Flail Mower Let's talk flail mowers

[Eagleview]

This is how a rotor is balanced , with the knives/hammers attached .

YouTube - Baler Shredder Balancing.MOV

 

[IslandTractor]

This is how a rotor is balanced , with the knives/hammers attached .

YouTube - Baler Shredder Balancing.MOV

The question is what is the advantage of such a system over one that is symmetrical and therefore inherently balanced.

 

[IslandTractor]

Thats correct but the unbalanced ones do tend to give me "bad vibrations" ...

Let's be kind to our unbalanced friends.

 

[Eagleview]

The question is what is the advantage of such a system over one that is symmetrical and therefore inherently balanced.

We will have to wait for a manufacturer to chime in and explain , they are way smarter than me and they wouldn't go to all the trouble without a reason .

There are several different rotor designs , the Europeans seem to build them like mine . The Americans appear to build them with equal rows that may not need counterweights and then there is the Double helix type that is a screw type pattern that ensures only one hammer/knife set strikes at a time , reducing horsepower demands instead of having 7 sets striking at the same time zapping horsepower and using more fuel .

 

[IslandTractor]

Caroni is an Italian brand so not all European flails are asymmetrical.

 

[rgrimsha]

I replaced the knives on my ford flail mower last year. As I did I noticed what I thought was an unbalanced hack by a previous owner. So I removed the extra knife from the unbalanced row and the mower runs smoother than ever. YMMV

 

[Eagleview]

Caroni use 4 different rotor configurations .

 

[sodamo]

OK, I also got under mine a bit. Here are the pics.
Appears to be some effort at balancing, 1- a small plate welded at one end of the shaft. 2 - 2 smallish beads about 1/3 distance the other end. Could be just sloppy welding, but the rest of the shaft is clean so these appear to be there on purpose.

As for knife weight... I don't have a scale, but I did fashion a "knife-edge" balance and my hammers are definitely heavier than the grass blades.

Overall, I consider mine to be quite tolerant. I really banged up my hammers before I replaced them. I only got a noticeable vibration if I severely damaged a hammer, note the one on top far right.

 

[Eagleview]

Thanks for going to the trouble , those small weights are what was put there at the factory to Dynamically balance the rotor with the knives they put on at that time . The replacement knives would be somewhere within the allowable weight specs so the mower should always run pretty good . The absence of any large counterweights is apparently because of the straight rows and even numbers of knives that are fitted . So I digress , some , flail mowers run straight rows of knives and some , run staggered which requires a counterweight and some run a double helix which run counterweights .

My Cabe's run a large one on each end , the Berti runs 3 smaller ones , one on each end and one in the middle and my FAE excavator mulcher runs 2 large ones on each end which is (i think) a double helix , they are all to compensate for the knife arrangement not only to take out any harmonics the rotors may have had at the factory .

 

[leonz]

Yes sir, our lawn genie has staggered mounts with spring shackles and welded balance wieghts on the rotor shell.


I think the John deere that pop had was the same way as it had a herd of grass knives in four rows.

Time for me to go to bed Iron Horse, hope all is well down under and the fosters is still good and cold; I hope the fight with the Lantana is going well;

We have had a surge of Giant HOG WEED nasty stuff) and I am sure it will be huge this year with the good growing season so far- the grapes will be two or more weeks early for harvest and the sugar beets will be ready to harvest august first to pre pile beets as the tonnage will be huge and I mean huge as they are starting the sugar refineries early because of the crop size.



leon

 

[IslandTractor]

Caroni use 4 different rotor configurations .

The popular TM1900 sold in the US by AgriSupply uses the B version which as noted is balanced

 

[KRBrouwer]

Leon, your examples actually prove that the flail knives move faster than the rotor. Consider the smaller tire analogy. In order for the smaller tire to go the same distance in a given time (miles per hour) as the larger tire the smaller tire must run at higher RPM. That is to say if the smaller tire (rotor) was running at the same RPM as the larger tire (flails) it would be traveling slower.

Likewise, the race track shows that at any given ground speed you will complete the circuit (RPM) by being in the inside lane because there is less ground to cover. To finish the race in a tie, the outside runner (flail knife) must travel faster over the ground than the runner in the inside position (rotor).

Thus the flail knife travels faster than the rotor through space even though they have identical RPM.

And, yes, we are in agreement that we all love our flails, balanced or unbalanced.:thumbsup::laughing:

IslandTractor is correct. You have two concentric circles (think doughnut), the outside of the doughnut (larger circumference) is the circle that the flail knives make and the inner hole is the circle that the rotor shaft makes. The are both making the same number of revolutions per minute. Since the circle for the knives is larger, the speed (rate of travel) of the knives is greater than the speed of the rotor.

Ken (Way too much math in graduate school)

 

[leonz]

OK so if the knife blade is traveling at 100 miles per hour it is speeding along and rotating at 8,800 feet per minute using 88 feet per minute for 1 M.P.H.

So

critical shaft speeds with distributed loads:


N= critical shaft speed

N subscript 1= critical shaft speed of shaft alone

d=diameter of shaft



Relationship of Force F, torque- tau, linear momentum-p,

and angular momentum-L in a system where rotation is constrained in one plane only.

(Forces and moments due to gravity and friction not included)

torque-tau=Radius * Force

angular momentum-L=Radius * linear momentum-p

w=load aplied in pairs

l=distance between center of bearings


total load=w

N=100 * d squared divided by l * the sqaure root of w*l

N subscript 1=100 * d divided by l squared

so if my rotor wieghs 100 pounds


N= 100* 12 * 12/48*48



N subscript 1= 100 *d /48 squared

sorry I am tired and have to stop

 

[beppington]

Nothing new here, just a pic of my dad's month-old Caroni TM1900

 

[IslandTractor]

Nothing new here, just a pic of my dad's month-old Caroni TM1900

Hey, no overflow oil stains! Did you forget to put in oil or was this before any mowing or did you just clean it up for the photo? You cannot be a member of the TM1900 club without oil stains.

 

[beppington]

Hey, no overflow oil stains! Did you forget to put in oil or was this before any mowing or did you just clean it up for the photo? You cannot be a member of the TM1900 club without oil stains.

Yeah, weird, remember how I said AgriSupply gave us a sheet telling buyers to fill the oil only to the lower level ... Well, the guy outside that was getting the mower prepped & ready to lift & put on our trailer said he was having a hard time getting the oil out, since he was trying to hurry, etc., & really made a mess, oil was all over the mower. And it's very stinky oil, as you know. My dad wiped that all up, started to empty out the "extra" oil, then decided to just let it spill out until the correct level, & clean it up as needed. So far none has spilled out ... yet, the oil is in there & above the low mark. I know his land/ grass isn't that smooth ...

 

[beppington]

Although my dad bought a new Caroni TM1900 ~5 weeks ago, & has used it to mow his lawn & fairly smooth/ under control pasture & been pleased with the results, & I mowed some of his grass with it, I still wasn't sure it's what I need for my place, since mine is a lot less under control than his. Now I'm sure ... It is!

I spent ~4 hours using his Caroni yesterday, mounted on my Kubota (we had to shorten the shaft by 2"). I mowed ~1/4-mile of sloped roadside, ~1/4-mile of unimproved driveway (had been bush hogged a month or so ago), ~an acre of grass, a couple acres of very high & thick grass, & ~an acre of previously bush-hogged-but-now-growing-back-up underbrush, & the Caroni did great! It is too cool to mow thru high, thick grass/ brush & look back to see a fine looking 6-foot wide mowed path!

I was also not sure the Caroni would provide a smooth enough looking cut on the "lawn" grassy part, but it really looks great, too. I'm a very persnickety dude, & I'm perfectly satisfied with the lawn cut the Caroni did.

I'll be buying my own first chance I get! :thumbsup:

 

[nunyabinis]

I mowed fields for 20 hours at the Hunt Club this past weekend. In many places the weeds were 8 feet tall. The Caroni didn't even moan. I cut sapplings up to 3 inches in diameter and the Caroni didn't even burp. A couple members were using their standard rotary cutters and could not believe what I was able to chew up with the Caroni. They said it looked like a giant chainsaw as it ingested those sapplings.

I then used it to mow the yard grass at the Club House and the members couldn't believe that one machine could chew trees AND mow yard grass like a finish mower.


It's an all-purpose machine. If mine flew apart today I'd buy another one tomorrow. (and if I keep chewing 3 inch sapplings I may have to make good on that) :laughing:

 

[IslandTractor]

I wouldn't suggest a steady diet of 3 inch material but the only thing I have really had trouble mulching has been rocks. Over the past three years I have had to replace about ten stations ( one clevis, two heavy duty knives and a nut and bolt = $16) and every one was due to rock strikes. Not little movable rocks but buried ten plus pound varieties. You learn the sound. The biggest rocks don't cause the most trouble as the flail just scapes up the rock and moves on. The problem rocks seem to be the ones that get partially dislodged so the flail pushes them and keeps trying to cut. The weak point is clearly the clevis which may be a safety feature.

 

[leonz]

The more I see of the bolted hangers the better I like the spring tensioned shakles on my lawn genie- the grass blades are 1.90 and the dethatching blades are 1.10 plus tax as of today so i asked them to order a complete compliment of knives today.

I would be willing to bet a cold beer on the porch that the caronis could use the the large standard spring hanger shackles on the rotors easily for even the hammer knives and cup knives.


You would have doubl;e check the mowing clearances but I bet that they would be fine for the Caroni's.


leonz:thumbsup: