Paul Lamar wrote:

Actually the output shaft on the 2.85 rotates in the same direction
as the input shaft.

BTW I was looking for some illustrations on the WWW and I ran
across this blurb :)
************************************************
Helical planetary design -Helical gears have more
tooth contact and greater face width than spur gears.
This results in higher loads, smoother tooth
engagement, quieter operation and lower backlash.

I think there's a semantic error in that paragraph.  Greater tooth contact area should result in *lower*
loads for equivalent transmitted power, or (alternatively) the same loading across a greater tooth
contact area means a planetary can transmit a larger power for the same durability.

Special tooth profiles have been developed to further
optimize planetary gear performance. Since most
vibration occurs at the entry and exit points of a gear
tooth, revised profiles eliminates metal in these
areas, without sacrificing gear strength, producing a
quieter and stronger gear.

Well, to say that the tooth profile is "specially developed" for planetary gearsets is a bit
disingenuous.  The profile is specially developed for low entry/exit clatter (one of the primary sources
for gear noise). The same tooth profiles could be used on spur gearsets, but reduction in contact area
(that occurs regardless of the gearset involved) is much more deleterious for the spur gearset than the
planetary gearset.  This is primarily because the contact area in a typical planetary gearset is *way*
over designed when compared to the rated power capacity.  With the planetary gearset, the durability of
parts other than the gear faces is a bigger issue as compared to the spur gearset, where the contact
area effects (galling, spalling, etc.) are a big issue.

Where did you find that above quote?

Russell Kent

I don't recall. Some web site. Google "planetary gears."

Paul Lamar

The "higher loads" refers to the gears being able to carry higher loads.
Royce

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