out, but it makes sense that running it less than wide open can have some benefits. .

We go around and around on this. Tractor engines are rated to run at PTO speeds all day long. In fact in manuals like the ones for my Ford 2120 rated PTO speed is called "fast idle".

Of course you can run at less speed if you so desire.

Andy

 

[3RRL]

We go around and around on this. Tractor engines are rated to run at PTO speeds all day long. In fact in manuals like the ones for my Ford 2120 rated PTO speed is called "fast idle".

Of course you can run at less speed if you so desire.

Andy

Hi Andy,
Unless I misunderstood the intent of your reply, I take it you disagree with my statement?
I thought it was pretty comprehensive?
Quote:
Originally Posted by 3RRL
I agree it shouldn't hurt your tractor to run at it's rated 2500rpm like Jim points out, but it makes sense that running it less than wide open can have some benefits. .

 

[GreenWannabe]

Doesn't e-pto still produce 540 PTO rpm, just at lower available PTO hp?

Andy

Not all tractors have an e-pto setting. The smallest ones I've seen with it are utility tractors such as JD5xxx series, which are larger than most compacts.

 

[Lunk]

Not all tractors have an e-pto setting. The smallest ones I've seen with it are utility tractors such as JD5xxx series, which are larger than most compacts.

My Branson 3510i (35hp) has it. It works pretty slick, as long as the green stuff doesn't get too thick/tall.

If there's any actual "brush" to be cut, I'll use the normal setting though. No sense in unecessary lugging of the engine.

 

[machmeter62]

I am/was sorry to see Kubota discontinue the multi-3 speed (540-702-1007 RPM) PTO. Which was STD. in the '78 era. I have a '78 30 hp Kubota with that standard three speed PTO, it gives you the option for MULTIPLE CHOICES for efficency. Nearly "WOT" for mowing seem like a waste in most cases to me? I enjoy the engine noise reduction, and fuel savings too, when the "RPM for POWER" isn't required. But I also like these options for spraying, tilling, BH, and mowing with mine; and the PTO has never had any mechanical problems in nearly 31 yrs. I maybe wrong, but I don't recall if the blue or green ones, had multi-speed PTO's in that era?

 

[kthompson]

Did not notice any mention of ground speed in this. If you are running lower rpm then of course you are getting slower tip speed so you need to make up for that with lower ground speed. It may be you are already running at a slow enough ground speed the slower tip speed is fast enough.

Have a brother in law who likes to run low rpms when he is cutting weeds in his field. He runs a normal ground speed and can not understand why the cutting looks so rough. kt

 

[RWolf]

Andy, unfortuantely not on my tractor. As far as I can tell it's just runs the PTO at about half speed. At least I haven't seen anything in the owners manual about it. Sounds like a good question for my dealer.

 

[fixin40]

My tractor states that for 540RPM about 2500RPM is necessary but I have had good luck so far with 2100RPM. Sharp blades make a big difference I think and the slower speed will save you some fuel. Diesel engines have pretty flat torque curve so the lower RPM should not change your power output that much.
My 2 cents

 

[tony123]

I've been wondering about this myself. When I'm mowing, there is a large area that I have to go up and down a short hill. No sooner does the bushhog get up to speed than I am stopping it to reverse direction. This happens nearly 50 times when I do that particular hillside. Regardless of engine rpm, it just doesn't have enough time to get the bush hog up to the 540.

If I run at 2500rpm, it puts a pretty good jolt through the pto each time. Therefore, I try to be easy on the equipment and run at more like 1500rpm. In addition, when on a hillside, I try to be smoother, and lower engine speed helps with this.

I thought about running in the faster pto gear (as Rob suggested). I will try that.

Any suggestions?

 

[Gary Fowler]

Tony 123: sounds like you need to invest $40 in an overspeed clutch to allow the bushhog to keep spinning when you stop to change gears. Then you will only loose a small amount of RPM between gear changes.
My Yanmar has multi-speed selection PTO also like someone said their Kubota has. I run mine in 720 RPM gear but at reduced throttle by 25%. This saves fuel, provides good tip speed on the blades and still leave me plenty of power for most applications. I run in a gear range that allows me to go fast up to 8 mph in 3rd but I can powershift down to 1st for heavy stuff to slow me to about 4 mph. Cant beat that powershift transmission.

 

[redneckford]

Tony 123: sounds like you need to invest $40 in an overspeed clutch to allow the bushhog to keep spinning when you stop to change gears. Then you will only loose a small amount of RPM between gear changes.
My Yanmar has multi-speed selection PTO also like someone said their Kubota has. I run mine in 720 RPM gear but at reduced throttle by 25%. This saves fuel, provides good tip speed on the blades and still leave me plenty of power for most applications. I run in a gear range that allows me to go fast up to 8 mph in 3rd but I can powershift down to 1st for heavy stuff to slow me to about 4 mph. Cant beat that powershift transmission.

Word of caution!!!----Be sure to not throttle up to full 720rpm or 1000rpm cause many 540rpm designed gearboxes can not take the extra speed---tends to kill the bearings quickly!!!!!