Note the cell phone and car keys next to the ring gear for scale.
This is a pseudo herring bone gear to eliminate all external
gear thrust loads. The angles are chosen to pump the
oil out of the gear to reduce "oil churning".

Paul Lamar

Bill Freeman wrote:

Why "pseudo herringbone"?  Looks like a herringbone gear
to me.  After analyzing the planet carrier for a three planet
gearbox a few years back, I am impressed with the design of
the carrier, looks hell for stout.  What is the RPM?  This is
not just a huge amount larger (about 2-3X in external dimensions)
than a 100 HP gearbox that GE provided with a 3X overdesign
due to impeller surging in the particular application.  I assume
this is pretty high RPM to keep the torque down so the box
can be this small.

Bill

It is the gap between the two angles. That means the gear is easier to cut
than the traditional herringbone gear set.

Assuming for the moment the fan is 112 inches in diameter and the tips
are going 1.3 mach at sea level...what output RPM is that? From scaling
the gears one can make a determination of the ratios possible and that
should give possible input RPM's. Reverse engineering :-)

BTW it was extensively tested at 40,000 HP and the efficiency was above
99%. So don't let anybody say planetaria's are inherently inefficient.

Paul Lamar
 
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