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Homeowner Forum / Home Automation / October 2006Brake method needed for hillside lift
(this is a repost from comp.home.automation). Thanks. My dad and I built a homemade hill lift (in Europe refered to as funiculars) in Eastern Tennessee. You can see a working demonstration and picture of it at: http://www.funimag.com/photoblog/index.php/20061026/a-do-it-yourself-... The tram works fine, but I am trying to figure out some kind of simple safety mechanism in the event that the spools break loose from the gearbox or shaft and start rotating freely. Since my wife and kids ride this thing, I'd like some kind of backup solution in the event of major catastrophe. We are using 2 cables instead of one even though one can handle 5 times the max load, and we have a braking motor to stop, but both of those would be moot if the spool spins out of control. I am thinking of having some way of measuring the outfeed speed of the cable (or spool) and have some emergency brake apply if a limit is exceeded. Any suggestions? I thought about putting fan blades at end shaft of the spool to have air slow it down, but that would be a little unsightly. I'm looking for a simple solution, one preferably without a computer since this is outdoors and needs to be functional 100% of the time. Thanks in advance. Jeff The simplest way would be to wrap and connect the cable to (a spring loaded?) spool under the carriage that would allow a lever to drop down on some type of stops affixed to the tracks so that if the cable ever became slack it would drop down and engage on one of the stops. I remember this method being used on larger garage doors as a safety in case the counterbalance failed. Let me know if this makes no sense verbally and I'll sketch it out for you.... > (this is a repost from comp.home.automation). Thanks. > [quoted text clipped - 26 lines] > Thanks in advance. > Jeff > The simplest way would be to wrap and connect the cable to (a spring > loaded?) spool under the carriage that would allow a lever to drop down on [quoted text clipped - 4 lines] > Let me know if this makes no sense verbally and I'll sketch it out for > you.... Yes, this makes sense but the only problem is detecting the slack. Since the angle is 30 degrees and travels about 150 feet, the cable naturally has slack when going down. It rests on the support a bit as the cart pulls it down. Also, in a freespool event where the cable drums are moving freely, there wouldn't be enough slack to react on. One one of the other boards (comp.home.automation) a suggestion was made to hook up the drums to an air compressor (without the electric motor) such that it would have resistance at higher speeds. Thanks for the suggestion! This might be a bit complicated, but a centrifugal brake should do the job. Ideally, the brake engages if the drum starts spinning. As the brake slows the drum, it eases up a bit, allowing a safe descent. ISTR they use something like this on the tram at a ski lodge in NH. Thinking it up was easy. Engineering it is outside my skill set. :^)  SignatureRegards, Robert L Bass =============================> Bass Home Electronics 941-866-1100 4883 Fallcrest Circle Sarasota · Florida · 34233 http://www.bassburglaralarms.com =============================> >> The simplest way would be to wrap and connect the cable to (a spring >> loaded?) spool under the carriage that would allow a lever to drop down on [quoted text clipped - 16 lines] > > Thanks for the suggestion! > This might be a bit complicated, but a centrifugal brake should do the job. Ideally, the brake engages if the drum starts spinning. > As the brake slows the drum, it eases up a bit, allowing a safe descent. ISTR they use something like this on the tram at a ski > lodge in NH. > > Thinking it up was easy. Engineering it is outside my skill set. :^) Yes, a centrifugal brake or something similar to it is what we need. Finding an easy way to do it is what I'm struggling with. Thanks! How about a clutch off of a go-cart or such. A gear on the cable spools and a short chain to the gear that is already on the go-cart clutch assembly. The normally "driven" portion of the clutch would be mounted stationary. >> This might be a bit complicated, but a centrifugal brake should do the >> job. Ideally, the brake engages if the drum starts spinning. [quoted text clipped - 6 lines] > Yes, a centrifugal brake or something similar to it is what we need. > Finding an easy way to do it is what I'm struggling with. Thanks! I'll check some oline sites for those. That would be heavier duty than a bicycle setup. Thanks! > How about a clutch off of a go-cart or such. A gear on the cable spools and > a short chain to the gear that is already on the go-cart clutch assembly. [quoted text clipped - 10 lines] > > Yes, a centrifugal brake or something similar to it is what we need. > > Finding an easy way to do it is what I'm struggling with. Thanks! Gemini, that may be the best answer. It appears to be like a centrifugal brake almost. I could get a go-cart transmission setup with the brake partially engaged. When the speed gets up to the clutch engage speed it would have brakes applied, assuming the brake pad didn't slow it down enough for the clutch to disengage causing a drop-grab-drop-grab effect. > How about a clutch off of a go-cart or such. A gear on the cable spools and > a short chain to the gear that is already on the go-cart clutch assembly. [quoted text clipped - 10 lines] > > Yes, a centrifugal brake or something similar to it is what we need. > > Finding an easy way to do it is what I'm struggling with. Thanks! |
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