Flail Mower Let's talk flail mowers

[CADplans]

I am sorry to hear about you guys that have to work on your flail mowers,,,

On another note,
I got to run my 390 yesterday, mowing about 3 acres of pasture, into a lawn-like finish

I like to mow this time of the year, before the annuals like milkweed go to seed.

I have to be careful, a neighbor has some deteriorated high tensile fence.
Three times I have wound up 30-40 feet of that wire, always at the end of the rotor.

Thankfully, I have an oxy-acetylene torch,,, I do not have a cutter that will cut that wire,,,

 

[Steave]

Ozarks Landowner my mower (Mott 72) vibrates the mower, tractor, and me until it reaches close to PTO speed and gets all the knives slinging outward then it smoothes out nicely. When I'm mowing I have my ear protection on and tunes going but if I hit a thick patch of grass and the mower slows it will vibrate slightly and I know to raise the 3ph before I even look back to see what happened. Then it's slow down until I get out of the thicker stuff.

I'm not sure (Maybe a pro can verify) but I think most flail mowers are designed to run very close to PTO speed. Actually its about the only time I run my tractor at that speed. So when you're trying it make sure you're at the correct speed. If you have all the knives removed you shouldn't feel much if any vibration no matter what speed you run it.

Look at the bright side if you can't keep it from vibrating mount you a chair on the dang thing. :thumbsup:

 

[CADplans]

I think most flail mowers are designed to run very close to PTO speed. Actually its about the only time I run my tractor at that speed. So when you're trying it make sure you're at the correct speed. If you have all the knives removed you shouldn't feel much if any vibration no matter what speed you run it.

Look at the bright side if you can't keep it from vibrating mount you a chair on the dang thing. :thumbsup:

My JD 390 runs smooth at any speed, even at an idle.

Maybe my rotor is heavy compared to the weight of the knives??

When I engage the pto, even at an idle, there is only a small "woosh" sound of the blades spinning
and the mower itself will "torque twist" if the mower is off the ground.

It is smooth,,,,,

 

[IslandTractor]

My Caroni runs more smoothly at some RPM compared to others. I can tell when I've lost a set of knives pretty easily by change in vibration..Losing one set is sometimes hard to notice immediately but losing two is very noticeable.

 

[Steave]

My JD 390 runs smooth at any speed, even at an idle.

Maybe my rotor is heavy compared to the weight of the knives??

When I engage the pto, even at an idle, there is only a small "woosh" sound of the blades spinning
and the mower itself will "torque twist" if the mower is off the ground.

It is smooth,,,,,

Yea your JD 390 is heavier. 90.5" cutting width and mine is 72". It wouldn't have to be the JD but I'd like to have one with about a 2' offset. That would be so handy.

Mine jumps and carries on until the knives get going and when I shut it down it does it again at a certain rpm. It does have a few more knives than the JD390 but I wouldn't think that's the reason. I would lean toward the weight difference. The Mott weighs 530 lbs with the finish cut knives. It has 92 stations with 184 knives. The JD390 has 84 stations with 168 knives. Not sure how much the JD weights but would guess 900 + ??

 

[Permaculturist]

I got my new Berti TA/S 220 running today for the first time. This picture shows where I began mowing. I cut about 1.5km of ditch in under 2hrs and didn't break anything. The road looks amazing now, but you'll have to take my word for it, cause I forgot to take the 'after' pictures. Now I have quite a bit of work to do with the thinning saw and chainsaw so I can make room for the tractor on the other side of the ditches. Even though I can fit, it's too wet and I'm too heavy to drive down the bottom of the ditch cutting up the other bank. That job will have to wait for the leaves (and the temps) to drop.

I have a bunch more work to do with this Berti, and I'll make sure I film some of it.

 

[CADplans]

Yea your JD 390 is heavier. 90.5" cutting width and mine is 72". The JD390 has 84 stations with 168 knives. Not sure how much the JD weights but would guess 900 + ??

The 390 weighs about 1,200 pounds,,,

 

[Steave]

The 390 weighs about 1,200 pounds,,,

Hey I got the + right. :thumbsup: That would explain the smooth running, the heavier the better. That would be a little more than I would want to drag around though. I thought my Mott was heavy at 530 lbs. I've heard folks say they weigh 800 lbs some say 900 lbs but I weighed mine with my overhead hoist scale and it said 530 lbs I don't think the scales are too far off ??

Does your JD cut good at slow rpms or do you run it at higher rpms. I wish mine had a 6:1 ratio gearbox so I could run at a lower engine speed. My ford reaches PTO speed at 1800 engine speed but I like to run it about 1600. The gearbox on the Mott is 4:1 ratio so the rotor is turning at 2160 rpm.

 

[Steave]

My Caroni runs more smoothly at some RPM compared to others. I can tell when I've lost a set of knives pretty easily by change in vibration..Losing one set is sometimes hard to notice immediately but losing two is very noticeable.

I better knock on wood but miraculously haven't lost any knives yet. Pretty sure I'd be able to feel it if and when I do. I removed the outer sets of knives as they're extremely close to the side plates and you can see where they have rubbed before. I saved those for spares, sure hope I Never need them.

IslandTractor I appreciate all the information you've given on this thread. It's helped me learn how to use and maintain my mower. I haven't had it long but I've used it enough to know it's a keeper.:thumbsup:

 

[CADplans]

Hey I got the + right. :thumbsup: That would explain the smooth running, the heavier the better. That would be a little more than I would want to drag around though. I thought my Mott was heavy at 530 lbs. I've heard folks say they weigh 800 lbs some say 900 lbs but I weighed mine with my overhead hoist scale and it said 530 lbs I don't think the scales are too far off ??

Does your JD cut good at slow rpms or do you run it at higher rpms.

I see very little difference cutting at pto speed, or half that,,,
in grass under 2 feet tall.

I usually slow way down in turns, the 390 keeps cutting nicely.

In 3 feet plus tall grass,,, the 390 only cuts nice at full pto speed.
If I try to cut at lower pto speed, the tall grass will make the 390 chatter.

 

[Ozarks Landowner]

Didn't get a chance to work on mine today as I am having mower deck problems on my 154 cub lo boy. Gotta get that thing fixed before my yard gets too out of hand.

 

[leonz]

Ozarks Landowner my mower (Mott 72) vibrates the mower, tractor, and me until it reaches close to PTO speed and gets all the knives slinging outward then it smoothes out nicely. When I'm mowing I have my ear protection on and tunes going but if I hit a thick patch of grass and the mower slows it will vibrate slightly and I know to raise the 3ph before I even look back to see what happened. Then it's slow down until I get out of the thicker stuff.

I'm not sure (Maybe a pro can verify) but I think most flail mowers are designed to run very close to PTO speed. Actually its about the only time I run my tractor at that speed. So when you're trying it make sure you're at the correct speed. If you have all the knives removed you shouldn't feel much if any vibration no matter what speed you run it.

====================================================================

Hello Steave,

If your mower is vibrating at low speeds that is not good. All you should have is the chatter of the side slicers bouncing around until the centrifugal force created by the high speed rotation of the flail mower rotor forces them to fully extend them selves into the proper orbit around the flail mower rotor.

The low RPM shuddering/shaking indicates there is something wrong with the rotor balance or possibly a bad bearing at this point.


You also need to keep your tractor engine running your Mott at the 540 RPM engine speed as it will not work well otherwise and you will smoke belts.

 

[Steave]

leonz

Hello Steave,

If your mower is vibrating at low speeds that is not good. All you should have is the chatter of the side slicers bouncing around until the centrifugal force created by the high speed rotation of the flail mower rotor forces them to fully extend them selves into the proper orbit around the flail mower rotor.

The low RPM shuddering/shaking indicates there is something wrong with the rotor balance or possibly a bad bearing at this point.


You also need to keep your tractor engine running your Mott at the 540 RPM engine speed as it will not work well otherwise and you will smoke belts.

Thanks for the help. I let the mower come up to speed and somewhere in between slow and PTO speed is when it vibrates. Actually don't let it sit there running at idle so it might just chatter at idle speed. I'll try that next time and just see. It has new bearings but that don't mean I don't have a bad one. My mule as you call it has a 2 stage clutch and I can let it come up to speed gradually.

I appreciate the info. I'm happy with the mower and it's used mostly on field roads that receive regular cuttings and a portion of my yard not cut with a lawnmower. It does a good job.

 

[CCWKen]

If you have a hollow drum rotor like most do, you can drill a hole in it and install about two pounds of Dyna Beads. Then plug the hole afterwards. A cheap alternative is glass beads (blasting media) and talcum powder. Start the rotor up slowly to distribute the beads and it will self-balance.

DynaBeads Tire Balancing Beads

Dyna Beads is used in many antique car tires all the time. Especially the wood spoke wheels where modern wheel weights aren't large enough or too obtrusive.

 

[shaeff]

I've read (and kept up with this thread) from the beginning. It may have been answered already but I don't recall- what weight/kind of gear oil should I run in my JF 25A flail mower? I'm at the point where I'm starting to service it and I'd like to drain the likely (very) old oil out and put in some fresh. This weekend I'll be replacing the belt (shredded when I got it) and starting on knife replacement, as many are broken or bent out of shape.

 

[Fallon]

I've read (and kept up with this thread) from the beginning. It may have been answered already but I don't recall- what weight/kind of gear oil should I run in my JF 25A flail mower? I'm at the point where I'm starting to service it and I'd like to drain the likely (very) old oil out and put in some fresh. This weekend I'll be replacing the belt (shredded when I got it) and starting on knife replacement, as many are broken or bent out of shape.

Any reasonable gearbox lube. These aren't precision gears. Most run 90wt gear oil. Unless the seals are shot, then many of us add grease of some sort rather than fix the seals. I used a mix of pourable grease & 90wt rather than $75 of new seals in a flail I paid $100 for.

 

[Ozarks Landowner]

If you have a hollow drum rotor like most do, you can drill a hole in it and install about two pounds of Dyna Beads. Then plug the hole afterwards. A cheap alternative is glass beads (blasting media) and talcum powder. Start the rotor up slowly to distribute the beads and it will self-balance.

DynaBeads Tire Balancing Beads

Dyna Beads is used in many antique car tires all the time. Especially the wood spoke wheels where modern wheel weights aren't large enough or too obtrusive.

This is very interesting. Being made for tires I wonder if the beads would spread out over the length of the drum.

 

[shaeff]

Any reasonable gearbox lube. These aren't precision gears. Most run 90wt gear oil. Unless the seals are shot, then many of us add grease of some sort rather than fix the seals. I used a mix of pourable grease & 90wt rather than $75 of new seals in a flail I paid $100 for.

Very good, thank you! Right on, I'm into my 25A for $300, came with a bucket of new knives and hangers, as well as a new belt. It's got rust holes in it and is generally in rough shape, but spins pretty smoothly even with broken and missing knives it doesn't vibrate much. I only ran it for a few seconds to make sure it was worth fixing.

Thanks!

 

[Fallon]

Very good, thank you! Right on, I'm into my 25A for $300, came with a bucket of new knives and hangers, as well as a new belt. It's got rust holes in it and is generally in rough shape, but spins pretty smoothly even with broken and missing knives it doesn't vibrate much. I only ran it for a few seconds to make sure it was worth fixing.

Thanks!

I'm into mine a total of $400-500. New belts, new knives & hardware as well as a PTO shaft. Fired mine up to promptly find out why some knives were missing. Busted out the plasma cutter to cut out the trailing sections of the hood that were getting hit. Welded a crappie patch job over that hole. It was working great & way better than my new rotary cutter.

Finally changed the gearbox lube in it recently when a seal started going. The pourable grease & 90 wt is working well.

On my latest job it blew a bearing & probably mounting flange on the driven pulls. Such is life. Need to finish pulling it apart & determine what all is busted back there to order replacement parts. In the mean time I'm using the better looking but inferior new rotary cutter.

 

[Steave]

If you have a hollow drum rotor like most do, you can drill a hole in it and install about two pounds of Dyna Beads. Then plug the hole afterwards. A cheap alternative is glass beads (blasting media) and talcum powder. Start the rotor up slowly to distribute the beads and it will self-balance.

DynaBeads Tire Balancing Beads

Dyna Beads is used in many antique car tires all the time. Especially the wood spoke wheels where modern wheel weights aren't large enough or too obtrusive.

Thanks for posting this. Ozarks Landowner might could benefit from trying this. Over the road truckers used to use something like this, I guess the glass beads with powder maybe, but I had forgotten all about that. Heck it might smooth mine down a bit also. Mine smoothes somewhere close to PTO speed and runs fairly quiet for an old Mott so I just thought it was one of those things it does when picking up speed.