Flail Mower shaft won't turn

   / Flail Mower shaft won't turn #1  

Post Carbon

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Joined
Jan 6, 2012
Messages
44
Location
Pacific NorthWest
Tractor
Kubota B7800, LA402 FEL
So I bought a brand new Del Morino Funny Top flail mower last spring 2021. Used it a bit around the place to whack blackberries and trim some light brush--not a lot of hours. Parked it for the dry parts of the summer (nothing growing) and today hooked it up to clear a bit of brush that's regrown.

It won't rotate. The tractor PTO is fine. We unhooked the driveshaft from the mower, and hand turned the connector. It turns freely clockwise with a bit of grinding at one point, and won't turn at all counter-clockwise, which is how the PTO would normally rotate it. I can't turn the knives shaft underneath by hand at all.

Before I parked it, I cleared out what I could from blackberry vines or other detritus. I've searched these forums for any advice, and haven't had any luck finding examples of seized? shafts. Anyone got any ideas? I'm new to flail mowers, so I feel like I'm really in the dark. Before I ever used it, I greased everything they said to grease.
 
   / Flail Mower shaft won't turn #2  

MadMartin

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Aug 10, 2021
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23
Location
Kentucky
Tractor
Kioti DK4710SE
you probably have vines wrapped around the ends of the shaft. Also did you grease it every use? If not pump it full of grease and rotate by hanf.
 
   / Flail Mower shaft won't turn #3  

DieselBound

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Aug 9, 2016
Messages
3,326
Location
Arlington, WA
Tractor
Kubota B7800; Kioti NX5510HC
Could you clarify what you mean when you say that you can "hand turn the connector" but not "counter-clockwise?"

Are you saying that the gearbox turns, albeit stiffly, clockwise?

Pull the belt cover off and check for obstructions.

New mower... Factory for my flail wasn't real keen on ensuring that all bolts were sufficiently tight. One or two bolts holding the rotor shaft housing end hub decided to free themselves after only about 8 hrs of runtime. I was extremely fortunate to have caught it right away. We're talking a 7' flail, a mass of about 1,200 lbs. Shaft shifted dramatically and mashed some of the re-cut knives as well as the main housing. It's possible that you could have something similar brewing (which would bind things up). I'd figure it shouldn't take much time to figure out what's wrong: just gotta take a few things apart.

Lack of grease and sitting for a bit will result in things getting pretty stove-up. I recommend greasing the heck out of things prior to parking them for a period of time: OK, it's a practice that I'm trying to get myself conditioned to do (after realizing failing to do so results in really arthritic operating of shafts and such). Ample grease means less space for water to occupy (and here in the PNW there's ample water- we got 100" of rain here last year!).
 
   / Flail Mower shaft won't turn #4  

Fallon

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Aug 25, 2013
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6,628
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Parker, CO
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Kubota L4060hstc, formerly L3200hst
Many or most flails have an overrunning clutch in the gearbox. Makes it trivial to turn the PTO shaft one way & nothing past the gearbox spins. Turn the other way & it locks up to drive things. If the flails are on the ground or there is junk wrapped up around the drum you won't turn things by hand.

Grinding is never good, but it could just be shackles or knives moving around on the drum or PTO shaft guards or belts that took a set.

Lift the flail & make sure nothing is caught up in the bearings. Grease things well. If you can't spin the mower by hand with the pto not hooked up you may have bad bearings. Not fun to replace (at least on my ancient Ford 917 flail) but not the end of the world.
 
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   / Flail Mower shaft won't turn
  • Thread Starter
#5  
OP
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Post Carbon

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Joined
Jan 6, 2012
Messages
44
Location
Pacific NorthWest
Tractor
Kubota B7800, LA402 FEL
To answer DieselBound:
> "Could you clarify what you mean when you say that you can "hand turn the connector" but not "counter-clockwise?""<
What I meant is that I can hand turn the PTO connector on the flail gearbox (we removed the shaft connecting the tractor PTO and the gearbox PTO connector). It will turn clockwise with a bit of grinding at the same point in the turn, and it will not turn at all counterclockwise, which is the direction the PTO would normally turn the flail gearbox.

>"Are you saying that the gearbox turns, albeit stiffly, clockwise?"<
It turns fairly easily (I can feel the lube) for most of the clockwise rotation, but at one point I can hear and feel a short grinding in the gearbox, just briefly. That seems weird to me. I checked gear oil before using when new, and checked it again with this problem, and there's plenty of gear oil.

>"Pull the belt cover off and check for obstructions."<
I did this just to see, and there are no obstructions. I even loosened the tensioner and was hoping to take off the belts so I could test if it's a gearbox thing or a knives shaft thing. BUT, the belts are still super tight and I can't get them off, and Pg 11 of the owner's manual is no help because it just says 'remove the belts'. Yeah, thanks Sherlock, I'm looking into the manual for help to remove the belts. And I can't rotate the belts off because, yes, I can't rotate anything right now.....

Am I going to have to take this thing all apart? Ugh. To do that, do you flip it over on its back like a turtle? Or hang it from the rafters? I'd hate for this thing to fall on me.

PCP
 
   / Flail Mower shaft won't turn #6  

Jack Yuan

Gold Member
Joined
Apr 14, 2013
Messages
452
Location
Changzhou, JiangSu, China
Tractor
Jinma 504, Jinma 904, YTO X1804
The bearing on the rotor shaft end was burnt, need place new bearing.

One of the possible reason is that not enough grease in the bearing when mowing, over heat and burnt.
 
 
 
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