Tracked vehicle construction?

[unjonharley]

This is just a test http://community.webtv.net/unjonharley/doc1

My girl holding the the baloon cap while it is filling. She is a trained navigator. also lic. to drive in any country

[dragonfly Jafe]

How about taking a look at a "BOcats Front Loader" steering control. Or as far as that go's. There speed/gear control. It uses a expanding pully. There is a lose of torque but a study could help. Might get hold of a expanded, parts view of the thing.

Unjonharley, meeting you was a rare high point this year. Thanks for the discussion, I relish others views on mechanics, and you are obviously a genius there. I too wish I could have met your son, but from Thursday on I was on pain killers and enforced rest. It was all I could do to make it to the JOTS.

Using variable pulleys was my first design concept, but there is a max 40% variance in speed, and I really wanted to be able to spin in place since I had no reverse gear. I still think the DDSS system is the way to go, just beef up the frame 1000% (yes, 10x) and make the treads stronger. This WILL work if it is done right.

[unjonharley]

Tiahaar's machine

http://community.webtv.net/unjonharley/doc6

[unjonharley]

This is the one I like for a playa model.


Lone Sentry: Light Armored Half-Track (WWII Tactical and Technical Trends, No. 51, October 1944)

[spectabillis]

oh yeah, got to meat jafe and he is cool-as-fuck in my book.

i guess i could tell you and tiahaar sorry that it didnt work out, but if tiahaar has your attitude its not needed. its a rare and amazing thing to watch someone build something, things dont go their way, and instead of calling it a failure call it a success of achievement for the attempt in the first place. yep, how many people you know have even dreamed of attempting something that has not been done before?

besides, its the static minded of this world who dont learn from things not working.

[dragonfly Jafe]

Today I start removing useable parts for next year, and cutting up the frame. BioTrak is finished, but I am already starting to design BioTrak II...

[unjonharley]

D F JAke, I'm trying to get a picture of a halftrack called the Lone Sentry it is a one ton German personal carrier. "Trying". The key board died, droped it, started working, printer run out of ink, half way, halfpicture of halftrack.

Have to print it then scan it back. It is worth the though for design
My ric-shaw of 05 died driving onto the trailer The controler burned out. Brought it to BM anyway. Lots of people took pitures. I have new and improved ric-shaw for 07 in parts in the shop right now.

[dragonfly Jafe]

.... a quick Google search turned it up. Pretty cool, thanks for the suggestion. I am thinking along the lines of a "Kettengrad" tho' - single front tire, 2 small tracks, with enough room for 1 passenger and a cooler. And maybe a flame system for exhaust stacks....

[Elliot]

.
I did come across Tiahaar and his exercise-machine powered tracked vehicle. It is just as impressive as Jafe's tank. Tiahaar also had trouble turning, but it did move forward -- slowly.

It was an honor to meet Jafe and Tiahaar and Gravity Mike (again) and many others. Keep up the good work!

"Henry Ford Goes Surfing" was used in the Critical Tits Ride. They started at the tail of the ride and just barely kept up, but they made it. That's your goal for next year, guys!

[Gravity Mike]

Tiahar and Dragonfly, sorry I missed you guys - wished you both had better luck. Your tasks were no small undertaking. I think it takes 3 years to get something perfect on the playa; the second year works pretty good but three to get it right.

Elliot, on the other hand, I bumped into nearly every day! Elliot, you never made is by Citrus Camp, but Henry Ford Goes Surfing was parked in front many times - apparently the lady's you loaned the ride to had a great time in our bar.

Dragonfly, you're right about hammering welds. I had around 20 miles on my reverse trike before a weld in the steering linkage broke. I was able to drill a hole through and use a bungy hook as a set pin. Lots of slack in the steering, but it worked for my wife (and camp ice runs).

See you next year - and hopefully at the KSR in May!!!

Gravity

[Tiahaar]

Hey we're back on-line, horray! Wow has it been three weeks since exodus already?? I am already psyched for next year. Jafe, sorry to hear of your layup out there hope you are recovered, I saw your rugged beast out there and decided its just as well I stayed out of range...here's what might have been:

Elliot! Loved both your chopper monster-wheel cycle and the Henry Ford mobile! You have me hunting for a used set of drag slicks/tires for Project HPV 2007 (you cunning devil). Unjohn! Great to have you camped close by and jaw with you this year, always a pleasure. Gravity Mike, Spectabilis, all the rest of you Kamp Apokaliptika minions who missed out on a tank battle...ummm...sorry!! I could have done ok in a 100x100 foot ring...maybe...but getting over to 3 o'clock from F and 8:15 would have taken half a day, starting Wednesday morning when I finally got the TerraKrawler operational. Then I was aiming to do a Thursday night run over that way via Esplenade but only got 100 feet from camp before turning back. Decided to save energy for one big burn night trip...then cashed that in too. TerraKrawler was able to go forward and back but took WAY too much power in the tracks because 1) they were tight and preloaded the suspension even like a string on a bow (and my attempt at converting one double bogie to a single kind of worked in that it slacked the chain but the wheels were then spaced too wide and got hung up on the track bolts) and 2) damn that playa surface is NOT slidey enough to skid stear on!!! LOTS of friction...geez in three years I hadn't really appreciated that. I could do fine on grass, probably great on sand or deep dusty dirt. Finally 3) the thing was just too heavy with the dome, battery, speakers, deck, exercise machine...time for a diet.

There is still hope! I'm working at doing a conversion to a tandem recombent pedal power no-frills system. If it works, TerraKrawlerII will be back to BRC. But next year I have a backup plan in a nice big tall fat-wheeled trike project. Let the building begin! Tiahaar

[unjonharley]

Good mornig all, What I did on my vacation from Eplaya.


  
Including page: http://community.webtv.net/unjonharley/doc7


REading up on tracks. The U S half tracks were made of Two cables with rudder cleats vulcanied to the cabels. While the Germans were metal and each cleat had pin bearings. Very hard to repair in the dirt.

[dragonfly Jafe]

...my first idea for BioTrak was to use cables with the cleats strung on, with spacers in between. I figured the forces would be too great and "bunch up" the cleats. One advantage of this method is that you can build the sides of the cleats up as high as you need to keep the tracks in-line. In any event, using attachment chain worked well, although I should have tried harder to find steel 3/16" rivets (rather than waiting for the last 2 weeks). I have it waiting for my next tracked project, although that might have to wait a year or two.

I think my biggest failures were in building very weak bogie wheel assemblies that allowed twisting, using rubber wheels (without some sort of metal or wood inner "washers"), and not having a second sprocket at the rear to ensure proper alignment. Also relying on my arm muscles for turning...(if a persons legs are 1/10 hp, what is one arm? maybe 1/30 hp?) Still, even I could turn BioTrak (between 800-1000 lbs weight) although slowly...and there were issues with BioTrak climbing out of the tracks during turning (the 1" chain height was not enough to prevent the rubber wheels from climbing over - a "washer" between the wheels and chain may have helped prevent the wheels "gripping" the chain). My drive tensioners also wasted alot of the turning force - next time I will use teflon chain tensioners that do not rely on tightening the chain (and building in a "spring"). Built properly, the concept would definately work.

I agree with Tiahaar's assessment of the Playa friction - it was much higher than I anticipated - I had assumed it would be relatively easy to turn on.

And thanks for posting the TerraKrawler photo - I never did get to see it in person....looks awesome!

[unjonharley]

How about tieing knots in the cabel? Maybe use car or truck tires to make cleats?

[StevenGoodman]

>>>I agree with Tiahaar's assessment of the Playa friction - it was much higher than I anticipated - I had assumed it would be relatively easy to turn on. <<<

Actually, now that I think of it I should have been able to tell you that! From talking to people who drive cars fast on the playa; in general you don't want to try quick turns. There are many stories of quick turns and flips.

Now, if you wet the playa as you turned it would probably be really easy?

[spectabillis]

Elliot! Loved both your chopper monster-wheel cycle and the Henry Ford mobile! You have me hunting for a used set of drag slicks/tires for Project HPV 2007 (you cunning devil).

yep, you and several others i know. that thing made quite an impression.

and glad to see ya back

[phil]

Here's a playa-ready tracked vehicle:
http://www.engadget.com/2006/10/13/batt ... ashington/

[Toolmaker]

And thats one of the MANY reasons why I dont like bots.

[unjonharley]

Trying to come up with a slip disc between the drive and final drive. Maybe a sliping clutch, for a differential action.. For a pedaled half-track.

What the hell am I talking about?. I figured it ou while posting this. If I use a spring loaded two plate system the torque on the inner wheel will make it slip. If the torque is to much i can always add a lever to assist it.. Like on a farm tractor.. Tho instead of a brake the lever would lighten the tension on the spring load.

That should be about as clear as mud to you.

[unjonharley]

Trying to come up with a slip disc between the drive and final drive. Maybe a sliping clutch, for a differential action.. For a pedaled half-track.

What the hell am I talking about?. I figured it ou while posting this. If I use a spring loaded two plate system the torque on the inner wheel will make it slip. If the torque is to much i can always add a lever to assist it.. Like on a farm tractor.. Tho instead of a brake the lever would lighten the tension on the spring load.

That should be about as clear as mud to you.

[Tiahaar]

Hey guess what 8 months later I got the tracked rechristened StarKrawler monster up a parade route! YeeHaw! (pantpantpantwhewmomma). 6 people took turns pedaling and several others helped push it up the steep spots (they run this Santa Barbara Solstice Parade UPHILL aaaughhh) but it made it
One photo for good memories:

More photos at my friend's flickr set: http://www.flickr.com/photos/sithsnoopy/sets/72157600458311093/

[MikeVDS]

Beautiful and awe inspiring. Glad you got to share that with the parade and us with the update.

[LeChatNoir]

Woo HOO!!!

Nice work. I love the tracks and stuff sticking out at odd angles. Good to see an idea turn to reality and drive up the road.

Lucky for Earth that we use such creative powers for good...

[unjonharley]

You are a real contraptioneer

[Elliot]

Woo-hoo, indeed!
So... I'm just waking up, but... now it has two sets of bicycle
pedals instead of one rowing machine?

Well, you rode in a parade -- that means you are hooked on
that for life! I ride in every parade I can get to. Great fun!

[Tiahaar]

Thanks everyone, it was a lot of fun (and sweat and fried legs) but like I told a friend from now on any pedal thing I build has to coast on a flat surface and roll BY ITSELF down the slightest incline harumph : )

P.S. Elliot a nice lady gave me a card announcing the 10th Annual Ventura Harbor KSR October 27, might just get into it! (nononooo not the trak...but maybe the new trike)

[Elliot]

10th Annual Ventura Harbor Kinetic Sculpture Race October 27,

I'll be there, with several contraptions.

[carmatic]

hello guys, and merry christmas
i hope that you dont mind me dredging this old thread up, but i think that it is possible to create a pedal-powered tracked vehicle which can be steered in a relatively conventional way, not involving turning a crank to turn the vehicle
as in, rather than using 2 seperate sources of motion and power for steering and forwards motion, it is possible to divert the motion from a single source, i.e. the foot pedals, to cause the vehicle to move and turn

it depends on the use of a pair of CVT's meant for bicycles, with the ability to gear from 1:1 to almost nil output... CVT's are becoming more and more popular nowadays , so it should be easier to get a pair of them... and you also need some method of actuating the CVT's from the rider's position

the idea is , by having a pair of concentric gears, one inside another, rotating in opposite directions, and with planetary gears connecting them... if both of the gears are rotating such that the linear velocities of their teeth are equal, the planetary gears will be at a standstill... however if one of the concentric gears is slowed down or sped up, there will be movement of the planetary gears
it is this movement of the planetary gears which will drive the driven wheels

therefore, if one of the concentric gears is geared directly from the input , while the other is geared via the CVT's, and the CVT-driven gear can rotate twice as fast as the directly driven gear, the driven wheels can rotate both ways at equal rates depending on the ratio of the CVT's

here is a diagram i have slapped together, hopefully it will not hinder what im trying to say... this is one side of the transmission, the other side will be a mirror image

the numbers next to the gears mean their relative number of teeth, and the colours filling them represent their different rates of rotation
1. the cyan gears are the input, driven directly from the chain from the foot pedals
2. the magenta gear is merely turning in the opposite direction of the cyan gear, this is the input of the CVT
3.the yellow gear is the output of the CVT, as denoted by the variable x representing its ratio

with those points out of the way, lets ignore the movement of the large dark blue gear for now, associated with the ratio 1/2c ... imagine, instead that the gear is fixed, it does not rotate, as in c = 0 ...
the dark brown gear is a differential gear, it's rate of rotation will be the average of the two gears connecting to it... since one side has 0 rotation, it will rotate at half the rate of the gear turning it
therefore, it rotates at a rate which is a quarter of the CVT output, but because it has twice the radius, its linear speed is 1/2 that of the CVT output
the orange gear, which is the outer concentric gear, will also be rotating with a linear speed that is 1/2 of the CVT output...
and to mantain the ratios needed for the wheels to be driven in both directions equally, the portion of the purple gear inside the orange gear, that is, the inner concetric gear, will need to spin at a linear velocity 1/4 of the cyan gears
therefore, nominally, d = 1/2 .... the relative linear speeds of the axels of the plantary gears will then correspond to (1/4 - 0)/2 = 1/8 in the forwards direction, (1/4 - 1/2)/2 = -1/8 in reverse , and obviously (1/4 - 1/4)/2 = 0 , which is geared neutral ... notice that i use positive numbers to mean forward motion, and negative numbers to mean reverse


i dont know how many of you would have read this far... but you will notice that using the transmission involves constantly turning 2 different sets of small gears, the spider gears in the differential, and the planetary gears driving the output... this causes friction, and it is inefficient...
this is why there is the gear combination in the bracket with a combined ratio of 2/c , it creates a 'forward bias' in the concentric gears , in the sense that when the CVT outputs are slow enough, it will cause both the concentric gears to rotate in the same direction, and minimize the friction caused by the planetary gears ...
this applies to the brown differential gear too, since the slower the CVT outputs, the slower the spider gears in the differential turn... however, the higher the value of c , the more it offsets this effect since it rotates the other side of the differential in the opposite direction... hence c will likely be a low value
the forward bias would throw the ratios off, and to mantain equal forward and reverse speeds, with c > 0 , d would no longer be 1/2 , etc etc... i am leaving c and d , as well as the teeth ratios of the un-numbered gears, open to interpetation , since gears only come in integer amounts of teeth, gear ratios can only take certain values, and different people might prefer different amounts of forward bias or have different space requirements etc... i chose 2 as an arbitary ratio for some of the gears to demonstrate the concept
also, the other purpose of c is to counter the minimum ratio that the CVT's can give, since they do not actually give 0 output ... the values of c and d will have to be adjusted to accomodate for this

so the vehicle will travel faster forwards than it does in reverse, unless the CVT's are also able to overdrive, which in that case the vehicle is still more efficient going forwards due to the lower amounts of internal movement
here is the same diagram in terms of linear speeds, rather than rates of rotation, i hope it makes it easier to understand


now i dont know if any of you would have even reached this far, but for those of you who are still with me, you will notice that with the presence of the very large gear in the transmission, it will be turning at the rate of c , which as i have said is likely to be very low... if the gear extends off the right of the diagram i.e. across the center of the transmission, you could use the middle as a sort of pinion gear to drive much larger gears, resulting in very high torque... this can be geared to different applications which are torque-based, such as a winch...
so imagine, a pedal powered tractor with full manerverability and enhanced forward mobility, with a pedal powered operating winch... i can see it being used in festivals as a sort of mantainence vehicle

[carmatic]

playa-specific topics

>>>I agree with Tiahaar's assessment of the Playa friction - it was much higher than I anticipated - I had assumed it would be relatively easy to turn on. <<<

Actually, now that I think of it I should have been able to tell you that! From talking to people who drive cars fast on the playa; in general you don't want to try quick turns. There are many stories of quick turns and flips.

Now, if you wet the playa as you turned it would probably be really easy?

the reason your tracked vehicles are having such difficulty turning is not just because of the grip on the surface, but because the vehicles lack the lateral leverage to overcome the vertical axis torque resistance of the track against the ground... in other words, your vehicles are not wide enough... this isnt going to reduce the side loads on the tracks and bogies tho, in fact the greater leverage means that you can damage your vehicle with less effort, avoiding sharp turns is basically the best bet against such a risk
the best thing to do is to reduce the side loads from friction, and rounded cleats which dont 'dig into' the ground with their side edges would help, the best thing i can think of is a massive bulk order of suitably shaped cupboard handles...

also, the playa is very windy... and my transmission design can work well with a constant input rate...

therefore, if the vehicle is scaled up greatly such that no single human can power it, perhaps because it is also being used to carry large loads, it might be big enough to fit a couple of vertical axis wind turbines onto it...

these things basically spin on the spot, and a bunch of them can just be geared together via differentials and maybe one-way bearings to drive the larger vehicle's equivalent of the foot pedals ... not to mention, the very presence of the wind turbines means that wind energy can be harnessed by electrical generators onboard the vehicle and stuff, but that's getting off topic...

all you'd need is a person working the 2 CVT's , and maybe operate the winch or any other torquey auxillary devices, and you'd have a totally wind-powered vehicle capable of doing heavy work

Grease is less runny out of seals but induces drag, and may not get into the bearings.

one more thing about the gearbox and grease/oil .... perhaps you could coat the seal with grease, so that you get a real seal, and get lighter weight lubricant which will not dissolve the grease, and use them on the gears?

[ibdave]

My Head Hurts now...