Subject:
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Variations on the "ADDER SUBTRACTOR" ("differtrans" ?)
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 27 Jan 1999 21:31:46 GMT
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Viewed:
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1179 times
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Hi, fello legoroboticists.
My son Michael has a web page via Geocities, where we decided to begin to
assemble various lego oddities to share with other enthusiasts.
Much interest has centered around the "adder/subtractor" transmission, a
design that I first saw on Leo's lego page
http://carol.wins.uva.nl/~leo/lego/diff.html . Later, another two
variations appeared at Alex Wetmore's site http://www.phred.org/~alex/lego/
.
The common issue with two of these designs is the use of an "offset"
intermediate gear on one side to tie the two differential shafts together
out of phase. This gear is mounted at a different level from the common
centerline of the differentials. In this way, stress forces these gears
apart, concentrated where legos are the weakest (the interface between
bricks). Alex's design (the first one on his page) seems to have not only
overcome this, but has the diffs closer together. This is cool, but there is
a disadvantage. It is not possible to mount the motors directly over the
diffs at that close spacing.
The "tandem" design as we have termed it, is arranged such that the motors
can drive the differentials directly using proper gearing, and they can
mount above the diffs for a very compact drive system.
Anyway -
The variations found here http://www.geocities.com/SouthBeach/Surf/6112/ are
optimised to eliminate the offset-gear stress point. Two variations were
created, one which minimizes the distance beteen the differential mainshafts
(this I called the "adjacent" variant), and one that minimizes the width of
the overall transmission (this I called the "tandem" variant) and makes for
compact motor/transmission integration.
The original photos are quite large, so we reduced them various ways to help
minimize bandwidth for the casual observer. The "freakin' HUGE" versions are
also there, for the serious gearhead who wants to see just how dusty my lego
pieces have become over time. :-) :-)
I must say I had a lot of fun doing this, but I hate the term
"adder-subtractor" (no offense to Leo). We should coin a shorter term for
referral to this design and it's variations.
Differtrans ? Difftrans ? any other ideas ?
--
SeeYa !
------------
Jim
----------------------------------------------------------------------------
Hello... Is this thing on ?
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