Spherical Wheels

[Savagemutt]

Back to the wheels, what movie/show was it where each axle hub consisted of three, almost spherical, tyres set in an equilateral triangle configuration with a centre pivot? As it hit a bump/rock the triangle of wheels would rotate. Hard to describe but difficult to find a picture without remembering the movie/show.

Are you thinking of Damnation Alley?

 

[alfaniner]

Back to the wheels, what movie/show was it where each axle hub consisted of three, almost spherical, tyres set in an equilateral triangle configuration with a centre pivot? As it hit a bump/rock the triangle of wheels would rotate. Hard to describe but difficult to find a picture without remembering the movie/show.

The vehicle was also used in the Saturday morning live-action "future" show Ark II.

 

[exarch]

Originally posted by Savagemutt

Originally posted by H3LL
Back to the wheels, what movie/show was it where each axle hub consisted of three, almost spherical, tyres set in an equilateral triangle configuration with a centre pivot? As it hit a bump/rock the triangle of wheels would rotate. Hard to describe but difficult to find a picture without remembering the movie/show.

Are you thinking of Damnation Alley?

It seems like a bumpy ride though (although you wouldn't know it from the interior scenes that were of course shot in a studio).

 

[richardm]

Bad ride, and they're really bad for the roads.

Can't imagine that they'd do much for fuel economy either.

 

[Bruce]

A circular area actually, but I don't see how this would be a problem. In fact, a circular area would provide equal friction in all directions, while a rectangular area gives far less friction in the direction the wheel is rolling compared to the sideways friction, which is why emergency breaking can make your wheels start sliding.

On a single point, yes, but tires are slightly elastic, which would make the point expand to a circular area, with probably about the same surface area as a normal tire. In effect, a cylinder centers the weight on a line, and touches that line every full revolution of the wheel. Also, it only touches the running surface, while a cyllindrical wheel would touch the same point on the tire less frequently, but the 'side' of the wheel is also a running surface. I'm sure wear on the tires would be spread out over a larger area of tire than on a conventional cyllindrical wheel that only wears the running surface.

Tank threads produce far too much sideways friction when turning. Even ordinary car wheels already create quite a lot of friction when being turned. And threads have way too much surface area for what a normal car really needs for normal road use. Look what happens when you only increase the tire width without increasing the weight: less traction because the vehicle has less weight per surface area than a thinner tire, which is deadly on a wet and slippery road. Also, more effort is needed when turning the wheel while standing still (i.e. during parking and other manouvers).

The reasons tanks have threads is because they mostly run on unpaved surfaces, where ordinary wheels are of no use (like mud and rough terrain). Tanks are also really heavy, which is why a tank thread is ideal for spreading all that weight out over a larger area.
By the way, tank threads roll on a set of wheels

I can't explain why, but I just love being totally shot down and debunked. Thank you sir, may I have another.

 

[shecky]

The only advantage of a spherical wheel/tire is that it would be less likely to get bogged down in sand, having such a wide contact patch with the surface. Think back of those old Honda ATC 90s, with very wide, low pressure balloon-like tires. Such wide tires have a snowshoe-like effect on such soft surfaces.

On hard ground, the contact patch would be roughly round, as opposed to rectangular. Assuming a reasonable amount of flexibility, I suspect they could offer as much traction as any conventional tire. I guess they'd wear disproportionately along the centerline, so the anticipated contact area would have to be much thicker than the "sidewalls" to counter such wear.

I'd think there would be more steering linkage difficulties, since a spherical wheel would be significantly wider than a comparably sized conventional wheel. The wheel would arc over a much wider area since the sterring pivot is further from the centerline of the wheel. Unless the steering was engineered significantly different than typical. Perhaps if the wheels were mounted on a fork and the steering pivot was above the wheel, rather than next to the axle.

Wider wheels would also mean either a wider car or less room inside to accomodate the extra width.

 

[Paul C. Anagnostopoulos]

Wait a minute! The purpose of spherical wheels would be so that you can drive in any direction without turning the car, right? Otherwise, why bother?

~~ Paul

 

[exarch]

Originally posted by Paul C. Anagnostopoulos
Wait a minute! The purpose of spherical wheels would be so that you can drive in any direction without turning the car, right? Otherwise, why bother?

Indeed.

Shecky, the idea of spherical wheels is that they have NO axle, they can rotate freely in all directions. That's also why SkepticJ was asking how those would be steered and spun up to speed.

As I said before, using magnets seems like the most obvious choice, since anything physically touching the 'ball' would probably create more friction and wear the tire faster than just having a conventional wheel with a rotational freedom of 360 degrees around a vertical axis (which by the way has been tried I think).

Bruce, it wasn't my intention to shoot you down like that, I was just brainstorming a bit. Sorry
Feel free to shoot me down in return if you find something wrong with what I said

 

[H3LL]

Thank you Savagemutt.

It just shows how memory deceives. I thought the wheels were much more spherical.

Enough de-rail...back to the thread.

Image from bugeyedmonster.com

 

[H3LL]

This site is interesting. Although not spherical, they address the issue of omni-directional traction.

Inovative Wheels

 

[shecky]

Indeed.

Shecky, the idea of spherical wheels is that they have NO axle, they can rotate freely in all directions. That's also why SkepticJ was asking how those would be steered and spun up to speed.

As I said before, using magnets seems like the most obvious choice, since anything physically touching the 'ball' would probably create more friction and wear the tire faster than just having a conventional wheel with a rotational freedom of 360 degrees around a vertical axis (which by the way has been tried I think).

Ahh, I see. (I haven't seen that movie)

What a odd idea. Seems like magnets, while possible, wouldn't be the ideal way to go about this. Wouldn't the wheel itself need to be significantly magnetized? Which would mean picking up all kinds of debris from the road. Braking and steering would demand some extremely strong magnetic fields. I think even if you somehow managed to come up with a non-magnetized sphere inside a magnetized wheelwell, debris from the road would end up getting wedged between the wheel and wheelwell.

Such a wheel would need to have a compliant, probably rubber, rolling surface if it's to grip the road surface at all. And even if you can magically get a appropriately durable wheel to essentially float in a wheelwell without significant magnetics, and still be able exert enough lateral and reverse rolling forces on it to be able to steer and brake effectively, why not just get rid of the wheel altogether and use the magical forces to make the whole vehicle float, like Luke Skywalker's land speeder?

Maybe something more like a upside-down trackball assembly could actually be doable now. Of course, friction would be much higher. Might work well enough for something like a mobile la-z-boy chair. But seems untenable for a relatively large vehicle needing to move at high speed.

Now, this thing I DO remember. In fact, I seem to recall it was parked in a lot for years off the Cahuenga Pass near Hollywood. No kidding!

 

[Bruce]

Bruce, it wasn't my intention to shoot you down like that, I was just brainstorming a bit. Sorry
Feel free to shoot me down in return if you find something wrong with what I said [/B]

No, don't apologize, please. I was being fecitious. I don't know if you're any more of an expert in physics than I am, but if you aren't, you've fooled me. I wish I could have some intellectual debates like that with the people I work with. Most of the people I know right now just accept whatever I say without question, or try to counter with ignorant rambling. Reading a plausible counter to my half-assed scientific analysis is very refreshing indeed!

 

[Matabiri]

Maybe something more like a upside-down trackball assembly could actually be doable now.

You mean like a... a... a mouse!?

 

[H3LL]

Now I'm just airing a thought here...so be kind

I was thinking that a linear-motor system may work.

This would mean the core of the wheel could be aluminium. I remember Professor Braithwaite demonstrating a sheet of aluminium floating on a track many years ago during one of his xmas lectures on TV (do they still have them).

Magnets may be better as with mag-lev but presents the debris collecting problem mentioned earlier.

The coils could be arranged to enclose most of the wheel, at least some way past the 'equator', and either mechanically rotated (maybe smoother steering) from the 'pole', or there is perhaps a solid state method to change direction within the coils.

The vehicle would not so much be 'on' the road as 'on' the wheels. There would be no friction problem (like the inverted track-ball) as the mag-lev/linear-motor would maintain a gap between the coil and the wheel arches and perhaps also give some level of suspension.

Brakes might be a problem. Reversing field direction might work with a clamp system as a failsafe. Parking brake would be just the friction between the tyre and the arches again with a clamp as a failsafe. No power, no levitation. Engine/Power failure would automatically stop the vehicle due to friction between wheel and arches.

Inflating the wheel would not be a problem, as we do it OK with footballs and basketballs and the valve could be located below the tread level.

Connecting the tyre to the core should be interesting in an inflatable version. Perhaps thin walls along the longitudes and latitudes but I think this will cause uneven wear and present a hard spot at the poles but there are other configurations of concentric rings that should work. A solid option seems the best way.

Designing a workable tread pattern may be difficult too, as the direction of rotation is (infinitely?) variable. Smooth racing rubber is an option but it has a short life and leaves the road sticky and has problems in the wet. I would really like to see an omni-directional tread pattern for a sphere.

I have no idea how you would change a tyre, but maybe not required with a solid one and where the heck do you keep the spare. A lot of wasted space.

Finally. Would the interior need to be shielded from the field? It would upset the woos..Then again, they may think it will cure any disease. Perfect for ambulances

©H3LL - Nov 25th 2004 (Just in case) .

 

[Matabiri]

Designing a workable tread pattern may be difficult too, as the direction of rotation is (infinitely?) variable. Smooth racing rubber is an option but it has a short life and leaves the road sticky and has problems in the wet. I would really like to see an omni-directional tread pattern for a sphere.

Applying the hairy ball theorem says you'd have points where the tread "merges", forming spots of different grip and wear. Unless you go for a hexagonal fullerene-style tesselation, I suppose. No idea what the water-shedding characteristics of such a tyre would be though.

 

[H3LL]

Applying the hairy ball theorem says you'd have points where the tread "merges", forming spots of different grip and wear. Unless you go for a hexagonal fullerene-style tesselation, I suppose. No idea what the water-shedding characteristics of such a tyre would be though.

I'll pretend that I understand all the maths about the hairy ball theorem and say thank you. That must be one of the wierdest names for a theorem around.

It was the water shedding characteristics that I was think of..Thanks for pointing that out.

 

[exarch]

Originally posted by H3LL
I'll pretend that I understand all the maths about the hairy ball theorem and say thank you. That must be one of the wierdest names for a theorem around.

It was the water shedding characteristics that I was think of..Thanks for pointing that out.

I don't know how tire-threads are designed today, but the idea is indeed to have little "gulleys" that the water can escape through, while the raised area's provide the grip 'through' the water on the surface.

On a sphere, I reckon tiny triangles might work really well ...

 

[Johnny Pneumatic]

I don't know how tire-threads are designed today, but the idea is indeed to have little "gulleys" that the water can escape through, while the raised area's provide the grip 'through' the water on the surface.

On a sphere, I reckon tiny triangles might work really well ...

Hexagons is what the tread was in the movie.
Does anyone know if Audi built the car with normal hidden wheels or spent a lot of money to build real working ball wheels? I'm gonna guess they went for the non working prop route.

What about the shocks? How could they attach to the socket that the ball is in? Or would the magetic fields that keep the ballwheel from rubbing the inside of the socket be used as the shocks?

 

[exarch]

Originally posted by SkepticJ
Hexagons is what the tread was in the movie.
Does anyone know if Audi built the car with normal hidden wheels or spent a lot of money to build real working ball wheels? I'm gonna guess they went for the non working prop route.

What about the shocks? How could they attach to the socket that the ball is in? Or would the magetic fields that keep the ballwheel from rubbing the inside of the socket be used as the shocks?

Well, for starters most of the "roads" in the movie are some kind of underground tunnels coated with something that's probably supposed to be next generation asphalt. Not much need for shock absorbtion there. Other than that, I'd suppose you could use ordinary regular shock absorbers, i.e. they are fixed on one end to whatever holds the wheel, and the other end is attached about two feet higher near the top of the car body. The spring inbetween, in combination with a hydrolic piston create the shock absorbtion. In other words, the whole magnetic wheel-enclosure moves up and down with the wheel. You could use additional magnets for the shock absorbtion while you're at it. But I reckon using the same magnets that control steering and drive for shock absorbtion will reduce the amount of control you have over the wheels.

 

[Globert]

The spherical wheel sums up the whole movie for me...balls.

Although a fun action movie, it was just another Frankenstein Complex movie that presented the exact opposite of what Asimov was trying to illustrate in his stories.



Back to the wheels, what movie/show was it where each axle hub consisted of three, almost spherical, tyres set in an equilateral triangle configuration with a centre pivot? As it hit a bump/rock the triangle of wheels would rotate. Hard to describe but difficult to find a picture without remembering the movie/show.

It was the Landmaster from Damnation Alley

my favorite car of the future.(who said fallout was bad?)

-Globe