Subject:
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Re: A LEGO double-throw switch?
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 22 Aug 2005 21:19:16 GMT
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Viewed:
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991 times
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In lugnet.robotics, Kevin L. Clague wrote:
> In lugnet.robotics, Brian Davis wrote:
> > So I've got an application where a forklift loads a crate onto a conveyor
> > belt. I could then start the conveyor belt up by having the forklift throw a
> > polarity switch. What I would *like* is that when the crate gets to the other
> > end, it somehow stops the conveyor motor again, (here's the tricky part),
> > leaving the system in a state where the next forklift delivery can re-trigger
> > the whole system from the "front end", as it were.
> > Oh, did I mention I wanted to do this with just polarity switches, no RCX or
> > other "intelligent" systems in the loop?
> > The picture I've got in my mind is something like a light with two wall
> > switches - change the state of either switch, it changes the state of the light.
> > I'm thinking I can do it with a looong string from the terminal end back to a
> > polarity switch at the head of the line, but it seems... clunky. Is there any
> > electrical solution? Can I reproduce my household wiring in LEGO (I promise I'll
> > keep the voltage... a *little* lower)?
>
> Hi Brian,
> How will the package arriving at the other end "throw a switch?". Is there
> enough friction between the package and the belt? Will there be a mechanism in
> the belt itself to "go halfway and stop"?
>
> If you only used one polarity switch, and had both ends control it, I could
> see how this might be done. The forklift rotates the switch on, by turning the
> switch a quarter turn. When the package goes to the other end, a special link
> in the conveyor belt rotates the switch the opposite direction from the forklift
> to turn itself off.
>
> The conveyor would have two special links that turn the conveyor off. The
> package would just go for the ride, playing no role in actually switching the
> conveyor off.
>
> 1. The initial conditions make sure the conveyor belt is such that it appears
> to just have turned the conveyor motor off.
>
> 2. The forklift drops the package on the belt, and turns the motor on.
>
> 3. The conveyor goes until it turns itself off. The package happens to be at
> the other end.
>
> Does this make sense?
No, I think you should use one polarity switch, without handle to greatly reduce
the friction needed to throw it. Putting the crate on the conveyor throws the
switch, and when the crate gets to the other end it could push a lever, or
better still use it's weight, to physically move a linkage that switches the
original switch off. Like an old-fashioned railway signal box.
The linkage could be made of long technic axles.
Steve
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Message has 1 Reply:
 | | Re: A LEGO double-throw switch?
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| (...) I agree the simplest solution is to use a single switch with one linkage operated by the forklift to switch it on, and another linkage operated by the falling crate, that switches it back off, ready for the forklift. ROSCO (19 years ago, 22-Aug-05, to lugnet.robotics)
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Message is in Reply To:
| | Re: A LEGO double-throw switch?
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| (...) Hi Brian, How will the package arriving at the other end "throw a switch?". Is there enough friction between the package and the belt? Will there be a mechanism in the belt itself to "go halfway and stop"? If you only used one polarity switch, (...) (19 years ago, 22-Aug-05, to lugnet.robotics)
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