Re: Need speed switch for DIY funicular/hillside elevator

[astutesolutions@xxxxxxxxxxxxx]

Robert L Bass wrote:
>
> Actually, I was thinking that you could use one or both of the main cables to operate the brake.  The third cable idea was from
> another gentleman.  Given what you've said about the weight, slope and cable strength, I seriously doubt you'll have a broken cable
> issue.  If you use the operating cables to keep the brake pulley / lever taught, the weight of the tram will keep anyone from
> jostling the cable off the pulley.  You can use a catcher (U-shaped cover) above the pulley so that the cable is trapped at the top
> if this is still a concern.
>
> The main reason I like this idea (really from Doug's suggestion) is it's simple.  It require no electronics and no electrical power
> to operate.  Also, you could easily build in an over-ride to allow the tram to descend in the event of an erroneous safety system
> deployment or a single cable failure.  A manual lever could be operated to allow you to walk the tram down the hill.
>

Robert, what you said about Doug's idea makes complete sense.  I was
initially thinking of something like this pre-construction, but the
cable rigidity discouraged the concept.  But That was when I was
thinking of assuming there would be total loss of tension and gravity
would "flip the switch" so to speak.

To describe the way the cable is mounted, imagine the floor lifted off
as you are on the cart facing down hill.  You would see a cable under
your left foot going to the down hill corner, to a pulley, then over to
the side pulley on the right and then back under your right foot.  So
in a sense, the cable makes a large "U" (upside down that is).  If I
were to add a center pulley such that it made a "W" attached to a
spring, I could as you and Doug say, use springs and the cart's weight
to adjust to the condition of freespool or just normal use such that a
small loss in tension could grab onto the cable.

Another benefit to it is that I could use this method to hold the cart
in place as I work on it, although I would probably count on a little
more than just the grapple.

The trick will be to come up with a method to grab the wire.  I've
thought of an eyebolt with a spring (like a valve spring) to grab it in
sheer, or perhaps a rod with two pins that torques and binds the cable.
 I think the best would be a go kart brake.  They are mechanical (non
hydraulic) and have a lever built in.  I would probably need to wear a
groove in the pads to increase the surface area.