To LUGNET HomepageTo LUGNET News HomepageTo LUGNET Guide Homepage
 Help on Searching
 
Post new message to lugnet.roboticsOpen lugnet.robotics in your NNTP NewsreaderTo LUGNET News Traffic PageSign In (Members)
 Robotics / 3278
3277  |  3279
Subject: 
Re: Variations on the "ADDER SUBTRACTOR" ("differtrans" ?)
Newsgroups: 
lugnet.robotics
Date: 
Wed, 27 Jan 1999 21:41:19 GMT
Original-From: 
alex wetmore <ALEX@PHRED.ORGnospam>
Viewed: 
2812 times
  
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



Message is in Reply To:
  Variations on the "ADDER SUBTRACTOR" ("differtrans" ?)
 
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 (...) (28 years ago, 27-Jan-99, to lugnet.robotics)

16 Messages in This Thread:







Entire Thread on One Page:
Nested:  All | Brief | Compact | Dots
Linear:  All | Brief | Compact
    

©2005 LUGNET. All rights reserved. - hosted by steinbruch.info GbR