Re: Need speed switch for DIY funicular/hillside elevator

[astutesolutions@xxxxxxxxxxxxx]

Dave Houston wrote:
> I think you should look at a motorized winch with a single cable to
> raise/lower the tram. I'm sure the manufacturers have seen similar
> applications and have addressed the safety aspects. In any event, it should
> be much easier to slow and stop the rotating drum of the winch than it will
> be to design and maintain any of the Goldbergian suggestions you've gotten
> here.
>
>      http://www.torkwinch.com/index-2.html
>
>
> http://davehouston.net
> http://tech.groups.yahoo.com/group/roZetta/
> roZetta-subscribe@xxxxxxxxxxxxxxx

The current set up is SOOO much better than a motorized winch.  I
haven't gone into much detail about it, but is being driven by a 5 HP 3
phase VFD (variable frequency drive).  It is driven by a $1,500 motor
controller that is programmable to vary the ramp up and ramp down
speeds as well as taking switch (wired and remote) inputs to trigger
events.  The whole setup was designed for over 5,000 lbs (with the
exception of the rails and cart) and should never have a failure event,
but I'm not so naive to assume it would never happen.

We are just trying to eliminate all possible forseen sources of
failure, and the most catastrophic I can think of besides the cart
falling over is a main shaft break causing a freespool.  The drums are
secured with 3 bearings on solid steel pillow blocks, so I don't think
if the shaft breaks the drums would fall off.  Of course another source
of failure would be a cable break, so we had 2 setup instead of just
one.

I don't think that all the suggestions are necessarily goldbergian.
There are 2 possibilities, stop it at the head unit (at drums) or stop
it at the cart.  Each offers its challenges, but not impossible.  Its
just a balance between what I can actually build, and what will take
the least amount of maintenance.