Subject:
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Re: Grade Crossing Signal Thingy...
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Newsgroups:
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lugnet.trains
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Date:
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Sun, 19 Dec 2004 07:59:29 GMT
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Viewed:
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1434 times
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In lugnet.trains, Joe Strout wrote:
> In lugnet.trains, Ross Crawford wrote:
>
> > Easiest way is to have a stop of some kind at both extremeties of movement, and
> > introduce some kind of slip into the drive mechanism, like rubber bands or a
> > slip clutch http://www.peeron.com/inv/parts/60c01
> >
> > Then each cycle runs the motor longer than it needs, and the clutch slips when
> > the bar reaches the stop.
>
> How safe is it to routinely torque that slip clutch? I usually put it in for
> safety, but try not to need it -- something like a rope ladder for the upstairs
> bedroom.
>
> I'm thinking of a situation where a four-year old (and possibly several of his
> friends) might be leaning on the power button -- or even, click it into the "on"
> position and not quickly realize how to shut it off. Will the slip clutch keep
> the motor safe even if this happens frequently? Or, will it heat up/wear
> out/otherwise repay my abuse?
I don't know, I've never tested it under such duress. I don't imagine it would
damage the motor at all, but it may damage the clutch after prolonged use.
> I've worked out a mechanical limit-stop mechanism that I feel confident in, but
> it's bulky. If my fear of relying on the slip clutch is nothing but
> superstition, then I could make my module quite a bit smaller.
I've found the easiest way is with rubber bands, and though it is usually a
little more bulky, it can still be made quite small. With such a small load, a
single bush on each shaft should work fine, or you can use a wedge belt wheel if
you want a speed reduction. Rubber bands are much cheaper than slip clutches ;)
ROSCO
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Message is in Reply To:
 | | Re: Grade Crossing Signal Thingy...
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| (...) How safe is it to routinely torque that slip clutch? I usually put it in for safety, but try not to need it -- something like a rope ladder for the upstairs bedroom. I'm thinking of a situation where a four-year old (and possibly several of (...) (20 years ago, 18-Dec-04, to lugnet.trains)
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