Mower Vebration

37chief · Jun 4, 2014

When ever my flail mower gets a vibration, it means some blades have been knocked off. Yesterday I got a vibration. No blades missing. It isn't so bad at times, and is mostly when the mower is up. I can't find anything wrong. The universal is fairly tight in the cups, but there is some up, and down in the universal bearing cross shaft. Will a universal joint with some slop cause a vibration? The shaft is not straight back, but is a fairly good angle. The mower has been in operation for at least 5 years. Never had this problem before. Any thoughts on what other problem may cause a vivration? Stan

rrlund · Jun 4, 2014

Is there grass caked up on any of the flails? That'll throw it out of balance too.

Wheatfarmer · Jun 4, 2014

Becareful but see if a U-joit has excess heat after running. Might have one or more cups dragging.

RickieBlue · Jun 4, 2014

Is the orientation (phasing) of the drive shaft yokes correct?

ShadetreeRet · Jun 4, 2014

A worn universal joint is tricky to nail down. They can be reasonably tight when checked by hand, but still have enough wear to make them vibrate at speed. I once had a car that I had to replace the front universal about every six months. I always knew when because it would start vibrating at road speeds. I think I know what the problem was, now, but I did not figure it out then.

Anonymous-0 · Jun 4, 2014

Are you lifting it higher than normal? Bad u-joints, a bad bearing and/or a bent cutter shaft will cause a vibration. When my dad sold Mott's, he kept a spare cutter shaft in stock because a customer got an MF275 with a 3 gang Interstator stuck. It was a heavy unit with the 2 hyd. side units and the 88" rear flail. Don't know if it was the operator or the tow truck driver but they wrapped the chain to pull it out around the cutter shaft. Can't fix stupid!

BushogPapa · Jun 4, 2014

That is my guess.. the open link where each blade attaches catches a wad and eventually throws off.
I consider that normal..
A missing blade will cause a more noticeable vibration...

Ron.

Eldon (WA) · Jun 4, 2014

I bought one years ago at an auction...shook like a SOB when I tried using it...it is still sitting in the weeds. I'm not a big fan of flails. Give me a brush hog any day.

MarkB_MI · Jun 5, 2014

I can't imagine the drive shaft developing a sudden vibration. But if it gets worse the greater the drive shaft angle, that sure indicates a u-joint problem.

Another possibility would be a bent cutter shaft. You would have to smack something really hard to bend the cutter shaft, and you'd almost certainly lose a few knives.

I would remove the drive belt and see if the vibration goes away. If it doesn't, then you know the cutter is OK. With the belt off, you should also be able to feel any roughness in the drive line. Hopefully it's nothing too expensive.

Traditional Farmer · Jun 5, 2014

Around here the Vineyards are paying $5,000 an acre and more to have have wildflowers planted, then in the late Fall they have to be cut with a flail mower so the seed will be scattered evenly But as you say most flail mowers have a certain amount of vibration

El Toro · Jun 5, 2014

Check the blades to see if any of them are bent. Hal

Mower Vebration

37chief

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rrlund

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Wheatfarmer

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RickieBlue

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ShadetreeRet

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Anonymous-0

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BushogPapa

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Eldon (WA)

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MarkB_MI

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Traditional Farmer

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El Toro

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