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New bearings for the mower deck

Posted: Tue Mar 09, 2021 1:47 pm
by Eugen
Hi all,
I want to restore the mower deck on my 446. My understanding is that Z5904-rst is a direct replacement. Are 6 bearings enough for one deck?

I got my watch on this

https://www.ebay.ca/itm/123555619078

Re: New bearings for the mower deck

Posted: Tue Mar 09, 2021 10:27 pm
by Eugen
OK, I was just being lazy. Off I go look at the manual.
casemowerparts1.png
casemowerparts1.png
So, according to the second page, there are 6 units of item 2, two bearings per spindle, Case part C28971. If you do a search for it you end up with cross reference: Z5904-RST
z5904rst.jpg

Re: New bearings for the mower deck

Posted: Tue Mar 09, 2021 11:20 pm
by Spike188
I have tried to find a old order for replacing those bearings. I have purchased replacement Fafner or NTN bearings but can not find the part number. An bearing listed as an Ag bearing is a slow turning bearing with very loose tolerances. I fear those are no name low cost bearings as they do not list the "C" rating. C is the tolerance class of the bearing.

Looking at the spec's on NTN 204BBAR is what I used. These are sealed and are not greaseable.

NTN 204BBAR Radial/Deep Groove Ball Bearing - Round Bore, 0.7504 in ID, 1.7805 in OD, 0.6100 in Width, Double Sealed, C1 Internal Clearance

This is the same bearing size as the 204BBAR bearing but requires oil or grease and will run at speeds of 16000RPM. PEER Bearing Z9504-RST-C3 Radial/Deep Groove Ball Bearing - Round Bore, 0.7504 in ID, 1.7805 in OD, 0.6100 in Width, One Nitrile Contact Seal

With bearings putting the right seal and tolerance rating is key to the life of the repair.

Spike

Re: New bearings for the mower deck

Posted: Wed Mar 10, 2021 10:27 am
by Eugen
Mr Spike, you're getting very technical here, I like it. :D

If I understand you well, you're saying that a low cost bearing like the one I pointed to, the Z5904-RST, has a C0/CN clearance if unmarked, while the NTN bearing has C1 internal clearance, and I should prefer to install the bearing with C1 internal clearance.