Tracked vehicle construction?

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Dec 20, 2005 11:20 am

I examined Bob's site in great detail (and every photo on it of his wonderful device!) I still have some questions, however...

I am going to have to ask Bob for some hints (and definately attend one of these Kinetic Scuplture Races - they look like a real hoot for a gearhead like myself)

I think that if this system will work, I can get by with only 1 transmission (to shift the main collective axel into foward/reverse). That way I can use the differential steering system to rotate in place or steer, and the transmission to shift into reverse when I just need to back up (I imagine the DDSS would steer in reverse also). This would appear to be the elegant solution I have been searching for...thanks again!

Tiahaar · Post by **Tiahaar** » Tue Dec 20, 2005 10:37 pm

Interesting, Elliot! I share Jafe's fascination with this dual differential setup. What a splendid way to add power into the system selectively (rather than taking power out by braking one side of the diff.) to get one main shaft to turn faster than the other. Amazing

May I grovel for a tip??? How do you kinetic racers deal with the grease-packed mower transaxles to get the internal resistance of gears/grease minimized? I think I should have just cleaned out the grease and put in a quart of gear oil...but now its locked deep in my trike's frame. What could be added into a hole in the tranny top to "liquify" the grease...very light machine oil, kerosene, ???

Sidenote: just thinking...my '74 full-time 4x4 manual brags about the truck's 3'rd differential in the transfer case to send power to front or rear axles as needed...

Lassen Forge · Post by **Lassen Forge** » Wed Dec 21, 2005 9:58 am

You have to be careful that in changing from solid-base to fluid-base lube, it doesn't run out of the seals, which were designed for thick gooey stuff, not thin runny stuff.

Kerosene will dissolve it but will require agitation. Gasoline works better but then you're building a bomb. There are various flourocarbon solvents out there that will attack and liquify a lot of stuff, but it's pretty nasty crap.

If you're thinking about dissolving the grease and leaving the stuff in place, It'll work (I guess) but it's not really lubricating much. Your "lube" will be settling in the bottom of the case, what will be splashing around is the lighter solvent with trace ammounts of grease goo.

If it were me (and I haven't seen your trike, so it may not be feasable) I'd sure try to figure a way to be able to pull it out to swap the lube, and re-intall it. This way, when Murphy strikes, you'll also be able to take it out to fix it when it breaks. Then replace the output grease seals with a more positive oil seal at the same time, and use a regylar diff lube (85w or somesuch) or at least a lube oil that will not separate itself out. (FYI, Mercedes used to use 20w-20 oil in their gearboxes, and most Japanese bikes use Motor Oil to lube their trannies, so you may be able to go this thin).

bb

Tiahaar · Post by **Tiahaar** » Wed Dec 21, 2005 12:13 pm

Thanks BBSue, I was afraid I might be getting out on thin ice with kerosene so to speak, you confirmed it. Hmm. Back to the laboratory. The tranny is unboltable, just a long process, shortcuts always beckon. With the thing in neutral spinning the gears is about the same effort as riding a bike on level pavement at @ 10-12mph. (Bikram Yoga tonight!)

Gravity Mike · Post by **Gravity Mike** » Wed Dec 21, 2005 2:33 pm

Thanks Elliot and Dragonfly Jake for all the useful construction tips. I also have a fascination with a pedal-powered trac vehicle, but know that it's too much for me skill-wise at the moment. Not being a couch potato, I have to build something new, so I am working on a design for a railroad 'handcar' based on bicycles for '06. Steering is an issue, of course, as railroad handcars are steered by the rails, but overall this has far fewer serious technical issues than a bike-tank.

I also want to check out one of these kinetic scupture races! This is definately something I'm interested in. Keep up the good work!

Gravity

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Dec 21, 2005 4:01 pm

You could have fixed wheels on your hand-car and turn in the same fashion as my tank will turn - by using differential steering. In your case it is a bit simple because one or two persons can pump the common handle (eliminating the power sharing features I will need). All you would need would be 3 differentials; the first for the front axle, the second for the rear axle, and the third for the steering system. This would be pretty cool, 2 people pumping and a 3rd steeting (or maybe the steering is mounted at the center of the pumping post, so 1 person can half-pump and steer)

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Dec 21, 2005 8:59 pm

http://www.geocities.com/wspjafe/DDSS/index.html

I am sick of trying to get this to work - for some I can't get posting images to work today.... IF you go to this link, I have a diagram of how I think the DDSS steering/drive system might work...

Tiahaar · Post by **Tiahaar** » Wed Dec 21, 2005 9:20 pm

dragonfly Jafe wrote:http://www.geocities.com/wspjafe/DDSS/index.html

I am sick of trying to get this to work - for some I can't get posting images to work today.... IF you go to this link, I have a diagram of how I think the DDSS steering/drive system might work...

Duh very sorry! Here's Jafe's excellent description that I missed when tying in the photo...below that is my interpretation.

Jafe: "Differentials apparently sum the torque about the common axis of rotation; the "innards" spin however is needed to allow this to happen.

Green = Differential (D1=Steering, D2=Drive, D3=Right, D4=Left (note: D3 & D4 may not be needed)

Red = Free Hub from 10-speed bike (allows back pedaling w/o transfer of force)

The transmission (marked 3-2-1-R above) determines forward or backward motion

Two or One persons may pedal (if the 2nd person does not pedal, there pedals remain stationary) and each has their own 10-speed selector and hand-brake.

The Collective Axle has the brake ??? (or maybe the actual wheels)

When the steering crank is turned, the D1 output goes to the Right and Left Drive Sprockets (one of these chains only is twisted 180 degrees out-of-phase resulting in opposite rotations). This torque is added to the Right and Left axels (and sums in either D3 and D4 or in D2 if D3 and D4 are not needed). The torque is thus added to on side and subtracted from the other, resulting in a different speed of motion from one side to the other, thus a turn.

If the main drive is not turning (no one pedaling) and the Steering Crank is turned, the two main drive sprockets turn in opposite directions (the torque summing in either D3 & D4 or in D2 if D3 and D4 are not needed), and the vehicle slowly twists in place like a top within it's own length…"

Tiahaar's crap:

As I interpret Bob's system via Elliot's description the D3 differentials you have in the drawing are not needed (in fact would cause either the tank to sit still while the drive pedals spun the steering pedals or a drive lock condition depending on phasing...that will be $400 please heheh), being replaced by a solid shaft on each side that turns the drive sprocket. But the rest of the drawing is brilliant! Shows the way the chains are reversed on the steering D1 outputs (which are always in motion if the main axles are in motion). Very cool and helped me TONS to get a clearer visual image.

PS: 2 drive scenarios for others looking at this, Jafe's got it! (with solid shafts in place of the D3s)

Straight motion: main pedals turn D2, its two outputs both turn the same way, both drive sprockets turn the same way but the chains going to the steering D1 turn one of its "outputs" cw, the other ccw and the steering pedals stay still (or are held still to make/keep the vehicle going straight)

Its like when you jack up both drive wheels on a car and spin one by hand the diff will spin the other wheel in the other direction while the input shaft from the (nonrunning) engine doesn't turn.

Turn in place: the main pedals are held still and someone cranks the steering pedals (and on a skid steer tank this could take some effort/low geering). Both D1 outputs turn the same way but since the chains run one side reverse one main drive sprocket turns cw the other ccw. The D2 diff thus has its output shafts turned in opposite directions (no effect) but one side of the tank is driven forward, one side reverse. Very very clever

I bow down in reverence!

Thus in theory you could be going straight, have someone start cranking on the steering pedals and therefore force one set of the tracks to go faster than the other and wala a turn. I'm thinking way way low gearing for a tank on the steering pedals? I think I will stay with braking the diff output on one side for turning my one-person fast reconn vehicle.

enough for now!

dragonfly Jafe · Post by **dragonfly Jafe** » Thu Dec 22, 2005 9:51 am

I got reply back from Bob Durst, the Kinetic Racer who created the "Killer Tomato" bike and the DDSS system...

Bob confirms what Tiahaar says about D3 and D4 not being needed (I was pretty sure they weren't, but had already drawn them - after a while your head starts spinning along with all of the gears...) He also fears that the force required to make it go might be great. He mentioned that for his creation the standard bike chains are at their limit strength-wise, especially in mud or sand, perhaps I would need stronger chains.

Bob also brings up another facet, you cannot crank the wheel fast enough to get a high rate of turn, which means your turning arc gets bigger with speed. For a tall narrow two wheel bike this is actually good, as it helps prevent you from tipping sideways in a turn...I don't think it will be an issue with my tank, however (high speed and this tank are not synonymous terms).

Lastly, there are Kinetic Sculpture Races starting in May for anyone that wants to see some off these amazing creations in action...

Elliot · Post by **Elliot** » Fri Jan 06, 2006 8:38 pm

Wow, you folks have been making progress while I have been on the road!

I'll catch up better in a day or two, but for now I can mention, in response to the grease/oil inquiry, that I use thin synthetic motor oil (5w20 or thereabouts) in the BMW motorcycle transmissions on "Henry Ford Goes Surfing".

Elliot · Post by **Elliot** » Sun Jan 08, 2006 7:04 pm

Yep, looks like you have it well covered.

I studied the drawing and associated text only briefly -- too much head-spinning for me also! I mostly just close my eyes and visualize this stuff -- or, if I'm actually working on it, I stare at The Machine and visualize the parts that need to be there. Sorry, but that's the only way I can do it!

The question of chain sizes came up.

To my mind, bicycle chain falls into three categories:
1: Derailer (all right, all right... le derailieur, silly vozzy please.)
2: Single speed (and in-hub gears like Mom's Sturmey Archer 3-speed)
3: Various heavy duty versions of single speed chain, used mostly in BMX.

Then there are the industrial sizes. You saw some info on these on the radio-controlled tank web page. These sizes are identified by numbers: 35, 40, 41, 50, 60 and good-grief-you-don't-need-anything-this-big.
35 is bigger than bicycle. 40 is next, and it is the most commonly available. 41 is -- weirdly -- a tad smaller than 40 (same pitch, but narrower -- I would have called it 39, but what do I know!). 50 has been used to transmit the power of a Chevy V8 ("Michigan Madman" E. J. Potter's drag-motorcycle, if memory serves.)
I use #40 a lot. It is the size used on many small and mid-size motorcycles. Such chain, and matching sprockets, can be bought at farm equipment stores in any rural area. In cities, go to industrial power transmission stores. 35 is probably plenty strong for our purpose, but your local Ranch and Farm store may not have it in stock.

One more thing. Around Noon today, I think I finally made the decision to attend my first Burning Man this year. How could I not, right?!

Tiahaar · Post by **Tiahaar** » Sun Jan 08, 2006 10:10 pm

Elliot wrote: Around Noon today, I think I finally made the decision to attend my first Burning Man this year. How could I not, right?!

Super! (it took you this many days???) Hope to see one of your creations out there.

Let's see if I can borrow a piece of chain info from a go-cart site:

Standard Roller Chain Specifications:

Chain Size...Pitch...Roller Diameter...Roller Width...Pin Diameter
#35.............3/8"...3/16"..................3/16".............1/8"
#40.............1/2"...5/16"..................5/16".............5/32"
#41.............1/2"...5/16"..................1/4"...............1/8"
#420...........1/2"...5/16"..................1/4"...............5/32"

#35,40,41 & 420 chain are used in the Fun Kart and Mini Bike Industry
An 11 or 12 tooth clutch sprocket usually indicates the use of #35 chain
10 tooth clutch sprockets usually indicate the use of #40, 41 or 420 chain

OK, sorta worked...only got text...I use BMX chain to connect the pedal cranks and then #35 chain for the miterbox and transaxle. Lots of go-cart websites to get sprockets and chainwheels from.

robotland · Post by **robotland** » Mon Jan 09, 2006 5:04 am

I'm starting to think that I need to add a Tech Swap to the Parade of Domes event....Drive/ride/walk/roll/slither up in your newest creation, and then we discuss, compare, contrast....Then (after sufficient libations are consumed, naturally) we tour the domes....

Lassen Forge · Post by **Lassen Forge** » Mon Jan 09, 2006 9:23 am

Add to this, most motorcycles use 530 chain... 520 for lighter bikes, 630 for heavier or really scary beefy bikes.

They also make "o-ring" chains, which have o-rins between the side links and pin links. Will help keep the dust and grit out, will hold lube better, but create more drag.

bb

Elliot · Post by **Elliot** » Mon Jan 09, 2006 10:37 am

Thanks, Tiahaar and Sue -- yep, there are a lot of chains out there.

I might mention that BMX chain now comes in mondo heavy duty 3/16 wide versions, versus normal 1/8 varieties. But my local bicycle shop tells me this market is so fashion-concious that products come and go a lot.

Now for crank sets. Do NOT use the old three piece crank sets where the arms are locked in place with a tapered pin with a nut on the end. These are weak. The one piece cranks are much stronger. Schwinn with diamond shaped cross section is best quality. Newer three piece Mountain Bike crank sets are no doubt OK -- just not the old ones with the tapered pin.

We "taco" (as a verb) chain rings once in a while. Use beefy ones, or double them up. Two bicycle chain rings can be sandwiched to use a 40 or 41 chain -- same pitch. I haven't done it , but I see it all the time.

Bob · Post by **Bob** » Mon Jan 09, 2006 12:13 pm

NSU motorcycle halftrack specs:
http://www.autogallery.org.ru/m/hk101.htm

Opel 1.5 liter 4-cyl engine, fwiw

Elliot · Post by **Elliot** » Mon Jan 09, 2006 12:43 pm

Yea, but...

Tiahaar · Post by **Tiahaar** » Mon Jan 09, 2006 9:29 pm

Elliot wrote:Now for crank sets...

First, I WANT ONE OF THOSE MOTORCYCLE HALFTRACKS Yow!

Second, thanks Elliot for mentioning bicycle cranks, boy did I even as a bike nut find I knew not so much. I wanted to use "beach cruiser" style one speed gear on my trike, found the bearing sets and one-piece cranks easily enough but finally had to make the bottom bracket shell to put it in. Next, after running the trike with toe straps for a year I wanted to upgrade to clipless pedals and found no-one makes clipless pedals with the 1/2" thread, and the end of the crank doesn't have enough size to drill and re-tap to 9/16", AND no-one makes a one-piece crank with 9/16" pedal threads grrrrrrrr. There are little screw-in adapters but they move the pedals wider and looked like a good place for a break to happen.

The good news is that BMX bike parts companies do have three piece cranks that fit into the pressed-bearing-cup (American style) bottom bracket with the magical 9/16" pedal threads. The bad news is that they are expensive, though budget "Poverty" 3-pce cranks can be had for @$30...the next step up is around $50-60. yeeps.

'Course if you're using whole bikes to start a pedal-powered project you're already ahead of all that stuff. I just got my new cranks a few weeks ago and need to get out and put them on. Hope they fit.

Steven bradford · Post by **Steven bradford** » Mon Jan 09, 2006 11:53 pm

Damn, What with these great posts that I only understand 10 percent of, if that, motorcycle half tracks, and Tiahaar's sexy avatar pic, this thread is making me way too hot-- and homesick for the playa.

Lassen Forge · Post by **Lassen Forge** » Tue Jan 10, 2006 12:11 am

Bob wrote:

Opel 1.5 liter 4-cyl engine, fwiw

I have my eye on one of those... I hear they leave something to be desired for handling, but otherwise... yeah... found one. (Actually, I know of 3, maybe 4, but the rest are in Eurpoe)...

If we can swing a deal on it... it's fire engine red (ikes), but if the$$$ comes thru before brc, it'll go OD + camo real quick...

bb

Elliot · Post by **Elliot** » Tue Jan 10, 2006 7:17 am

.

Hi Sue:

""" ...they leave something to be desired for handling..."""

You THINK!?!?!

Now we know why they lost. (And good thing too -- my father fought in the Norwegian Resistance.)
...said the guy who has four BMW motorcycle transmissions in that thing in his avatar.

KettenKraftrad must be Kraut for "Pig On Roller Skates"! Or look up "Tits On A Fish" and you will probably find a photo of that motorcycle wheel that has no business being there.

Oh, and yes, now that I know I am finally actually going to BM, I don't know how long I can make myself stay out of the Apokiliptika vs. Herring fray!

Lassen Forge · Post by **Lassen Forge** » Tue Jan 10, 2006 9:45 am

Tits on a fish?? As I understand it from te Herring Crowd, , fish are afraid of tits! >giggles<

When I was a kid, my granddaddy owned a borax (and occasionally gold) mine in west-central Nevada - the first vehicle I was allowed to drive by myself was a D-4 Caterpillar with blocks on the pedals so I could drive it... Actually got quite good at running that thing around, and thought for a while about building an art tank from one until I got turned onto these tractor troikas...

My guess is they figured that front wheel would have acted like a rudder in heavy mud or snow... Having owned and driven a "conventional" VW 3 wheeler for quite a while, and knowing how ineffective the front wheel can be on that, I can't see how the front wheel on the Kettenkrad would have done *anything* other than give the driver something to hold on to...

Then again, for a "track layer" those tracks are really skinny... Hmmm... Prolly pretty easy to re-track one when it decides to detrack itself... n the d-4 you needed a pait of hi-lift jacks, a pair of comealongs, a track pincher, and a lot of luck... >grins<

bb

Elliot · Post by **Elliot** » Tue Jan 10, 2006 4:20 pm

.
Did I miss something -- is the Kettenkraftrad amphibious? Then the wheel could serve as a rudder, yes. We do that in Kinetic Sculpture Racing. Looking at the wheelie-picture on the magazine cover, the KettenKraftRad does seem to have a hull-like structure. But I see no reference to water travel in the specs. Oh well -- there isn't much water on the Playa is there?! As for mud, I think we covered that in the other magazine cover above!

(For those whose parents were not in Mil-Org, Oslo, under the Occupation:
Kraft = power, strength, motor.
Rad = wheel, bicycle.
Ketten I think is safe to assume means belt, track.

Lassen Forge · Post by **Lassen Forge** » Tue Jan 10, 2006 4:49 pm

Elliot wrote:.
Did I miss something -- is the Kettenkraftrad amphibious? Then the wheel could serve as a rudder, yes. We do that in Kinetic Sculpture Racing. Looking at the wheelie-picture on the magazine cover, the KettenKraftRad does seem to have a hull-like structure. But I see no reference to water travel in the specs. Oh well -- there isn't much water on the Playa is there?! As for mud, I think we covered that in the other magazine cover above! :lol:

(For those whose parents were not in Mil-Org, Oslo, under the Occupation:
Kraft = power, strength, motor.
Rad = wheel, bicycle.
Ketten I think is safe to assume means belt, track.

I think Ketten is Crawler.

I don't think they're amphib (and no, I won't be taking one into the lake to find out >giggles<) - what I meant was the front wheel would sink into a loose surface like mud or snow and pull the front end in the direction the wheel is facing. It'd have to hhave some oretty heavy-duty spokes due to all the sideloading if this was the case.

IF this one comes thru, it's gonna be a lot of fun. I wonder how fast they are - I would think on one hand, not very, but on the other, with skinny tracks it might just hum along.

Of course, I'll have to fab a set of highway blocks for it, or get a second track and make smoothies out of them... >grins<

bb

dragonfly Jafe · Post by **dragonfly Jafe** » Tue Jan 10, 2006 5:00 pm

...historically they were used to tow light artillery/anti-tank guns, I have never seen one travelling faster than 15mph or so, most are going slower than that...just because it CAN go faster doesn't mean you WANT to!

Elliot · Post by **Elliot** » Tue Jan 10, 2006 5:02 pm

(edit) Ah -- Jafe snuck in between us! I don't type fast enough!

B.B.Sue:
Right.
The front wheel appears to be a steel disk, so that would work to some degree.

But the tracks would need to be marching to the same drum, I should think. We have had plenty of Kinetic Racers discover, right after the race started, that they could not turn their trike without a diff -- somewhat like your experience with your Kraft (durch Freude) Trike, apparently!

Elliot · Post by **Elliot** » Tue Jan 10, 2006 6:15 pm

.
Jafe:

Thanks to Bob introducing this Mechanized Mutt to the discussion, I think we are ready to give your Pedal Tank a name. How about Ketten Kraft Krawler. Hmmm...scary initials. Ketten Kraft Mutt? No, we need something "pedal" or "foot" instead of Kraft. What's a Kraut word that starts with K or M and relates to pedal power? Or just KettenKrawler.

This thread is drifting, isn't it!

Bob · Post by **Bob** » Tue Jan 10, 2006 10:15 pm

Polish cavalry, c.1930

http://derela.republika.pl/wz28.htm

Tiahaar · Post by **Tiahaar** » Tue Jan 10, 2006 10:33 pm

Elliot wrote:This thread is drifting, isn't it!

(De-tracked? heehee) I used to work on a ranch up in Idaho summers/winters during college breaks. One winter job was pulling bundles of logs down to a sawmill with the "cutest" but very serious pulling mini cat (real model??), not much bigger than the cycle halftrack (and what is that Polish thing I see snuck in as I was typing??). I managed to de-track one side one day. MAJOR pain in the butt getting it put back (Sue! you can relate!). That's a younger me only smiling for the camera...

Elliot · Post by **Elliot** » Tue Jan 10, 2006 11:22 pm

.
The Polish thingie has a much longer wheel base, which gives the front wheels weight and leverage to work normally. The problem with the Katzenjammerrad

is that the wheel is almost between the tracks where it is just along for the ride.

At the Towe Automobile Museum in Sacramento, CA, we have a Ford Model T that was converted to a halftrack, plus skis on the front wheels. Such conversions were not uncommon in the old days.

I cannot seem to link it, but you may be able to click, or cut and paste.
http://www.toweautomuseum.org/html/towe_475_20.html