The recent posting on rebuilding a Corsair PTO multiple times to find that
polishing the shaft finally cured warble, makes me wonder what is the
viscosity of the "Red Grease"?
Is it prone to thinning with friction, and working out of the bearing-shaft
interface where it is needed in a viscous state to take up play?
If that is the case, or if no one knows what viscosity of grease it is, (which
clearly does not work indefinitely), I would suggest someone might try Dow
Corning type 44 silicone grease. It is medium consistency, "a heat stable
silicone grease for anti-friction bearings."
"---operating temperature range of -40 degrees F to +400 degrees F. For use
in bearings operating under light to moderate loads. DN values
150,000 to 200,000." Certainly, this temperature wide range would cover all
usual uses of Ten Tec PTO's! I have used this in relubing open metric ball
bearing races on precision Instrumentation Tape Recorders since 1970, and have
never had any problems with bearing play once the Silicone 44 was in use.
Before, the factory grease would work out of the bearings, and noise and
increased capstan speed error would be observed. Actually, one could say
there was increased "jitter" which was akin to the PTO warble. I think the
brass and such in the Ten Tec PTOs should work with the silicone grease
without any problems. I would keep it off plastic surfaces, and yourself, as
it is a messy product. I used wooden tongue depressors, or Q tip sticks to
work the grease into bearing races we rebuilt, or installed. I had a stable
of 5 Ampex 1800/1900 recorders all with large metric main capstan bearings
whose grease would work out with heat, necessitating a repacking process akin
to doing a car's front wheel bearings.
After discovering this grease worked so well, I have used it whenever a medium
grease has been needed for shaft bearing lubrication with good results. But
the recorder use, was the most similar to the warble of PTO problem, thus my
belief this material would work. It should be available from industrial
supply houses, maybe Small Parts Inc, and anyplace that sells machinery parts
and supplies. I inherited a couple of large tubes, and these seem to be a
lifetime supply, so am not sure other than checking Dow Corning for a
distributor list, where to look for this stuff today.
New open type Ball Bearing races come with only a light protective oil, , and
they expect users to pack them with the appropriate viscous grease for your
application. It seems that automotive applications in years gone by relied
upon the regular service station visit to restore lubrication, and greases
were put into car bearings that broke down with temperature extremes and were
picked for economy as a main consideration. The synthetics available today
allow a better choice to be made than only petroleum derived grease. I have
found many cases of seemingly little or inappropriate lubrication design, and
long term survival of a chosen lubricant is apparently not an easy thing to
predict, especially in electronic applications. Not many EEs ever have a
course in what grease is supposed to do, and thus probably just pick whatever
is handy for mechanical drives; or if an ME is around, they might not want to
bother him for such a "small" matter.
It is like the situation with thermal design that is so lacking in many modern
electronic/ computer boxes. Someone sticks any cheap fan on the box, if the
heat sink feels too warm, and it is left at that. But that is another pet
peeve, about how many inadequate fans I have to replace each year! (Want long
quiet life from your computer and drives? Replace factory sleeve bearing fans
with ball bearing fans.) Sleeve bearing fans last only one to two years in
pretty heavy use we see.
73, Stuart K5KVH
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