Re: Need speed switch for DIY funicular/hillside elevator

[Frank Olson <Use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx>]

astutesolutions@xxxxxxxxxxxxx wrote:
>>I like Doug's idea of the automatic brake.  I also think you should put
>>solid sides on it to keep people from "dangling their legs" through the
>>railing like I observed in one of the movies.  I also think you should
>>employ some sort of gate, permanently mount the controller and
>>incorporate a safety switch that would prevent the device from moving
>>with the gate open.
>
>
> Yes, all good points.
>
> Solid sides, yes.  The vid was from the weekend we first got it done.
> I plan on finishing it with side pickets such as a deck.  I also need
> to put the rail back up on the deck with a gate so we can keep small
> kiddies or dogs from falling off.  I can put a limit switch to prevent
> it from running when open on the main deck, but don't really have a
> good solution for that on the cart since it is wireless.  I think it
> will eventually be more of an education thing.  The legs dangling
> although not prefered was actually not too worrisome at that point
> since the front of the cart is 4 feet off the ground.  But eventually
> the sides would prevent that.
>
> As to the slack, I was originally thinking of something like that, but
> with the cable being so heavy, there is actually much slack midway down
> in the cable when it is descending, and there will be even more once I
> increase the speed of it (variable speed controller).  That would work
> well in the event of the cable snapped, but that is pretty unlikely
> having 2 wires snap at the same time.
>
> In the event of a free spool, there are 2 places I could slow it down.
> Either up top at the spool with some kind of cable grapple, or on the
> cart assuming a I had a fixed cable running from top to bottom that the
> cart straddled and ran through some eyebolt/pulley scenario.
>
> The trick is, how to determine when it is going fast.  I almost need
> some kind of centrigal device on the cart or at the spool  that cuts a
> cord or triggers something when it gets going too fast.  I don't have
> to worry about a a false alarm start surge because the motor controller
> ramps up the speed when starting.
>
> Thanks!
>


What you really need is a "third rail".  You could then install a set of
brake calipers on the cart to act as an emergency stop.