tag:blogger.com,1999:blog-4063450658421522356.post3591446459805509198..comments2024-03-09T04:13:55.185-06:00Comments on Open PRT specification project: 131> Climbing a ChainDanhttp://www.blogger.com/profile/16303568401426087509noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-4063450658421522356.post-79148242785052860042021-07-10T05:01:19.838-05:002021-07-10T05:01:19.838-05:00Very nice. I was thinking about a rack-and-pinion...Very nice. I was thinking about a rack-and-pinion system myself since I don't see anyway elevated PRT will work without ground level stations. <br /><br />The only other possibility was an LIM brake on the descent and LIM assist on the ascent.<br /><br />There are three other suspended PRT designs which have vehicles descending down off the main guideway: SkyTran, Metrino, VubaPRT. The first two have segments of test track and the third say they are on the verge of building one but I've never seen any practical demonstrations.<br /><br />Here's a video about Vuba as they are the latest to produce anything. (It's always easy in CGI!) https://www.youtube.com/watch?v=630YdXigPws<br /><br />FWIW this blog recently got a post in the PRT Facebook page: https://www.facebook.com/groups/Personal.Rapid.Transit/permalink/3926553580799723/tjejojyjnoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-12834426664952263692014-04-18T08:33:16.839-05:002014-04-18T08:33:16.839-05:00Great post! The fact that you means someone is rea...Great post! The fact that you means someone is reading and liking it! Congrats!That’s great advice.<br /><br /><a href="http://www.supercuttingtools.com/chain.php" rel="nofollow">Chain Sprocket Hobs</a>Anonymoushttps://www.blogger.com/profile/09657749608886896559noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-48890564345523881632014-04-18T08:23:44.944-05:002014-04-18T08:23:44.944-05:00What to say i praise of this blog, which contains ...What to say i praise of this blog, which contains a lot of amazing information as well as the thoughtful writes.<br /><br /><a href="http://www.supercuttingtools.com/chain.php" rel="nofollow">Chain Sprocket Hobs</a><br />Anonymoushttps://www.blogger.com/profile/09657749608886896559noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-15968721440536237912013-01-22T04:55:10.217-06:002013-01-22T04:55:10.217-06:00Great Work and nice sharing really. Thanks for thi...Great Work and nice sharing really. Thanks for this and keep posting ike this useful information. It is really helpful for me. <br /><br /><a href="http://www.gearcuttingtool.com/products/Gear+Hobs/16" rel="nofollow">Gear Hobs</a>Anonymoushttps://www.blogger.com/profile/02988158096861590713noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-4010489480384444742011-11-15T23:19:16.439-06:002011-11-15T23:19:16.439-06:00Andrew, you are certainly right about the need for...Andrew, you are certainly right about the need for a braking mechanism. My working assumption is that each vehicle would have a truck-style brake where it automatically engages if there is no power. I am still working out the details. Power, though, would still come from the battery in an outage, and there should be plenty. Also, do not assume that the motors would be free turning without power. Low RPM, permanent magnet motors generally exhibit extremely strong “cogging” between the magnets and the steel in the coils, and circuits can be added that mean that any rotation feeds the electromagnets to further freeze the motor. This might not brake a falling bogey completely, but my guess is that it would slow it a whole lot. <br /><br />As for speed of ascent, let me point out that I am designing sort of a super-PRT vehicle to see what designs won’t limit future capabilities. I really doubt a system would ever start out with the full functionality and power I have described and therefore I would want the system to work decently with a lower power vehicle. I guess I would start at something like a fast walking speed.(but going straight up) I wouldn’t be trying to climb buildings, at least not very high. I just can’t see needing a PRT vehicle on the upper floors anytime soon. At least I wouldn’t design a vehicle for it. Really fast and powerful climbing capability would be best accomplished with a special track or a PRT elevator with counter weights, I would think. I’m thinking pretty tame stuff here. Keep in mind that with a dry track and rubber wheels, the inclines can be fairly steep even without the chains, so ascent probably would be a bit faster that way. I don’t think 20 seconds or so to get up to the treetops is prohibitively slow, do you? <br /><br />BTW the test strength I gave for the sprockets is very conservative. If the sprocket teeth are about pinky-finger sized, and they are hardened alloy steel, the working load limit should be over 10,000 lbs. each. A sprocket wouldn’t slip on a single snapped tooth anyway, since there are always a couple of others that are semi-engaged.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-8227922999944899852011-11-15T23:02:47.279-06:002011-11-15T23:02:47.279-06:00Dan the Blogger responds - in typical, long-winde...Dan the Blogger responds - in typical, long-winded fashion... <br /><br />I see little benefit to putting machinery into the track at this point. (Although I was thinking about it way back in post 16) Adding four sprockets, four bearings and four rings to each vehicle is next to nothing – probably cheaper than adding a coupler. Not that it wouldn’t be a simple matter mechanically, and I would not want to “design in” something that would preclude it. It’s just that the need for such a system strikes me as being application-specific, and I’m sort of adding a bare-bones generic capability at this point. I am especially interested in keeping station costs down, which weighs against that option. Of course “not designing something out” actually means that you have to “design it in” just to check if you’re designing it out!<br /><br />As far as fencing goes, that is something I need to figure out. Obviously sensors are just getting better and better, and many are so cheap that there could be a lot of redundancy… camera range finders, infrared and broken beam sensors are examples. There is also this emergence of QR codes. Paint one of those on the landing spot, and if there is a code error, switch to plan B, whatever that is. One idea uses the security cameras. Could an anomaly trigger a real-time visual for some guy looking at screens in a control room? Does “plan B” need human judgment? (If there are multiple, alternative docking bays, maybe not, unless there are multiple aborted dockings) Also the tilt sensors (for self-leveling the cabin) would pick up physical contact before anyone would get squashed. And there are warning sounds… I have even thought of landing on a collapsible platform or simply using weight sensors on the landing platform to detect obstacles. I am most worried about pranksters and false positives…and the “Plan B.”<br /><br />As far as the bogie getting squeezed, it is true that the inner dimensions of the track need to change for curves – especially tight ones. This is true for both side and vertical turns. The track ribs will have slight variations and the steel fabricators will need to use some jigs and spacers to make sure they don’t goof up. Part of why I have eliminated angle iron in favor of round stock has to do with the fabrication procedures resulting from this issue.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-18465906131646090592011-11-14T15:22:57.439-06:002011-11-14T15:22:57.439-06:00So Dan, I take it that you're saying that havi...So Dan, I take it that you're saying that having two chains with two wheels each is enough redundancy in the event that there is a defect or failure in one of the sprockets or chains. I suspect that you might need some additional independent system to brake the vehicle in the event of failure. What happens, for instance, if the vehicle loses power? The motors would just spin and the vehicle would more or less freefall, no? So, maybe you would need to add some kind of ratchet mechanism as well. Or would the emergency brakes that clamp the track be sufficient to arrest the vehicle and support its weight?<br /><br />What kind of speeds are you envisioning for vertical ascent/descent? Honestly, the vehicle could well be capable of higher speeds than most users would adopt--most elevators don't have windows for a reason. You might be able to address this by frosting the windows (this technology is used on the 787 Dreamliner rather than shades). I think in the past you envisaged having guideways climb buildings on the exterior of the structure in order to reach stations on, say the 100th floor. I can see some users getting a bit nervous if the vehicle is more than 40 or 50 feet above the ground.Andrew Fhttps://www.blogger.com/profile/09182432042622426328noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-54698877667052995472011-11-14T05:20:40.059-06:002011-11-14T05:20:40.059-06:00I agree that ability to build cheap tracks and che...I agree that ability to build cheap tracks and cheap stations in all possible evironments is a key requirement. Otherwise we would unnecessarily limit the scope of use of the PRT system. (Private homes, forest roads, already built areas etc. to be covered.)<br /><br />One alternative to this design is to build the "elevator" mechanism as part of the track (instead of part of the bogie). One could connect the bogie to a local moving element (bogie style or something simpler) that woud first connect to the bogie and then lead it up or down the steep section. That would keep the bogie simpler an could allow different implementations of the actual "elevator" mechanism. Only the connectig element would be standardized (like between railway cars, or simpler).<br /><br />(In the picture the bend from the level section to the steep section seems to be too tight fro the bogie.)<br /><br />You may need some fence around the "landing area" if the system is fully automated. Or maybe there is just an emergency brake for the passengers if the track is not clear.Juho Laatuhttps://www.blogger.com/profile/15072614531174046945noreply@blogger.com