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Subject: 
Re: motorized points - beating a dead horse
Newsgroups: 
lugnet.trains, lugnet.robotics
Date: 
Sun, 3 Dec 2000 05:33:06 GMT
Viewed: 
49 times
  
Great tip, I never thought about using multible pulley/rubber bands! A big
problem is the detent, the two at rest positions are very "sticky". Naybe
more then multible rubber bands can even move. I'll give it a try.
SteveB

In lugnet.trains, Juergen Stuber writes:
"sebarile-MOBL" <steve.e.barile@intel.com> writes:

Currently I am attempting to build an automated hump yard. The main problem
I'm tackling is the RCX controlled motorized points. I've spent 7 hours over
the last two days trying to build a motorized switch track that will run
forever with out ripping itself off the base plates and be very *forgiving*
at the edges of both states, turn or straight. What I mean by forgiving is
that the motor doesn't burn up or the gears do not get stripped off.

I like really simple and elegant solutions. For instance I would like to be
CPU switched with no feedback, again forgiving at the edges of both states
such that the motor can spin for 1.5 secs and not reap havoc. Hanging
elaborate clutch systems with differentials and angle sensors would not be
my first choice. Of course beggers can't be choosers.

I'm not exactly sure about your setup (I'm not into trains),
but how about a small pulley (half bushing) on the motor,
driving a medium pulley (with the six holes) on an axle on
whose other end is an 8t gear that drives a rack.
That setup works well for rack and pinion steering,
where you have similar problems.
If one pulley/rubber band is not enough you can put another one
in parallel (like in 8480), or you can experiment with the tension
of the rubber bands.

Jürgen



Message has 1 Reply:
  Re: motorized points - beating a dead horse
 
(...) I made a design that used a clutch gear and fit into a house. It worked very well when the switch was "warm" but wouldn't always trip it when it had been sitting for a bit. But it allowed the throw arm to fully though the switch one way or the (...) (24 years ago, 3-Dec-00, to lugnet.trains, lugnet.robotics)

Message is in Reply To:
  Re: motorized points - beating a dead horse
 
(...) I'm not exactly sure about your setup (I'm not into trains), but how about a small pulley (half bushing) on the motor, driving a medium pulley (with the six holes) on an axle on whose other end is an 8t gear that drives a rack. That setup (...) (24 years ago, 2-Dec-00, to lugnet.trains, lugnet.robotics)

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