Bicycle with square wheels

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Talking about traction and braking. Maybe a bit of trouble turning.
Reply to
Offbreed
Thanks for posting that! I think that is really funny. The text refers to the "unsolved" problem of discovering a meshing contour pair which would be the same on the wheels and the road surface. Of course, the old fashioned round wheel on a flat surface would qualify, since a flat road is a circular contour of infinite radius. Thinking along the same lines, wouldn't a rack and pinion also qualify? And, as you say, Jim, traction and braking would be excellent.
Reply to
Leo Lichtman
Not really. As the article points out, it's really a tricycle.
Trouble with doing this as a bicycle is that when you turn the front wheel goes farther than the rear wheel. Which means that the square wheels are going to get out of phase rapidly.
Quite a bouncy ride then.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
Reply to
jim rozen
I'm glad you guys liked our trike!
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This is actually the MARK II. The first one was built in 1998. The "road" is the original. The MARK I was a modified bicycle. It was a reverse trike, with the two wheels in the front, and a single driven wheel in the rear. The drive was good, but the steering was awful. The new trike is an off-the-shelf unit, modified by Dave Bole at the Bicycle Chain in Roseville, Minnesota. Dave is a Macalester College graduate. He replaced the original fork with a reshaped one. We needed the wheel base to match the horizontal distance between of the vallies in the track. The wheels are mine. The original wheels turned out to be 0.28" too short per side. So, I got to make new wheels. The Minnesota license plate
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is also mine.
Ken Moffett Macalester College Scientific Instrumentation snipped-for-privacy@macalester.edu
Reply to
Ken Moffett
If you allow for a "little" slippage between the tire and the road, the steering actualluy isn't bad. The track is only about 8" wider than the rear axel width. If you turn very much, you're off the track and a lot of other physical forces come into play. :)
Reply to
Ken Moffett
Could you explain the difference between catenary and parabola as to the focus with sun light? I don't recall seeing the Lissajous curve (Wells 1991) before , I did it the hard way.
I get lost on how to make the curves in reality. Glass would be cool in halves. I've tried to buy them. Seems to me that the auto glass industry could make them easy.
Reply to
Sunworshiper
Not sure. Must be pretty close. Certainly, the derivative (erm, amount of bend in the wire/cable/etc. over a short length) is related to the stiffness and how much weight is bearing down on that point (equal to the cable between the opposing points).
CNC? ;-) Personally I'd make it by getting an equation, running a bunch of numbers to graph it on a piece of plywood, cut the profile and fit the, oh let's say sheetmetal to it. Cut a few such curves, get an English wheel and make body panels. :)
Tim
-- "I have misplaced my pants." - Homer Simpson | Electronics, - - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting and Games:
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Reply to
Tim Williams
"Sunworshiper" wrote: Could you explain the difference between catenary and parabola as to the focus with sun light? ^^^^^^^^^^^^^ The curve formed by a chain, supported between two points is a catenary. It occurs when the load is uniform with respect to the curve. A cable supporting a suspension bridge is a parabola. If is formed when the load is uniform with respect to the horizontal axis. A parabolic reflector focuses parallel light at a point. I don't know what a catenary does to light. Probably nothing. special.
Reply to
Leo Lichtman
I'm having a hard time visualizing this. If you start with a chain, then make the links smaller and smaller, does the catenary approach a parabola as the link size approaches zero?
Reply to
Jim Stewart
Jim Stewart > The curve formed by a chain, supported between two points is a catenary. It
No, because the load is not uniform with respect to the horizontal axis. Although the per-unit-length weight is constant, the form is a curve rather than a straight line.
Reply to
Ted Bennett
On 5 Apr 2004 16:02:15 -0700, jim rozen vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
I don't know if it was the April issue, but I remember many (30?) years ago in Popular Machanics's "sort of wacky" secion, reading that the US Army was working on trucks with square wheels, that had a cental axle gearing arangement that followed the principles applied here, but to the axle's travel in the wheel rather than the wheel's on the road.
**************************************************** I went on a guided tour not long ago.The guide got us lost. He was a non-compass mentor.........sorry ........no I'm not.
Reply to
Old Nick
On 5 Apr 2004 16:02:15 -0700, jim rozen vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
.....and OOC I looked for a reference. I did not get one, but dod get this
Reply to
Old Nick
"Jim Stewart" wrote: I'm having a hard time visualizing this. If you start with a chain, then make the links smaller and smaller, does the catenary approach a parabola as the link size approaches zero? ^^^^^^^^^^^^^ Actually not--as the links get smaller, the contour approaches the "ideal" perfectly flexible and perfectly uniform string, so it approaches a catenary. The reason for talking about a chain is that it has no stiffness to interfere with the curve. If the links are long enough to be significant, you will have a series of chords approximating a catenary.
Reply to
Leo Lichtman

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