View Full Version : paraffin, hydraulics, and diesels

08-17-2001, 01:43 AM
Gravity. The freon tanks rebalance the array I presume. Same idea for the garbage bag wheel. When heated the stretched garbage bag plastic shrinks a bit. In the case of the wheel it continually throws the wheel off balance, causing it to rotate.

04-17-2004, 10:03 PM
I'm glad nobody here knows exactly where I live, or somebody would likely come over and put a straight jacket on me and ship me off. Anyway, I have always wanted to make an extremely slow speed engine just for the heck of it. What I had in mind was wax filled cylinders, which would be alternately heated and cooled. I know that vehicle thermostats rely on a wax pellet element, and I have made such a cylinder filled with ordinary wax, and it works. The extension ratio over the heating/cooling cycle is about 10%. In other words, for a 2 in long cylinder, the piston will extend about 1/4 in or so. It's likely that the thermostat wax has a higher expansion ratio, I don't know. I'm wondering if there is a fluid that behaves this way, and if there are any applications other than thermostatic valve actuation. ?
By the way, my guesstimate is that red-line for such an engine would be around 1 rpm. The torque would be very high though.

04-18-2004, 12:23 AM
You are going to need a flywheel the size of Toronto's collective ego to carry it over TDC. Or use at least three cylinders.

You can also make an engine using stretched garbage bag plastic. Try this. Take a black plastic garbage bag and cut some strips about three inches wide, all from the same direction. Grab them at the ends and stretch them to almost the breaking point. Take about six of these strips, insert a lightweight strip of material in the middle of them (balsa works well) and twist the ends in opposite directions while putting them under tension. Hold them that way. You will have to make some sort of simple jig. Then flash them with a camera flash and watch it turn. By using strips like this as the spokes of a wheel that is exposed to sunlight on one half and shadow on the other you can make a simple motor. It turns REAL slow. You need good bearings.

[This message has been edited by Evan (edited 04-18-2004).]

Mike W
04-18-2004, 03:54 AM
You guys have way to much time on your hands. http://bbs.homeshopmachinist.net//biggrin.gif

04-18-2004, 04:25 AM
BTW Darryl, Chilliwack ain't that far from here.... You can be found. I have some bungees http://bbs.homeshopmachinist.net//biggrin.gif

04-18-2004, 03:54 PM
That's a neat trick with the garbage bag material, Evan. I'll have to try that one day. Years ago I saw a similar thing that just sat out in the sun and turned slowly. Yeah, something to do for someone with too much spare time.

04-18-2004, 04:35 PM
While you guys are laughing?

How about adding this ideal to the photo-cell ideal on the other page?

A buddy of mine made a sun-tracker with two freon cylinders, then cut two shades to partially block them.. the tracker when the sun climbed out of direct contact put a shadow on one side, this cooled that side and expanded the other side putting the liquid (common connection) to the cooler side, this rocked the collector to follow the sun. Equalized the sun when both shined on..

He had tried sun clocks and other items..


04-18-2004, 08:58 PM
I sort of understand what is going on here in the sun tracker, but I'm stumped as to how your friend translated the movement of the liquid to the movement of the collector.

I figure to build a solar collector down the trail, and I'm gathering ideas and information for when that time comes. Could you give a few details so this blockhead can understand?