Subject:
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Re: 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 21:41:19 GMT
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Original-From:
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alex wetmore <alex@&spamless&phred.org>
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Viewed:
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991 times
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On Wed, 27 Jan 1999, Cyberia wrote:
> 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.
Note that my fathers design (the 2nd one on the page) also allows you to
get rid of having the offset gear on a 2nd level, but you would have to
use two 16t gears and a 8t pinion. We were trying to reduce the usage
of the pinion gears because they seem to be very inefficient compared to
other lego gears.
One thing that I really like about your layout is that you don't use
any of the fairly rare 1x1 pieces with a hole in them (wonder what the
technical term is for this piece). Building a strong design around these
can be tricky.
I really enjoy this list and getting to see how many people have
tackled the adder/subtractor design. It really makes it possible
to get technically interesting designs done quickly, by having mass
brainstorming at this level.
> 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.
This is also how the design that my father did drives the differentials.
Your first layout on your page is a bit more compact, but very similar.
I have a robot based on my dad's design that I need to take a part and
do a better job of photographing so that people can really see how its
put together.
Glad to see your pictures, and I plan on adding a link to your site from
mine when I get a chance.
alex
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message is in Reply To:
 | | Variations on the "ADDER SUBTRACTOR" ("differtrans" ?)
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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 (...) (26 years ago, 27-Jan-99, to lugnet.robotics)
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