I have only seen inclined screws. This is far from my area of engineering expertise, but my travels and work as a civil engineer has brought me close to more than a few of these machines. When stopped, it doesn't take long for all liquid to drain down to the bottom pool elevation. The clearances I was talking of were compared to a turbine aircraft engine, where the blade clearances are in thousands of an inch. The tube does not become near total full of liquid, but maybe 1/4 full, and the motion of the screw is fast enough to overcome the natural flow of the liquid down, much like a leaky bucket elevator. The actual mechanics of this device is much more the realm of a fluid dynamics specialist. On 7/9/2010 8:53 AM, Oli Glaser wrote: > > -------------------------------------------------- > From: "Carl Denk" > Sent: Friday, July 09, 2010 1:28 PM > To: "Microcontroller discussion list - Public." > Subject: Re: [TECH]:: Archimedes Screw - wide range of modern uses > > >> Not, the ones I worked with (5 foot diameter, turning maybe a little >> faster than 1 revolution per second), but there is significant leakage >> between the screw and the tube. The working clearances for machinery >> that big, and without getting into costly tight tolerances are loose, >> maybe 1/2" or more between the screw and tube. >> >> On 7/9/2010 7:55 AM, Sean Breheny wrote: >> >>> Isn't the screw, when stopped, a continuous inclined plane so that >>> water poured in at one end would just run "downhill" around the turns >>> of the screw and out the other end? I did look at the photos and >>> that's what it appeared to me. >>> > I think it would if the screw were vertical. When it is angled, the > "incline" is no longer "downhill", so it's like a line of "cups" in series > moving from one end to the other (the screw is less than half full). > > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist