ROTARY CUTTER SPEED

[flINTLOCK]

Most posts I've seen refer to running RC about 540 rpm. A farmer bushogs the brushy areas around my development and his tractor is so quiet while running, I know he's running at less than 540. Any harm in that??

 

[RoyJackson]

Most posts I've seen refer to running RC about 540 rpm. A farmer bushogs the brushy areas around my development and his tractor is so quiet while running, I know he's running at less than 540. Any harm in that??

You won't get a clean cut..that's about it. Maybe a bit more vibration.

As far as the farmer...you ought to ask him. I'm guessing he may be running his tractor at a lower RPM, but the PTO is still doing 540 RPM.

My cutter is pretty quiet once it's spun up to operating speed and if I'm not going through any heavy stuff...but I know "quiet" is a relative term.

 

[Z-Michigan]

My tractor is quieter at 2200 rpm (which equates to 540 PTO) than it is at 1400-1800 rpm which I use for non-PTO tasks. And the cutter doesn't make much noise unless it's chewing on something. I would not be surprised if the farmer is operating at 540 PTO RPM (or 1000rpm if he has a big setup made to work at that speed). Many JD models include an "economy" PTO that allows 540 PTO rpm at a lower engine rpm for lighter tasks, while allowing the same 540 PTO rpm at higher engine rpm for max hp.

I agree that there shouldn't be an issue with running below recommended rpm, but the cut quality will suffer pretty badly.

 

[flINTLOCK]

Thanks. I'll ask him next time through.

 

[riptides]

Most posts I've seen refer to running RC about 540 rpm. A farmer bushogs the brushy areas around my development and his tractor is so quiet while running, I know he's running at less than 540. Any harm in that??

Depends on the cutter and the cuttie. With various type of grasses I vary the RPM speeds dramatically on the go. I have a mixture of weed, fescue, orchard grasses and what not. Some of the weeds go up to four feet, they may get the 540rpm. Some of the grass areas may get conciderably less rpms.

You'll have to operate and figure out what is best for you. I rarely operate at full rated rpms 100 percent of the time.

Blade, terrain and material type all factor in to the rpms needed for a "good" cut.

-Mike Z.

 

[Soundguy]

At proper pto /eng speed.. i can't hear my batwing mower unless it is really eating woody stuff.

Soundguy

 

[flusher]

Most posts I've seen refer to running RC about 540 rpm. A farmer bushogs the brushy areas around my development and his tractor is so quiet while running, I know he's running at less than 540. Any harm in that??

My neighbor has a Ford 8N that generates 545 rpm at the pto at 1500 rpm engine (gas). My 2005 Kubota B7510HST generates 540 rpm pto at 2600 rpm engine (diesel) for my KK brush hog. The 8N purrs along when he brush hogs. My Bota screams.

 

[JerryG]

This question has come up many time over the years. I have never seen a cutter damaged by running a slower RPM, but thought it would be interesting to see what a manufacture would say. So, I emailed Woods about this and here is what they said.

No damage will be done to your 5' rotary cutter if operated at slower than 540 RPM. The cut quality may not look as nice, because the blades are rotating slower. Operating at a slower RPM will require more HP from your tractor.
Let us know how we can be of assistance.
Xxxxx Xxxxx
Special Accounts Coordinator
Woods Equipment Co.

 

[Farmwithjunk]

It's obvious that some folks feel very passionate about this subject. It's equally apparent that the results are varied from person to person, mower to mower and tractor to tractor.... and let's not forget grass and weeds to grass and weeds.

I just walked in from 3 hours of mowing. I cut for about an hour with my Massey 150 and the 6' Bush Hog 286. 540 rpm on the pto is @ 1750 engine rpm. I cut a while at that speed. I cut for a while at 1500 rpm. I cut a while @ 1400 rpm. And I'd bet NO ONE, maybe not even I could walk out in the field and tell where the slower or faster engine speed was used. Then I fired up the Deere 6430 and 15' batwing. I varied rpms as much as 800 revs from slow to fast. Same deal. You can't tell the difference..... EXCEPT..... on the fuel gauge. The Massey will run all day on aprox. 2-1/2 gallons less fuel by holding at 1500 rpm as opposed to 1750. Not sure on the Deere, as I've never really checked the "milage". The Massey has been with me for 36 years. If using it "easy" was going to hurt it, I believe it would have by now.

But... By the adament beliefs of a few, there must be some tractor/mower/grass/rpm combo's that DO see a difference. All I can say is, try it and see for yourself. If you CAN'T run at a slower rpm and save fuel while still getting great results, DON'T. If you can, go for it. It works for me and has for quite a few years. That doesn't guarantee the next guy will have the same results. But to say it's yes OR no, but no MAYBE is just plain ol' wrong.

 

[RoyJackson]

My neighbor has a Ford 8N that generates 545 rpm at the pto at 1500 rpm engine (gas). My 2005 Kubota B7510HST generates 540 rpm pto at 2600 rpm engine (diesel) for my KK brush hog. The 8N purrs along when he brush hogs. My Bota screams.

That old Ford has a lot more cubic inches..probably more then double. As far as max torque...well, a lot more then your B7510.