Ed wrote:

Well, I measured the oil flow I get through the Ross Gearbox today with the
engine producing 80 psi oil pressure.  At 80 psi, I get 16 oz/1 pint per
minute or 7.5 gallons/hr oil flow out of the drain.  Its a steady stream, so
easy to see how it would blow oil past the seal if the Ross unit is not
adequately drained.

I located a fuel pump that looks idential to the one that Charles Halbert
uses as a scavenger pump that I may install.  However, in researching
seals/oil seals/radial seals, I have found a class that looks very
interesting.  They are apparently designed to seal against a rotating shaft
for fluids up to several hundred psi.  The appear to be an order of
magnitude improvement over the oil seals that are in the Ross unit.  If
indeed my initial impression is correct, it may provide an answer.  See
attachment for a couple of  classes of such oil seals.

charles.harbert

Ed,I went to their site-very interesting. At times my unit will weep a few drops
of oil when cold due to the heavier viscosity. It would be nice to have a seal
that would stop it altogether. Also, if the scavenge pump were to fail, this
would prevent possible blowout of the seal. I suspect that the highest pressure
possible is less than 5 psi because of the always open drain line. If you find
out that they make an applicable seal to fit the Ross, pls let me know. Thx.

The flow rate you mentioned sounds like the numbers I used (but my memory is
poor). The fuel pump (scavenge) is rated at 12 gph as I recall which allowed me
to increase the flow to the unit for cooling and lubrication. You really don't
want the gbox full of oil because it adds (pumping) heat and uses hp. It was
designed to only have about a half inch of oil in the unit.

p.s. kinda amazing how much oil can pass thru a .030" orifice, isn't it?

 
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