John,
I think the grease performance might be influenced by such factors as ambient
humidity, temperature, dust in the shack, as well as age and use.
What happens in the grease failures, is that the grease dries out. That is,
the volatile solvent like components evaporate, and the remainder becomes the
gunk that traps any dirt or dust and that leads to the symptoms well known to
the Ten Tec PTO long time users.
Certainly heat drives off the lighter compounds, but very dry shack conditions
might contribute as well. I notice you are from FL, where the humidity might
be higher than other areas, lessening evaporation of volatile solvents. But,
that might also depend on whether you keep your shack air conditioned at a
very cool, and thus dry, temperature.
Perhaps, the grease that was used in your particular unit had a higher
percentage of volatile components that liquify the material. Thus, it has
been slower to lose its new grease qualities. Maybe the lack of use has
caused a film of hardened material that kept the inner grease from evaporating
the volatiles, yet it breaks free when you use it without symptoms of drying.
The choice of lubricants is a fascinating study. I have worked with large,
multitracked tape recorders for years, and the grease issue makes a big
difference in the performance of older design recorders as to speed flutter.
What you see in the PTO symptoms described by long time Ten Tec owners, is a
very slow speed flutter effect caused by the hardened grease in the PTO drive.
On large recorders, we have had good luck on regreasing open ball bearing
races with silicone ball bearing grease which is good for a wide latitude in
temperature. I wonder if any PTO rebuilders have tried to use such greases?
I gather the kits from Ten Tec have a non silicone grease, in that the
greasing needs to be redone periodically. The high temperature silicone
greases last indefinitely, but of course might affect some materials like
plastics. Thus, I cannot say it would be better for this application.
Good continued luck with your PTO,
Stuart K5KVH
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