Mott 72 Flail Mower sparking and throwing belt

[rgr33]

I agree with above posters. First thing I would look at is whether bearings are installed correctly.
Second thing is possibly a bent shaft.
I wonder if a driveline shop could check that out got you.

I have a really old Mott 60 inch that has been used hard every year, it does not have those kind of vibrations.

 

[PanarchyMills]

Thanks for the replies,
When the bearings go on these things, am I looking for play if I grab the ends of the rotor and yank it back and forth? Or is it more subtle and requires pulling the bearings and doing a visual/feel inspection? I'll hook up a magnetic indicator today and see if the rotor is bent. I think y'all are right about the rotor or bearings being the most likely culprit so I'll give those a good once over when I head to the field

 

[Locoweed]

If you raise the mower so it is about a foot off the ground does the problem disappear?

 

[TractorNoob85]

It might be worth taking the knives off and running the mower up in RPM to see if the drum rotates smoothly.

 

[PanarchyMills]

The problem occurred at all heights but seemed to disappear once I advanced into grass, but then the belt would jump off before I could get to full throttle. Not sure if the belt jumped off because of all the vibration, or if because the idle spring seems a little tired. I think I'll shorten the spring to try and re-tension it. The belt is old but seems ok. If I place another order I'll get a new belt...

 

[leonz]

Thanks for the replies,
When the bearings go on these things, am I looking for play if I grab the ends of the rotor and yank it back and forth? Or is it more subtle and requires pulling the bearings and doing a visual/feel inspection? I'll hook up a magnetic indicator today and see if the rotor is bent. I think y'all are right about the rotor or bearings being the most likely culprit so I'll give those a good once over when I head to the field.

If flail mower rotor bearings fail the knives will hit the
flail mower rotor shroud and wake up the dead.

If the one bearing is bad they both need to be replaced.

The Mott flail mower you have has no rear roller and that
is why the rear wheels are adjusted with the hand crank
worm gear to create the desired cutting height.

If the flail mower rotor is bent as I suspect it is because of the
vibration you have to decide if you want to replace it along with
new bearings as it will last for many decades when the repair is
done and the hand crank and worm will make adjusting the height
of cut very easy to do.

As I said earlier the rear wheel shaft cross shaft is damaged and the
cross shaft mating with wheel hub is bent.

 

[PanarchyMills]

Just got back from the field and it appears to be a bent cutter shaft. I checked with a magnet indicator and it was out at least 1/4" in the center. so I pulled the cutter shaft and I'm going to try and straighten it in the shop. Any tips are appreciated.

The bearings had no slop before I pulled the shaft and inspection after pulling the bearings shows no damage or play. I might get some replacements because it seems an easy swap but I need to get up and running quick as possible to get this field mowed...

If by rear wheel shaft cross shaft you mean the shaft between the pto gearbox and the first drive pulley, that does not appear to be bent. The pulleys appear aligned (idler pulled up out of the way in the photo)

 

[John0829]

If your rotor is out of round by a 1/4" or more you have found your problem.

 

[camshawn]

I would replace the bearing if they are a reasonable price since you have it all apart. They have taken some beating at this point.

 

[leonz]

It would be much simpler to take the flail mower rotor to a drive line shop as they will have a high speed balancer and the press to correct the out of round condition which is what you need.