Flail Mower Flail Mower issues?

[JackMentink]

I recently bought a flail mower that when I got it home and put all the blades on, and I spun it up to speed, I realized the blades hit the metal bonnet under the mower. In looking at it I realized the blades are factory blades, so they should not be the problem. I'm thinking it is either the bearings are bad or the cutter shaft is bent.

I took enough of the blades off to where I can spin it, and most of the ones hitting are near the middle and the pulley end. I watched the cutter shaft and it does not appear to wobble when it goes around.

I also took and tried to move the ends of the shaft to check the bearings and they don't really wiggle or move.

I am at a loss, any body have any ideas? The unit is a 88" heavy duty Alamo flail with brush blades.

 

[gwdixon]

I have an old Alamo flail mower. It is in storage over winter, but if my memory works correctly, there is an adjustment to the bearings that influences where the shaft runs.

Check closely to see if there is an adjustment bolt.

With no bonnet damage and the shaft being straight there is no reason the flails should hit the bonnet. That is, as long as the blades that you put on were designed for the mower. Double check that fact to make sure. There are many different styles and attachment choices.

 

[JackMentink]

Thanks for that thought on the adjustment for the bearings. I will look into the adjustment more closely to see if it is adjustable. The flails are the correct ones as I have checked them verses the manual for the unit which I have.

 

[greg_g]

The flails are the correct ones as I have checked them verses the manual for the unit which I have.

Well, I'm sure more than one type of knife (flail) was made for Alamos. Depending on what I want to cut, there are at least 3 types for my Jacobsen. There's the extra HD knivese that road crews use, a least one kind of brush knife, and at least one type of grass knife. Not that you shouldn't check on the adjustable bearing angle. But perhaps there were different shrouds offered that were to be used with a specific type knife. And check the sides of the housing for a curved series of holes. If yours is like mine, there are (at least) three per side. They're the coarse height of cut holes, and represent different angular relationships between the ground contact roller and the spinning knives. It's (remotely) possible they could alter the distance between the knives and the shroud as well.

//greg//

 

[JackMentink]

I've spent some time today on the fail mower and checked everything. There is no adjustment for the bearings of the cutter shaft or the bonnet as its welded solid in place. Does not appear to wobble, and I took the drive belt off and I can't budge the shaft (as far as play in the bearings) May be i will try all new flails and see if it makes a differece. They are only 72 cents a piece from flail master, so I figure I will give it a try.

 

[Eagleview]

Failing having a bow in the hood , it must be that at least some of the knives are too long . Measure from the rotor to the end of each of the blades when hanging straight . I'm sure the long ones will stand out from the rest . If this is the case , you will need to probably buy a full set of new ones for clearance and to keep the rotor shaft in balance . Even a slight vibration will cause fatique cracking in the panels of a flail mower .

 

[JackMentink]

Just to let everyone Know, I have solved the issue with my alamo super heavy duty 88 and the blades hitting the metal bonnet underneath.

I looked at the bearings and the bonnet to see if they had adjustments and the did not. The shaft does not appear bent. The unit is well used and has some wear.

The only thing I can figure out is that the wear has caused the little ears that hold the clevises to wear some and made the holes a little larger and possible some deformation on some of the clevises and the metal bonnet underneath.

So I ordered all new knives and got the regular duty knives instead of heavy duty. They are about .120 think instead of .192 and are stamp material instead of forged. I actually slightly bent each blade a little more. (Each blade is at a 210 degree angle and there are two hung back to back to form a Y). I changed the angle to on each blade to about 240 degrees so when you hang the two down on the clevis they are closer to a T than a Y. There is now adequate clearance on the bonnet.

I put them all on and fired it up and it runs and cuts great. I bought 90 Flail Blades from Flail master for $71.40 including shipping. That cost made the flail go, from a bad purchase on a useless piece of equipment to a good purchase on a very useful mower.

 

[Eagleview]

How did you bend the blades without fracturing the metal ?

 

[JackMentink]

How did you bend the blades without fracturing the metal ?

I just put each one in a Bench vise and bent them slightly with an adjustable wrench. They are actually made of Spring steel (per Flail master ) so they bend pretty easy. the bend is not a tight bend but a radius gradual bend that I just bent a little more. We will see how they do. I mowed about an acre but the grass hasn't really started to grow here yet (in Missouri) so I didn't actually cut a whole lot.