Kubota Mower Decks - blade attachment (not splined or keyed)

[mshumack]

I'm close to buying a BX70 series with 60" deck. I have been researching for a while, and watching owner posted YouTube videos.
I came across a video https://www.youtube.com/watch?v=zcogoonHEhc showing mower blade replacement (tips, etc.) but what I though was odd about the Kubota mower/blade setup is that the blades are not splined or keyed to the spindle. Only the friction of a beveled washer keeps the blade from spinning on the spindle. So torqueing the blade retainer bolt is important.

I have a smaller 20hp 42" deck lawn tractor now and the blades are splined to the spindles - so if the blade hits something un-cutable or real thick, the drive belt slips to protect against breakage. On some Alamo batwing mowers I have worked on, the blades are keyed to the spindles. I don't have much hands-on experience with anything between the small lawn tractors and the big batwing mowers so I'm curious what is the norm.

Is it normal for smaller tractors (BX size) to use this "bevel washer" style mounting method - or is this something unique to Kubota?
And how well does it work?

In the video the blade had been spinning/slipping sop there where a few extra parts to install (due to blade slippage) with the blade change, and the mechanic said to always replace the bevel washer.

 

[davesl708]

The beveled washers protect the spindles and blades on impact with a stump or other obstruction.
My BX is 13 years old and I just replaced the washers for the first time (1350hrs) the cost was $8.

Having found a 4" high stump in tall grass cutting at 3.5" the washers worked. No damage to the mower deck.

 

[Baby Grand]

The beveled washers protect the spindles and blades on impact with a stump or other obstruction.
My BX is 13 years old and I just replaced the washers for the first time (1350hrs) the cost was $8.

Having found a 4" high stump in tall grass cutting at 3.5" the washers worked. No damage to the mower deck.

^ Exactly.
Sweet-ums found an old lally column with our G5200 (25 or so years old & ? hours).
The blade had a healthy gouge on the cutting edge, and the lally column was also gouged, but no damage to the drive line.
Thanks for bringing this up, by the way - I should probably get a fresh set of (Bellville) washers for the annual end of the season deck cleaning & tune-up.
-Jim

 

[mshumack]

Thanks for your reply.

 

[JOHNTHOMAS]

Noticed I was missing cutting grass with one blade on my F3680 three blade 72" deck after a year plus of use. One blade was free spinning. Raised deck and replaced one washer, retightened and worked perfect every since. Probably just tightening it would have fixed it.