Tracked vehicle construction?

Elliot · Post by **Elliot** » Wed Jan 11, 2006 6:30 am

.
I'm a sick man. I actually awakened myself with the realization that I coined this word last night, but didn't...

Jafe! You are building a Katzenjammerrad!

Katzenjammer = caterwauling.
The Katzenjammer Kids = famous classic comic strip about two fabulously mischievous and inventive kids.
Rad = wheel, bicycle.

Now we need a comic strip buff to find us a picture of The Katzenjammer Kids with a tracked vehicle. It is one of the world's oldest comic strips. I grew up with those brats. Those kids (Knoll og Tott in Norway) were always building Rube Goldberg devices -- like slapping an outboard motor on a bed and sending the sleeping person out to sea. They must have had some sort of tracked vehicle at one point. Somebody!? Anybody?!

robotland · Post by **robotland** » Wed Jan 11, 2006 6:37 am

Ja, I too grew up reading the exploits of Hans und Fritz, plus Little Nemo AND Rube Goldberg...and Krazy Kat looks like it was drawn right out on the playa.
Even though I'm in the Ten Percent Comprehension Club about the drivesystem details, I'm STILL getting enough inspiration from this thread to create a proper MUV. Keep up the good work!

Elliot · Post by **Elliot** » Wed Jan 11, 2006 6:58 am

Thanks, Howdy -- I was afraid I had gone too far into outer space!

Now -- I'm still only half awake -- MUV?

Howdy, you can build a "tank" out of two bicycles and three simple crossmembers to keep them parallell to each other.

This guy actually runs tracks on his "duck", but I don't have any picture of it with the tracks on. (His tracks don't work worth a hoot, but they have great theatrical value.)

Now search those comic strip archives, will ya! There's high jinks and hilariousity to be had here!

Elliot · Post by **Elliot** » Wed Jan 11, 2006 7:50 am

Oh so close: http://tegneserie.info/knoll_og_tott_1928.htm

Lassen Forge · Post by **Lassen Forge** » Wed Jan 11, 2006 8:37 am

Be careful hanging out at the Towe - you can get serious ideas from that place!!!

I thought - really seriously - about figuring a way to use a snowbird kit... you can still find them occasioanlly on eBay and on the model T swap sites (don't ask how I know *that*!!) but they're a few thousand $$$...

I have no doubt it would work, tho - T's were out in that nasty enviroment doing hard work for decades... and I've seen those same conversions used in desert dituations...

Hmmm... now you got me thinking. Bad Elliot!!! >giggles<

bb

Elliot · Post by **Elliot** » Wed Jan 11, 2006 8:48 am

1: Too late -- I'm a docent at the Towe (well used to be, and I took many of the photos on the web site -- toweautomuseum.org.)

2: Playful thinking seems to be why I'm not getting any work done this morning!

3: I like being bad and making people giggle!

regionalchaos · Post by **regionalchaos** » Wed Jan 11, 2006 10:04 am

Damn, I like this one:

Elliot · Post by **Elliot** » Wed Jan 11, 2006 10:23 am

.

That is "Unwheeldy". It was awarded the FIRST EVER Honorable Mention for Engineering at the 37th Annual Grand Championship Kinetic Sculpture Race in Humboldt County, Northern California, last Memorial Weekend. This was its first outing, and it broke down, but the judges felt that Recognition of Achievement was called for and created the new award on the spot. The bugs have since been pretty much worked out. Unwheeldy remains difficult to steer, however, as it has NO steering mechanism whatsoever (hence the name!). It is a two seater, and it is steered simply by telepathic coordination between the pilots, who drive one wheel each.

He has a web site... try this: http://www.scrye.com/~hersh/ksr-entry/

Bob · Post by **Bob** » Wed Jan 11, 2006 11:09 am

http://images.burningman.com/index.cgi?image=169

Elliot · Post by **Elliot** » Wed Jan 11, 2006 11:48 am

.
There ya go! A lot of Kinetic Sculpture Racing Contraptions are also little more than a bunch of bicycles, reconfigured. You stock up on bikes at the thrift shops for five bucks each and just start nailing them together -- sometimes literally. Here is one from the Ventura Kinetic Sculpture Race a few years ago -- just two bikes and some lumber and rope. Well, mostly... In the center you see the wood pontoons that go on the ends of the arched crossmembers for water travel.

Bob · Post by **Bob** » Wed Jan 11, 2006 1:13 pm

Track, vehicle, bla bla bla... just don't make it too much of a competition...

http://images.burningman.com/index.cgi?image=4370

Elliot · Post by **Elliot** » Wed Jan 11, 2006 1:53 pm

.
Good point. And I am happy to report that at these silly Kinetic races I talk about, we place a much higher priority on theatrics, innovation, pageantry, art, audacity and so forth, than we do on speed or other forms of traditional competition.

For example, at the Port Townsend, WA, race, they give the top price to the team that finishes smack dab in the middle of the pack. Much of the scoring is based on "tickets" (as in speeding tickets) issued along the way -- a friend of mine got one for "Incomprehensible gear system" (which may have been positive or negative points, depending on....)

About those two guys in the straw hats above -- there were about eight of them on the team. The rules say you may not change riders during the race. The sand dune segment of the event ran down the beach and back to the starting point. They BURIED one of their guys in the sand, just face sticking out, at the turn-around point. When the vehicle came by, the "fresh legs" jumped out of the sand and onto the machine and a tired rider was buried. All this in front of a couple hundred cheering spectators. We gave them the Racers' Choice for Most Audacious Cheating -- a great honor in this sport/hobby/art-form/behavioral-disorder.

Would this style of competition fit in at BM?

capjbadger · Post by **capjbadger** » Wed Jan 11, 2006 9:24 pm

Seems this has devoled a bit into a general art car construction type topic, so I'll ask here...

I'm looking at using some mountain bike style tires as the wheels for my vehicle. Does anyone know the lbs load limit for these (or where I can find the info)? Need it to do some math on this beast.. thanks

Badger

robotland · Post by **robotland** » Thu Jan 12, 2006 6:15 am

Elliot wrote:Now -- I'm still only half awake -- MUV?

MUV= "Mutant Vehicle"... or "Mutant UTILITY Vehicle", I suppose.

Elliot · Post by **Elliot** » Thu Jan 12, 2006 6:26 am

.
Badger, I LOVE YOUR AVATAR! Can you fix all the World's komputor gremlins like that???

"Load limit?" "Mathematics?" We don't need no stinking....(A moment later they were all dead.)

I confess, Badger, I flunked out of college over math. Can barely handle a tape measure. Use my vernier calipers as a hammer.

Engineering is a valuable, even necessary, skill. But I'm doing OK with eyeball estimates.

There is a famous joke about race car designer Colin Chapman -- creator of fast-but-fragile Lotus cars. The frame of these cars was a cage-like structure of many small steel tubes. Supposedly, he would first build a structurally well enginered frame for the car. Then, to reduce weight, he would remove pieces until the frame collapsed. Then he would put the last piece back in, and go racing.

Another confession: In KSR, we use the word "taco" as a verb. It refers to what happens to a bicycle wheel when it is overloaded -- it folds over like a taco-shell.

I overbuild everything, but they don't break.

Stick around, Badger, there will be info here soon, I'm sure. Gawwwwd, I want one of those computer-fixing critters!

capjbadger · Post by **capjbadger** » Thu Jan 12, 2006 6:38 am

hahahaha... Well I'm an ok computer tech, but after everything I've seen, real cats just piss on the motherboards.

(I love that pic too. Its just too funny how the cat pauses to look to see if anyone saw. lol)

The math I'm thinking of is pretty simple. Figure out the "taco point" *chuckle* of the tire, then divide the total weight of the vehicle by that number to find the number of tires I need to support it.

Vehicle Weight / taco point number = Number of wheels

If no one has the info, perhaps I'll use that Colin Chapman test. Take a tire and start putting weights hanging off the axle until the wheel tacos.
Hmmmm.... Sounds like fun. I think I'll do that test to *cough* double check any info I get..

Badger

Tiahaar · Post by **Tiahaar** » Thu Jan 12, 2006 8:01 am

capjbadger wrote:I'm looking at using some mountain bike style tires as the wheels for my vehicle. Does anyone know the lbs load limit for these (or where I can find the info)? Need it to do some math on this beast.. thanks :)Badger

Just think of a mountain bike, it can carry 300lbs, so 150 lbs per wheel would be my upper limit, say 100 lbs as a safer limit and maybe 75 as a working norm? The wheels are good for greater shock loads (like landing a jump) but only if both sides of the axle are supported like in a bike frame and the load is in the plane of the wheel. Its those side loads that will taco a wheel, you could go with heavier motorcycle gear if there's going to be some major movin' and shakin' going on.

Elliot · Post by **Elliot** » Thu Jan 12, 2006 8:12 am

Badger, the taco point will vary greatly with the amount of cornering force on the wheel. Also, you will often stretch and/or break spokes long before the tacos are served. In other words, this is all a matter of degrees.

Fundamentally, bicycle wheels are not intended for side loads.

It is common in KSR to add spokes to wheels. You just drill more holes and install more spokes. It is also common to assemble several bicycle wheels in a "sandwich" on one axle. (Why is this discussion making me hungry?

) Considering that you can purchase bicycles for as little as a buck at thrift shops, garage sales, lost-and-found auctions and so forth, it seems worth it to just experiment -- and keep some spare wheels handy.

I have friends who are expert wheelwrights. I'll see if I can find them on the web. (Edit) Naw... the site I had in mind is being reworked. But I see we have some numbers from Tiahaar. And how about you start a new thread and ask about wheel info!

capjbadger · Post by **capjbadger** » Thu Jan 12, 2006 8:27 am

Tiahaar,

Hmm... 75-100 lbs. I was afraid of that. I'm looking at a three wheel vehicle (picture a tricycle being ridden backwards so the steering is in the rear). I'm figuring that with that kind of setup, with the wheel pivioting without any leaning, the side load issue will not be a problem.

Doing some very rough estimates, I'm looking at 4 people being on this thing at once. Figuring 175lbs per person (to be on the safe side. I'm only 155lbs), thats already 700lbs. Plus the weight of the vehicle (I'm very roughly figuring 250-300lbs), I'm looking at half a ton... doh! 10 tires?!?

Elliot,

Yeah I was thinking about sandwiching wheels like you said, but I'm not sure I can do that many (plus I'm not sure how to do it other that weld a series of forks together, one for each tire).

I was looking forward to getting to use a cheap source of tires and the built-in gears for the drive train, but now I'm starting to wonder if this is workable...

Badger

Elliot · Post by **Elliot** » Thu Jan 12, 2006 8:41 am

Badger, it is when the wheel does NOT lean that you get side loads.

To visualize several wheels on one axle, think Shish-ka-bob (more food!) Then you add small metal straps between the rims with pop rivets.

The backwards trike layout is common in KSR. But for four people, you will definitely need more than three bicycle wheels. Motorcycle wheels are good, as already mentioned.

capjbadger · Post by **capjbadger** » Thu Jan 12, 2006 9:03 am

Elliot wrote:Badger, it is when the wheel does NOT lean that you get side loads.

To visualize several wheels on one axle, think Shish-ka-bob (more food!) Then you add small metal straps between the rims with pop rivets.

The backwards trike layout is common in KSR. But for four people, you will definitely need more than three bicycle wheels. Motorcycle wheels are good, as already mentioned.

oh! Looks like I didn't understand what you guys ment by side loads at all. doh.

(Damnit, now I'm hungry!

)

Ahhh... I've never tried to remove the built in axle of a bike wheel. That makes sense. Yeah, it's looking like I'll have to look into motorcycle wheels. bugger. I was looking forward to using them for easy gearing off a normal bike setup. I think I might of just got in over my head.. lol

Badger

Elliot · Post by **Elliot** » Thu Jan 12, 2006 10:02 am

Badger, I respectfully disagree with you; you are not in over your head at all. You are learning, which is a highly legitimate process! A few years ago I was scared of bicycle crank sets. Now I can tell you which brand is built to the closest tolerances (Schwinn -- in the realm of old thrift store bikes).

To my mind, Side Load is what you feel when you drive around a corner in a car. (Car racers talk about "side bite', meaning traction while cornering.) On a bike, you lean into the turn which eliminates the side load on the wheel, keeping the load at 90 degrees to the axle.

Were you talking about the kind of bicycle rear wheels that have gears inside the hub? The old Sturmey Archer 3-speed? I tried these -- made by Shimano in more recent times -- on The Two Ton Tricycle. Busted them all to heck in no time. (There are 7-speed and even 15-speed hubs now, but they are expensive.)

If I were to build some bicycle sandwich wheels, I think I would take the bearings out of the hubs and shove the largest possible (3/8?, 1/2?) steel shaft thru all the hubs. Then run that shaft in external bearings. Look inside a swamp cooler -- like the bearings the big squirrel cage fan runs in.

We could go on a long time here, and maybe accomplish something eventually! But I will be going incommunicado for a couple of weeks, starting tomorrow. And we are a bit off Jafe's original Tracked Vehicle... uh... track. Why don't you start a thread on wheel building and see who shows up!

capjbadger · Post by **capjbadger** » Thu Jan 12, 2006 10:49 am

New thread started.

regionalchaos · Post by **regionalchaos** » Fri Jan 13, 2006 9:04 am

Man, I think I'm going to have to go to the KSR scheduled for Corvallis. This stuff just looks like too much of a good time!

Isotopia · Post by **Isotopia** » Fri Jan 13, 2006 4:58 pm

Tracked vehicle construction? I'm not sure but..... this web link might have some information for an idea or two.

http://www.mattracks.com/html/105_series_.htm

Tiahaar · Post by **Tiahaar** » Sat Jan 14, 2006 11:46 am

Isotopia wrote:... some information for an idea or two.

Very cool, very expensive $$$, but free ideas, thanks! The pictured tracks are for a utility trailer, there are other driven track sets for trucks/ATV's on the site. I'm going with 1x4's bolted to attachment chain for my tracks at this point.

dragonfly Jafe · Post by **dragonfly Jafe** » Fri Jan 20, 2006 4:59 pm

...I have wanted one of those Mattrax sets for years - even looked into buying a set for my old SAR unit, but they are very expensive...and snow machines or ATVs do just fine, and there's no shortage of volunteers willing to provide theirs in an emergency for free...

Update on tracked vehicle;

I have decided to try 2" emt for the basic chassis with 1" emt for the uprights and front. The estimated weight is 85 lbs (chassis only). Cost should be around $40.

Seats, bicycle gears, wheels, and tracks will add another 65 lbs, for a total empty weight of 150 lbs. With 2 people and a cooler, total weight should be 550lbs (battery for lights add 50lbs)

The tank bits will add another 100-150 lbs when it is dressed up. With 3 people and a cooler, total weight should be ~950lbs (1000lbs w/ battery)

A possible hitch is the cost of new differentials...definately need to start scoping garage sales for cheapo lawnmowers (where do the Kinetic Sculpture Builders get theirs from? Which model/type works best?)

Elliot · Post by **Elliot** » Sun Jan 29, 2006 8:02 pm

Most of the differentials used in Kinetic Sculpture Racing are from old lawn tractors. Some guys buy them new from outfits like Northern Tool -- that allows them to choose quality level, such as bushings vs bearings, and perhaps power ratings. Go Karts use the same kind. Dead lawn tractors are everywhere -- on people's front lawn, at lawn mower shops, flea markets, recycling centers etc. That help any? Remember to mount these with bearings right next to the diff -- not way out on the axles which will cause breakage.

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Feb 01, 2006 9:41 am

...I was thinking that maybe certain brands/models worked particularly well for bicycle powered vehicles...that way I could focus my search for those brands/models...or is it true that most any riding lawnmower differential will work OK? Any models that definately SHOULD NOT be used?

The frame is done, I am anxious to start engineering the drive train...

I start building the tracks next week; I plan on using 2"x 1/8" aluminum flat stock cut into 4" lengths with 2x 1" angles welded on to form the wheel guides...I am going to test a few sections to verify it works as I think it should, then onto full-scale production! Only 150 tread pieces needed (plus a few spares), that should keep me out of trouble for a while...

Elliot · Post by **Elliot** » Wed Feb 01, 2006 10:26 am

Sorry, Jafe, I don't know much about diffs. In fact, I've never used one -- I like to have each rider power his own wheel. But lots of KSR builders use lawn tractor diffs, and I haven't heard of any common problems. I gave one to my neighbor, who proceded to build a horribly ugly and heavy Contraption from a boat hull -- but the silly thing WORKED GREAT! I doubt the diff(s) will be the weakest link in your Doom-Crawler. Keep up the good work!