[R-390] Planetary Gear Assembly

[John KA1XC]

Interesting technique. You know, the springs in those planetary gears are so
weak I'm never sure when to actually start counting the gear teeth when
loading them. I've never used hemostats for holding any of the other split
gears together, a small screwdriver blade always worked fine for me. Maybe
I'll try it next time.

For holding the planetary gears I've always used plain old solder; wrap a
couple of inches or so of  it around the tensioned gear front to back so as
to engage the teeth and then finger twist it tight. Because the solder is
soft it mushes into and around the gear teeth nice and close. Then after the
whole thing is assembled just snip the solder loose. Some folks use solid
hookup wire too.

John


----- Original Message ----- 
From: "Barry" <N4BUQ at aol.com>
To: <r-390 at mailman.qth.net>
Sent: Sunday, March 06, 2005 9:39 PM
Subject: [R-390] Planetary Gear Assembly


> Just thought I'd pass along a tip.  When I tried to reassamble the three
> planetary gears to their mating gears, I could never get them to go
together
> without something going wrong.  Preloading the anti-backlish gears and
> holding them with hemostats just wouldn't work.  The assembly would bind
and
> be misaligned.  I never did figure out what caused this, but I did figure
> out a way to successfully reassamble them.
>
> The method I used was to assemble the planetary gears without the clip
that
> holds the anti-backlash gear in place.  The assembly will go together
quite
> easily this way and there is room for the anti-backlash gears to move out
of
> the way slightly so that they don't interfere in this first step.  Of
> course, you pre-load the anti-backlash gear in the center at this point as
> it can't be done later.
>
> After tightening the three screws that hold the planetary gear shafts, you
> can then load each anti-backlash gear, one at a time.  There is sufficient
> clearance just above the center gear to allow this.  It's a bit tricky to
> get both nibs of the internal spring into their respective holes in each
> half of the gear, but it can be done.  With the anti-backlash gear cocked
> just a bit to clear the mating gear, you can put a few teeth of spring
load
> on the anti-backlash gear half and then let it slide down onto the mating
> gear.  Press the "C" clip in place and proceed to the next gear.  It
really
> worked out rather easily.
>
> AND, if you want some real fun, take a toothbrush and some Brasso(tm) to
> that big brass gear assembly that is comprised of two larger gears that
are
> riveted together.  Wow.  Does that thing ever shine up nicely!  Yeah, I
know
> it won't work any better shiny than dull, but there's just something about
a
> sparkly gear that satisfies my R390A rebuilding soul.
>
> Happy rebuilding,
>
> Barry(III) - N4BUQ
>
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