Flail Mower Correct PTO shaft for ditch flail mower?

[3Lfarms]

Last year I bought a Berti flail from the city and cleaned it up and painted it to match my LS. It’s a 60 hp tractor and Berti recommend 60hp minimum. I suspect their 60 hp recommendation is due more to the weight than the power requirements. The mower works great and tractor handles it fine.

The shaft that came with it is the lemon shaped euro style, but is not a CV style and doesn’t have a slip clutch or shear bolts. The outer shaft section is slightly bent so it takes about 100lbs of force to collapse and extend.

The shaft as is, vibrates a bit. I’m sure most of it is due to the bend, but I know U-joints cause a speed-up/slow-down. Do the U joints running at a steep angle when the mower is extended cause a vibration and would a CV shaft eliminate that vibration? I have a feeling that the mass of the flail rotor resists that acceleration/deceleration and makes the tractor absorb those forces causing a vibration felt in the seat, kind of like a rear tire out of balance on a car.

The joints don’t have any slop. The flail uses 4 belts and they are tight enough that when it found some barbed wire it really made the tractor grunt until I shut the PTO off.

I’m trying to figure out if I should just have this shaft straightened and maybe replace the U-joints or if I should replace it with a new Series 6 CV shaft with a slip clutch like this:
CV6 1-3/8" 6 Spline x 1-3/8" 6 Spline PTO Shaft | Agri Supply 19796

 

[leonz]

If you can have it straightened providing only if they can balance it as well

otherwise replace it and purchase new plastic bell ends to replace the ones that
are shot on the gearbox and the yoke on the end of the shaft.

It may be simpler to just purchase a new shaft as long as the new shaft is cut to the proper length with the three point hitch elevated all the way up to assure it does not bind up when running.

It sounds like this is exactly what happened with this mower and PTO shaft was bent slightly and it was not mentioned by the operator and corrected by the maintenance shop.

 

[leonz]

If you can have it straightened providing only if they can balance it as well

otherwise replace it and purchase new plastic bell ends to replace the ones that
are shot on the gearbox and the yoke on the end of the shaft.

It may be simpler to just purchase a new shaft as long as the new shaft is cut to the proper length with the three point hitch elevated all the way up to assure it does not bind up when running.

It sounds like this is exactly what happened with this mower and PTO shaft was bent slightly and it was not mentioned by the operator and corrected by the maintenance shop.

AH, now I see that you replaced the PTO yoke bells so you do not have to mess with them.

 

[leonz]

double post GRRRRR

 

[leonz]

Hello 3Lfarms,

I want to welcome you as the newest member of the of the "Flail Mower Nations" from the great State of Utah.

LeonZ

 

[leonz]

The Geometry of the U joints/propeller shafts allow the machines to operate with no vibration at all whether the mower is operating at an angle below horizontal or fully vertical with the mower raised fully.
It sounds like you need a new unit as the crosses/ yoke bearings are also very stressed and probably damaged as well. Better to replace it with a complete shaft from Berti or a Berti equivalent shaft of the exact extended and compressed length.

A berti dealer will be able to get the right PTO shaft or recommend an equivalent if the dealer is not nearby.