Re: COZY: Belleville Washer Stacks

Marc J. Zeitlin

Palmer Reising wrote:

Do you see any problem with using an eight (8) Belleville washer stack on the 1/2 inch Propeller bolts on a Cozy III with an O-360...

Problem? No. Completely unnecessary and heavy? Yes. Most people using bellevilles run either two or four. With 1/2" bolts, almost all use four. Eight, as they say, is right out.
or would you suggest buying new bolts and using a four or six stack?

New bolts and a stack of four.
Catto Propellers didn't seem to have any objections since they sent 24 additional Belleville washers.

They sent new washers because you apparently bought a new prop, and Craig is now sending bellevilles BY DEFAULT with every new prop, as he's seen the light and caught the religion :-). He doesn't know what you've already got on your airplane.
Also, should I use a wide area washer against the crush plate with the stack. One wasn't there in the original installation (see photograph).

I always put an AN970 washer against the crushplate to protect the AL crushplate from damage from the steel belleville washer edges.

What would the proper configuration of all washers (thin, Belleville, medium and wide area) in each stack of eight be?

If you were going to use a stack of eight, you'd stack them the same way you'd stack four, but four groups of two opposing, rather than two groups of two opposing. This way, the force stays the same. If you're not familiar with the installation of Bellevilles, I'd suggest reading the information provided by Craig with the prop (if he sent something, which I assume he did), or Gary Hertzler's instructions for using Bellevilles, or go straight to the source and read the instructions at:

HOWEVER, my instructions are generic - for Hertzler or Catto props, USE THE MFG'S INSTRUCTIONS FOR BELLEVILLE INSTALLATION.

I'm installing a new Catto Three-Bladed Propeller and the hub is around 92 millimeters thick. The original Three-Bladed Catto propeller's hub is around 116 millimeters thick.

You will need shorter bolts - apparently, about an inch shorter. Get shorter bolts.
However, if I also use the wide area washer against the crush plate as shown in the PDF document about how to keep a wooden propeller on an aircraft with less work, I could gain about two threads more before bottoming out. Thus, I would have around seven threads before bottoming out.

Just get 1" shorter bolts and use four bellevilles/bolt.

Marc J. Zeitlin                      marc_zeitlin@...
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