Re: Need speed switch for DIY funicular/hillside elevator

[astutesolutions@xxxxxxxxxxxxx]

astutesolutions@xxxxxxxxxxxxx wrote:
> So here's what I'm thinking.  On the end of the spool, have a large
> sprocket that drives a chain to a smaller sprocket.  The smaller
> sprocket is hooked up to a go cart transmission (centrifugal clutch)
> that is underneath the drum units.  The gearing would mulitply the
> spin.  At high speed rotation, the clutch engages and the wheel turns
> and yanks the mousetrap and pulls out a jumper that opens the emergency
> stop button (motor shutoff).  Then it would take a manual reset to
> unlock, but if its spinning freely something major is wrong such as a
> broken coupling or a broken shaft inside the gearbox.
>

Researching this I'm not sure it would work.  Most of those clutches
activate at around 3500 RPM, and by my calculations the drums are
moving at 23 rpm (2 minute trip for 142 feet on a 12 inch drum) and
perhaps as fast as 30-50 RPM when I increase the VFD motor speed.  The
largest gear I can find has 112 teeth, and the clutch has 10 (drum
clutch ration of 11.2)  That would give me a max "regular" RPM of 560
RPM on the clutch.  By the time the thing got up to full speed it would
be going too fast.

Additional gears could be added to multiply this, but I'm wondering if
it would put too much torque on the gear to increase the drum/clutch
ratio to 60, but I don't know gears that well.