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Subject: 
Re: I wish Lego made an "Anti-Backlash Gear"
Newsgroups: 
lugnet.robotics, lugnet.technic
Date: 
Thu, 5 Apr 2001 05:16:40 GMT
Viewed: 
3740 times
  
Interesting , but  we need one for Lego! I do see what you are saying, and
It is an interesting solution,, although a little hard to visualize...Thanks!


In lugnet.robotics, Thomas D. Fulk, Jr. writes:


Tech question for us: Any body know what an Anti-Backlash gear
is? If Lego made one, we would all have super precise Robots and
mechanisisms! BERG carries them... Anybody know what I'm talking
about?



I know of 1 type of zero-lash/anti backlash geartrain.


It's hard to put it in words but I'll try.  My example assumes there
are only 2 shafts but it can be applied to as  many shafts as you
need.


In my example S1 represents  our first shaft.  Drive or driven, you
choose.  result is the same.  S2 represents the other shaft in our
gear train.  G1and G2 are 2 separate gears on S1, and  they are both
in mesh with G3 which is located on S2.  G2 is not splined to S1 like
G1 is, and is only there to act with the spring to remove the lash.

    Now.... Our first gear is actually  2 thin gears (G1 and G2)
together on the same shaft (S1), working as 1 gear... mating to a
single thicker gear (G3) with a torsional spring force causing G1 and
G2 to rotate in opposing directions, except the teeth of G3 stop them
from rotating more than the lash between the G1/G2 pair and G3.
Really the G1/G2 pair is acting a variable pitch gear that perfectly
mates to G3 at all times.

  If the force required to move the load is more than the spring
force between G1 and G2  there can be lash in this setup.  In the
real-world application where I have seen this used (Toyota 3.4 V6
engine, to mate the two camshafts located in each cylinder head) there
is a way to lock G1 and G2 together before you separate them from G3.
I assume this is because the spring is so strong that it would be hard
to rewind in the field.

Thomas















Message has 1 Reply:
  Re: I wish Lego made an "Anti-Backlash Gear"
 
(...) I was going to say this solution is easy, but then I tried it. There are only two shaft's in this example. As lego don't make don't make a 'double width gear' You'd have to use four to make it in lego. All you'd need is three normal 16 tooth (...) (24 years ago, 5-Apr-01, to lugnet.robotics, lugnet.technic)

Message is in Reply To:
  Re: I wish Lego made an "Anti-Backlash Gear"
 
(...) I know of 1 type of zero-lash/anti backlash geartrain. It's hard to put it in words but I'll try. My example assumes there are only 2 shafts but it can be applied to as many shafts as you need. In my example S1 represents our first shaft. (...) (24 years ago, 5-Apr-01, to lugnet.robotics, lugnet.technic)

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