Chasing down a vibration in Woods brush mower

[MESSMAKER]

My 3 year old Brushbull has picked up a good bit of vibration as the RPMs go up. I have checked the PTO shaft and blades and they seem OK. I found that one of the bolts holding down the gearbox was not tight, but I took care of that. I suspected that Maybe I bent an output shaft. I have run cutters for decades and never had this happen. I have watched the rotation of the blades but I am not sure I can trust my eyes. Anyone have any ideas?

 

[Midniteoyl]

Output shaft bearings?

Home

Shop Parts Online

store.germanbliss.com

 

[rademamj1]

Mine (BB60.50) only incured vibrations after the blades hit serious metal debris mowing along side the Interstate, and slightly bent a blade. It was just a minor deformation, barely noticeable, but at 15,000 rpm, it was enough to create vibrations. I ordered both new blades and bearings from German Bliss, but the blade replacement eliminated the vibrations. I now have a set of backup bearings just in case.

 

[RickB]

15000 rpm? Must be one of those high speed BB's.

 

[Tinhack]

Yeah, that thing must sound like a jet engine. 15,000 rpm!

 

[rademamj1]

Yikes....your right. In the cutter specs, its 15,000 fpm on the blade, not the rpm.

 

[beckmurph]

On my BB48x the welds that connected the crossbar to the blade pan broke.

Replaced the blade pan and cured my vibration.

 

[MESSMAKER]

I guess it could be the blade pan. It is dented but in one piece.
New blades are $175. What is the cost on the blade pan?

 

[beckmurph]

I don’t remember the cost exactly, but it was around $200

I have replaced 2 blades because they broke. Rocks, stumps, logs and other things I have hit with this cutter.

But, the condition of the blades have not caused any vibrations.

Loose gear box and broken welds on the blade have caused vibrations.

 

[3gunr]

Make sure your blades are swinging freely. If mine bottom out or get any grass in between the pan and blades it will shake like crazy. I usually sray some lube up there and swing them by hand to loosen them up. This has happened on al 3 of my cutters over the yrs.