Flail Mower Let's talk flail mowers

[JustBob]

The blades look good and th4 height is good so the other two parameters are RPM & ground speed. RPM need to be at 540 and ground speed needs to be less than 3mph (brisk walk).... IMHO.

As for the noise it should be a loud hummmm ... about 80db, but that also depends on how far you are from the flail - mine is about 6ft from my ears. Anything noise other than the hum is a mechanical issue. AGAIN IMHO.

I tried running it at 540 pto rpm and higher, ground speed was 3 mph or less(1st and 2nd gear LR)

 

[leonz]

The grass is cut, but only part of the total height. The blades during use are 2 1/2 inches from the ground, but it cuts the grass leaving it 4 to 6 tall. It cuts less and bends it over more in thick grass. The picture here is in the grass it just cut 2 days ago.


View attachment 333261

Hello justbob,

Are you sure you do not have a rear roller on it????????????????
The image of the flail mowers rotor is good enough to show you have a rear roller there.


The other issue is the belts if they are old they do not grip very well.

The mower should be run at 540 RPM with a slow grouns speed- your stating the grass is simply pushed over tells me that either the belts are wadded/shot , the engine/PTO speed is too low or the ground speed is to high.

NOW- from the photo the skids are fully raised and the mower is in the ground. The rear roller is very large in diameter as well and judging by the image you have side slicers that are too short.

The side slicers in the photo are thick not thin, are they 3 inches long in total length from the top of the knive to the bottom edge???????????

You need to reinstall the rear wheels justbob. they are there to simply prevent the corners of the mower digging into the turf as the skids are non adjustable.

 

[leonz]

The other thing that also concerns me is whether the Power Take Off rotation is right hand or left hand-if it is left hand you need a PTO reverser (which I have posted a link to on the forum here) It would explain a lot about the grass not being mowed if and only if you are operating at low ground speed and the engine speed setting is set at the 540 RPM setting or the V belts are shot.

 

[JustBob]

Hello justbob,

Are you sure you do not have a rear roller on it????????????????
The image of the flail mowers rotor is good enough to show that youy have a rear roller there.


The other issue is the belts if they are old they do not grip very well.

The mower should be run at 540 RPM with a slow grouns speed- your stating the grass is simply pushed over tells me that either the belts are wadded/shot , the engine/PTO speed is too low or the ground speed is to high.

NOW- from the photo the skids are fully raised and the mower is in the ground. The rear roller is very large in diameter as well and judging by the image you have side slicers that are too short.

The side slicers in the photo are thick not thin are they 3 inches long in total length from the top of the knive to the bottom edge???????????

You need to reinstall the rear wheels justbob. they are there to simply prevent the corners of the mower digging into the turf as the skids are non afjustable.

Read my earlier posts, it has a I installed a new rear roller and bearing kit, new belt and idler pulley. Travel speed was 3 mph and slower at minimum 540 pto rpm. Yes the knives are 3 inches total length, .093 (3/32) thick, which is thinner than any other I have seen. Maybe the previous owner installed the wrong knives?

Leonz, are you saying I should use the rear roller AND the tail wheels at the same time?

 

[leonz]

Yes Bob you need both the rear wheels and the tail wheels.

Sorry I missed the earlier posts Bob :^0

Its entirely possible they bought the wrong knives bob- these knives look exactly like the ones I have on my Mathews Lawn Genie.


EDIT: Is the flail mower level from front to back when it is on the ground bob? That would be big issue if the top link is not unthreaded enough to let it follow the ground as the skids contact the ground.

 

[IslandTractor]

The other thing that also concerns me is whether the Power Take Off rotation is right hand or left hand-if it is left hand you need a PTO reverser (which I have posted a link to on the forum here) It would explain a lot about the grass not being mowed if and only if you are operating at low ground speed and the engine speed setting is set at the 540 RPM setting or the V belts are shot.

See if the mower cuts better in reverse. If so then leonz's suspicion may be correct.

Perhaps this mower was originally set up to run in front of a tractor with front pto. That might also explain the somewhat unusual guide wheels.

 

[dieselscout80]

Are both the leading and trailing edges of those knives sharp?

If only one edge is sharp try rotating the PTO shaft by hand in the same direction that the tractor turns the PTO and watch to see if the sharp edge is doing the cutting.

 

[IslandTractor]

Are both the leading and trailing edges of those knives sharp?

If only one edge is sharp try rotating the PTO shaft by hand in the same direction that the tractor turns the PTO and watch to see if the sharp edge is doing the cutting.

Yes, both edges start out sharp. That type of knife is reversible.

 

[JustBob]

Yes Bob you need both the rear wheels and the tail wheels.

Sorry I missed the earlier posts Bob :^0

Its entirely possible they bought the wrong knives bob- these knives look exactly like the ones I have on my Mathews Lawn Genie.


EDIT: Is the flail mower level from front to back when it is on the ground bob? That would be big issue if the top link is not unthreaded enough to let it follow the ground as the skids contact the ground.

I cannot use the tail wheels, one was damaged beyond repair, that is why I purchased the roller. Yes, the mower is ran level with the roller at the highest mounting point, leaving the skids about 1.5 inches off the ground.

See if the mower cuts better in reverse. If so then leonz's suspicion may be correct.

Perhaps this mower was originally set up to run in front of a tractor with front pto. That might also explain the somewhat unusual guide wheels.

It seems to cut better going forwards, but very little difference. Which direction should the cuttershaft turn?

Are both the leading and trailing edges of those knives sharp?

If only one edge is sharp try rotating the PTO shaft by hand in the same direction that the tractor turns the PTO and watch to see if the sharp edge is doing the cutting.

The knives have only been used to cut two acres, they are still fairly sharp. A lot sharper than my lawn mower blades.

 

[Arc weld]

OK, you don't need the tail wheels and since the knives are reversible, it doesn't matter which way the rotor is spinning. Reverse rotation leaves a finer cut but you probably wouldn't notice much difference. Those are the right knives, wouldn't be surprised if they were stamped Mott. The biggest concern is that it makes a lot of noise. This is not normal. Mott's have to be run at 540 RPM and should make a turning sound almost like a big fan would, not loud and unbearable. When cutting you almost shouldn't hear it because the grass acts as a sound deaden-er. It shouldn't vibrate and should be quite smooth when running. Vibrating would indicate the rotor is unbalanced. It is highly possible that the rotor bearing(s) are shot, possibly from over or under greasing. Mott's use top of the line Sealmaster bearings and a bearing house can match them. About the only other possibility, that's extremely rare, is the rotor is bent. I only say this because way back when a stupid operator on a MF 275 with duals and with an 88" rear and both left and right hyd. Interstator wings (read heavy) got stuck and put the chain from the tandem tow truck around the rotor on the mower.:duh: After that my dad kept a spare rotor in stock.

Non Mott/Alamo belts are KNOWN to cause problems. They are specifically built for Mott/Alamo. The belt could be slipping and not allowing the rotor to turn at the proper speed. Take the belt guard off and inspect the belt, pulleys and tensioner. Maybe the tensioner bearing is binding? Leave the belt guard off to see what's happening when you're using it. Laying the grass over would indicate the rotor not turning fast enough. Could there be a problem with the gearbox? That could certainly cause a vibration and loss of speed. Last thing to check is that the PTO on the tractor is slipping or not working properly. If you can't figure it out, I'm sure Alamo would be able to offer assistance since these mowers have been around over 45 years.

 

[leonz]

I cannot use the tail wheels, one was damaged beyond repair, that is why I purchased the roller. Yes, the mower is ran level with the roller at the highest mounting point, leaving the skids about 1.5 inches off the ground.




It seems to cut better going forwards, but very little difference. Which direction should the cuttershaft turn?





The knives have only been used to cut two acres, they are still fairly sharp. A lot sharper than my lawn mower blades.

The normal state of affairs is that the flail mower rotor should be spinning towards the back of the tractor-looking at the left side of the flail mower the rotor will be spinning clockwise which permits it to carry the clippings over the rotor and throw them down to the ground.

A forward spinning flail mower rotor is typically used for highway mowing machines where if the flail mower knives and rotor will toss any object it impacts forward rather than backward towards an oncoming vehicle.


NOW if you can adjust the position of the rear roller(raise it) you should raise it up one position and then try mowing with it as the mower will create a higher pressure gradient,
meaning more suction to pull up the grass blades and aid the side slicers in slicing the grass blades and the mower will sound like a big household vacuum cleaner.

 

[JustBob]

Ok, I checked today and the belt and pto are not slipping, but the bearings are definitely bad.

The cutter shaft rotates in reverse of the wheels on the tractor...




Changing the rotation would be fairly easy if needed. I searched and couldn't find anything, are there any advantages to either forward or reverse rotation?

 

[leonz]

Ok, I checked today and the belt and pto are not slipping, but the bearings are definitely bad.

The cutter shaft rotates in reverse of the wheels on the tractor...

View attachment 333421


Changing the rotation would be fairly easy if needed. I searched and couldn't find anything, are there any advantages to either forward or reverse rotation?

You want to leave the rotation as it is bob as it is best for mowing.
If the bearings are bad as you say you have the culprit.

I would also check with an Alamo representative and ask if the rear wheels are still available and by installing the rear wheels you can remove the rear roller AND then be able to mow closer to the ground to create the proper pressure gradient/suction to mow much better after replacing the rotor bearings.

 

[Arc weld]

You NEVER remove the rear roller. The gauge wheels aren't used in place of the roller. Even with the gauge wheels, if you removed the roller and went over a hill or a mound, you could seriously damage the mower cause there'd be nothing to stop the middle part, between the gauge wheels, of the rotor from hitting the ground. Gauge wheels can help if you're turning a lot. I think the best thing you could do is get an operators manual from Alamo. You should get a real nice cut once you replace the bearings. Reverse rotation gives a finer cut. There was a sod farm up here that used an Interstator with the fine cut rotor and reverse rotation in addition to using reel mowers. I doubt you would have been able to tell the difference in cut. Your mower has the course cut rotor but will still leave a very nice cut once it's operating properly.

 

[JustBob]

I would love to get a replacement tail wheel, but the assembly for just one is $800... that's about the cost of a rear roller kit and does not include the tire! Tomorrow I am ordering new bearings and a heavier set of blades, most of my cutting will not be in grass.

Would the bolt and nut be better than the pin and carter key on the clevises? I was going to rplace those as well.

 

[IslandTractor]

I would love to get a replacement tail wheel, but the assembly for just one is $800... that's about the cost of a rear roller kit and does not include the tire! Tomorrow I am ordering new bearings and a heavier set of blades, most of my cutting will not be in grass.

Would the bolt and nut be better than the pin and carter key on the clevises? I was going to rplace those as well.

I just looked again at the photo you posted of your knives. They look to be in great condition. No nicks even. They are perhaps lighter duty but why replace them? The clevises also look fine.

 

[whirly]

Clevis pins & carter keys were OEM. I have an old Mott 72 with 92 pairs of blades and the pins/carter keys ... I just replace the carter keys whenever I change the blades. A box of carter keys is really cheap and unless you are hitting the blade roller with a lot of abrasive material the carter keys last until you need to replace or sharpen the blades.

 

[dieselscout80]

Ok, I checked today and the belt and pto are not slipping, but the bearings are definitely bad.

The cutter shaft rotates in reverse of the wheels on the tractor...

View attachment 333421


Changing the rotation would be fairly easy if needed. I searched and couldn't find anything, are there any advantages to either forward or reverse rotation?

My Ford 917 rotates the opposite of that and it does a great job of mowing. It does a go job of pulling up the grass the tractor tires pack down and then cutting it.

I have these knives.

http://www.tractorbynet.com/forums/...alk-flail-mowers-post2070762.html#post2070762

 

[JustBob]

Ok, one last question, I did not notice an oil seal on the output (pinion) shaft of the gear box. Is this parts list and diagram accurate for my model?





This is from a parts book I got from Alamo, SHD Flail (03-04) Rev 10-08
I don't have these parts from the diagram, 2, 3, 4, 7, and 9.

 

[Arc weld]

There is no such thing as a carter key! It's called a cotter pin and Mott's have a special cotter pin that is flat on one side to make it easy to bend the long leg up when putting new knives on. The flat side goes against the mount so the cotter pin won't turn when you go to bend the leg up. They used to have a tool that came when you bought a box of knives but side cutters work good. You have the right knives. I think Alamo has 3 oz and 4 oz HD knives. Your knives are like new, why change them? They are superior to Ford knives, use less power and are also self cleaning. If they encounter an obstacle, they are individually free swinging in all directions. Replacing perfectly good knives is a waste of time and money.

YOU MENTIONED YOU AREN'T CUTTING IN GRASS??? A Mott/Alamo is designed for cutting grass and WEEDS up to 1" diameter. This doesn't include small tree's. They are NOT designed for cutting brush! If you bought it for cutting brush, it is not the right machine. Cutting grass and weeds it will last you a lifetime. You need to look at the proper manual for specific machine. There have been some changes to different models over the years.