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Subject: 
RE: gear differential
Newsgroups: 
lugnet.robotics
Date: 
Thu, 19 Nov 1998 19:56:13 GMT
Original-From: 
Tim McSweeney <tim@ams.*ihatespam*co.nz>
Viewed: 
2033 times
  
Yeah I had thought of that but the problem is you need one motor to do the
driving and one motor to do the switching, The way the gearbox is presented
in the model only This only gets you two outputs,, so you haven't gained
anything, in fact you've lost compared to just using the motors because you
can't drive them both at the same time.  If you add a second motor to do
more complex switching (I really need a scan of the model to show you (help
anyone?)) you get FOUR outputs from three motors. But you can still only
drive one at a time. This is OK for some models, but not far anything like a
mobile Tank that needs both tracks running at the same time.

Of course the solution is to design a better gearbox than the one from Lego,
but that can get tricky :)

On a side note, a Differential can be used to produce two ONE-WAY outputs
from a single motor just put opposing ratchets on either side of the
differential.  Turn the motor one way and the left ratchet locks up turn it
the other and the right ratchet locks up.


Cheers
Tim





I could be wrong, because I can't open my Mindstorms yet(b-day not til
12/11) but it seems logical that you could use the gear
differential, or a
jury rig of one, to drive however many distinct items as
there are gears by
redirecting the output.

Just a thought, but it could increase the number of effective
motors by a
multiplier of the number of gears.

trowt
-----Original Message-----
From: Tim McSweeney <tim@ams.co.nz>
To: lego-robotics@crynwr.com <lego-robotics@crynwr.com>
Date: Thursday, November 19, 1998 1:41 PM
Subject: RE: gear differential


Actually I'm still proud of it - I built an all-LEGO automatic
transmission.

Only *how* it worked was by using pairs of the little • crown bushings
(seemingly defunct as of this year?) as clutches, a pair at • each end of
an axle (adjusted very *very* carefully to get exactly • zero clearance
when turning free) with a worm gear thrusting against a • rubber band to
measure the applied force (and of course the usual 2:2 and 3:1 gear
ratios around the two ends)....
Its easier to build transmissions using the freewheels 16t

<snip>

Those freewheeling gears are really cool. I just bought the
Technic Shuttle
and it comes with a whole lot of them It uses them in quite a complex
gearbox to drive all of the operations of a single motor. If you take
another look at the gears you'll notice the are sort of
hollow, but on the
inside there are little ridges that stick out.  The Gearbox
includes another
piece that slides on a shaft and locks into these.  really
neat and compact,
makes wonderful clutch.   I suspect It was first used in the
gearbox of the
super car.

All I have to do now is work out a use for them with mind storms.

Cheers
Tim





Message has 1 Reply:
  RE: gear differential
 
(...) check out (URL) for a nice device for controlling a tracked vehicle. I've modified it slightly to flatten it a layer and use a micromotor for the steering and a one of the motors from the Mindstorms set (a mini motor) for the power. Two mini (...) (26 years ago, 19-Nov-98, to lugnet.robotics)

Message is in Reply To:
  Fw: gear differential
 
I could be wrong, because I can't open my Mindstorms yet(b-day not til 12/11) but it seems logical that you could use the gear differential, or a jury rig of one, to drive however many distinct items as there are gears by redirecting the output. (...) (26 years ago, 19-Nov-98, to lugnet.robotics)

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