Why are there two different flat washers for the mower blades?

[Charrie 18]

I was mowing with my 520H which has a 48" deck (model 78360  s# 4900480) and the outer blade came off. When I came back around I was it laying there with both washers and then nut like it just doped off. I could not get the nut to thread back onto the shaft so I ordered a new shaft and nut.

 

Looking at the parts diagrams for this mower deck it shows 2 flat washers, one above and one below the blade and they have different part numbers.

From the Toro site

Upper washer

9202574
WASHER-FLAT
Replaces 920257

 

Lower washer

3256-28
WASHER-FLAT

 

So my question is which one is which and which one goes on first?

One is just a little thinner with a slightly larger OD and just a slight smaller ID.

 

Also the shaft does not have a key way so I guess the pulley just slides down over the shaft? I checked the part of the shaft where the pulley goes on and it does not appear to be tapered.so I am assuming the pulley should just slide off fairly easy or will I need a puller of some kind?

 

Thanks in advance

Charrie

[daveoman1966 3,745]

The washer ....9202574  is a VERY THIN washer between the blade and base of the spindle shaft.  

The other washer ...between the nut and blade is MUCH THICKER 

That's the diofference.

 

[Charrie 18]

Thanks Daveoman1966. This one is definitely not very much thinner then the lower one. It is hard to tell the difference if they are separated from each other. It guy we bought the 520h from said one of the blades was cutting lower then the others and he tried shimming them. How critical is it that the thinner washer be in there? 

We are will have the deck off to do this repair so we will inspect the deck to see what the problem might be. When we bough *** last summer the PO said it was just serviced and was ready to go. He mentioned that the mower deck had some rust under it but that it should still be goof for a few years.   I have seen several threads about repairing rusted decks.

[JoeM 7,871]

I often wondered about that thin washers purpose myself. Maybe it is hardened and used to prevent damage to the spindle??? Maybe it supplies more "bite" area blade to shaft??? Maybe Wheel Horse just had a bunch of extra ones and used them up???

I have seen them left out with no issues.

Not sure.

[lynnmor 7,302]

1 hour ago, TractorJunkie said:

I often wondered about that thin washers purpose myself. Maybe it is hardened and used to prevent damage to the spindle???

 

That is my thought, blades are rather crude and the surfaces are often not quite flat, so let the washer take the abuse.