GL: Cutless bearing

[LRZeitlin at aol.com]

In a message dated 1/16/08 12:00:40 AM, great-loop-request at lists.samurai.com 
writes:


> There are no dictionary entries for cutless bearing, but bearing is spelled
> correctly.
> 
> I am still at a loss.
> 
> 

Elaine,

The correct name for a water lubricated rubber bearing is "Cutless." It is, 
in fact a trade name used by the original manufacturer of these bearings. I 
believe it was the Goodyear rubber company that introduced them in the '20s 
(although I could be wrong - the little grey memory cells aren't what they used to 
be).

Wet rubber has a very low coefficient of friction against metal. The bearings 
were designed to replace metal and lignum vitae bearings and to resist cuts 
by sand particles. The flutes in the rubber entrap a layer of water and when 
the shaft is turning at a relatively high speed it is hydronamically supported.

Patents on these bearings have long since expired. Other manufacturers 
employed the name cutlass to avoid infringing on the original trademark. Either 
useage is correct today. The name cutless seems to have passed into the public 
domain like Kleenex.

Here is a blurb from Duramax, one of the current manufacturers of these 
bearings:

When used in propeller shaft housing, the cutless bearing provides a 
structural support with built-in resilience that allows the bearing to yield in 
sympathy with the bending of the boats structure and thus prevents shaft bearing 
misalignment or shaft wear. The bearing also reduces vibration and the volume of 
noise being transmitted into the boat. It also absorbs shock and has an 
advantage of being almost maintenance free. 

The name cutless is derived from the ability of such bearings to pass 
abrasive materials such as sand and marine organisms across its surface and into the 
flushing grooves. These abrasive particles do not embed into the bearing 
surface and cause little cutting and wearing of the shaft. 

Larry Z


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