"Jeff Liebermann" wrote in message
...
On Sun, 21 Sep 2014 15:49:56 -1000, "John Keiser"
wrote:

I see replacement pinon gears in common Intermatic lamp timers was
discussed in 2005. A more current model [TN711] and drive motor [WG2030]
uses a pinon gear that has readily crumbled [in the heat and humidity of
Hawaii, anyway]. The remnants are a golden, waxy color.
Poor quality nylon?
The gear train is hard plastic. The gear train works fine.
My question, for curiosity's sake, is why would the pinon gear be made of
such soft/poor/fragile material?

Let me guess... you're using it to run a swimming pool chlorination
system? Of course, I discovered this that hard way. Nylon is
destroyed by strong aqueous chlorine compounds.
See chemical compatibility charts at:
http://www.plasticsintl.com/plastics_chemical_resistence_chart.html

Another possibility is LOW humidity, as in a refrigerator. When Nylon
6/6 is molded, it is stiff, hard, and brittle. In order to give it
some flexibility and resiliance, it is given a water bath. Nylon is
hydroscopic

That's hy - g - roscopic, Jeff ... d;-)

Arfa