Flail mower shaft

I was the lucky bidder on a five foot Bush Hog flail mower a couple weeks
ago. Well, I got it up and running today and found out why. The main shaft
is bent. It looks to be about a quarter inch out by eye. The shaft is about
66 inches long and hollow (like an auto drive shaft) It has to run between
21 and 22 hundred RPM. I haven't got the tooling to straighten it myself, so
I'll take it to somebody. Does anyone have any idea what the "straightrness"
has to be for this thing to be vibration free at speed? Within .005" ? .001"
Thanks for any opinions
Also, anybody with experience with flail mowers have any operating and
maintenence hints ( apart from "don't hit big hard stuff.").
This machine looks like it ought to have wheels on the front edge to set the
cutting height.
John
Reply to
John Hall
Loading thread data ...
Use a hydraulic press to get it straight as you can. I don't have a spec. but its not critical, maybe 0.100 in. More important is to re-balance it after you're done. I took mine to a place that does this, but I think a static balancing would most likely suffice.
Most flail mowers either use the tractor three point or a hydraulic cylinder to adjust height and have only back tires for following the terrain.
As to keeping it straight; avoid huge tree stumps, cement blocks and especially steel fence posts. I've tried all three.
A big cause of out-of-balance is a missing hammer, that might be all you have wrong now.
Karl
"straightrness"
Reply to
Karl Townsend
"John Hall" wrote in news:jXLZc.118768$ snipped-for-privacy@ursa-nb00s0.nbnet.nb.ca:
I assume you are talking about a rotary mower. 0.005 should be sufficient for the driveshaft straightness, probably 0.050 would work. You sure the shaft speed is 2200? Most PTO are run at 850 iirc (~1850 motor RPM). Basically, you can mow anything the tractor will ride down (*G*), trees included. If you are mowing grass, keep the blades somewhat sharp. Aquire a spare rear wheel and boom if you have wooded areas on your property, as you will, at some time in the future, bend the whiz out of it against a tree. IF your tractor does not have a clutchable PTO, make sure you get a slip-clutch adapter for your pto. I would also suggest a handful of shear pins in the tool tray on the tractor.
Reply to
Anthony
No this is a flail mower which I got to replace the rotary mower for straight mowing. The flail shaft speed works out to 2121 RPM at 540 RPM PTO speed.
Been there, done that, replaced the big pricey gears and bearings.
If you are mowing grass, keep the blades somewhat sharp.
The flail mower has the advantage of being somewhat off set, which is an advantage in our apple orchard. Also, I don't think it will windrow the clippings as much as the rotary cutter does.
Reply to
John Hall
needs a bigger press than I have.
I'm told there's a shop a few miles up the road that does drive shaft work . I'm guessing they could both straighten and balance for not a whole lot of money.
I'll bear that in mind. I intend to use it in our orchard which is clean.
Some are pretty battered, but all are there. they are light steel stampings, not very heavy.
John
Reply to
John Hall
Keep body parts out from under! Seriously though, I have seen short lengths of chain welded to the shroud all round to help slow and deflect downward ejectiles (ejected projectiles), you have to be careful that the chains are not able to reach the blades. Gerry :-)} London, Canada
Reply to
Gerald Miller
Are you talking the shaft from the PTO output to the mower or the shaft that runs along the top of the flail mower?? My flail mower (5ft) has an input shaft speed of 540RPM which is standard PTO speed. There are some bigger implements (my 450C track loader is one) that has a 1000RPM PTO speed. Something spinning 2200rpm is going to have to be true and balanced or you will be replacing bearings and such. Personally I don't use my flail mower much (hardly ever), it came with one of my diesel tractors and I think it does a horrible job of cutting grass.
tim
Reply to
TSJABS
I have the five foot Bush Hog flail mower also... Great for cutting brush... I don;t spin my mower near so fast... Watch out for 50 ft nylon ropes in the grass... They will scare the heck right out of you...
Reply to
Kevin Beitz
From what all I know about flails they are ore in tune to finish type mowing than rough cutting..........and they throw grass clippings out the back with little to no windrows really.
Take the shaft to a driveshaft specialist, who can straighten it and it won;t cost you a fortune either. Its a pretty straight forward process they use here in town, heat and cold applied at just the right places.
I assume your talking about the higher speed shaft that goes between the drum drive and the gear box and not the PTO shaft itself!
If its a PTO shaft I would not even fool with it as you can get individual parts to fix them like the inner shafts, outer tubes yokes etc at most any ag supply house. Visit my website:
formatting link
expressed are those of my wife, I had no input whatsoever. Remove "nospam" from email addy.
Reply to
Roy
Orchard???
I grow apples for a living, didn't know there was another grower nut on this NG.
I use the flail mower in the spring to chop up prunings. Its hard on it but does the job. I take three passes, the first pass with the unit six inches off the ground, second at two inches, and third scalping in spots. When a two or three inch limb gets wound around the flails it will tear a bunch of hammers loose, I try to get these drug out of the orchard after the first pass.
Karl
Reply to
Karl Townsend
An old barb wire fence is even worse. Of course, it does clean that old fence up in a hurry, at least until you drag a steel fence post in it.
Karl
Reply to
Karl Townsend

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.