Marcin based the original design on CADTrac: http://www.cadplans.com/cadtrac.htm

Our initial engine plans were to make removable hydraulic power units with diesel engines, but we couldn't find a reliable source for diesels. So we are going with a gas engine from a ride on lawnmower for the first hydraulic "power cube" which Marcin is working on now. Check out the MicroTrac page for our initial designs and sourcing: http://openfarmtech.org/index.php?title=MicroTrac

Eventually we hope to be able to build and use modern steam engines for the power cubes which will be able to use local pyrolysis fuels.

Have you considered allowing for even full size car/light truck gas engines and diesels?  I posted another thread with a design i've been brainstorming on for years but i'll repeat a few advantages here:

   - Often available cheaper than an industrial engine, especially used

   - Plenty of power

   - Understressed since you'll only be using 1/4 or less for a gas and 1/3 to 1/2 for a diesel typically of the power rating (and I wouldn't recommend using more than 1/2 the rated power anyway since car/truck engines dont expect a 100% sustained power load)

   - Extra weight not necessarily a detriment (many tractors add weight anyway, 3000lbs for the whole thing seems a little light to me vs a skid steer or utility tractor)

   - If you choose certain brands of engine, the exact same mounts/bellhousing would bolt up to a variety of gas and sometimes diesel engines.  

   - Two inexpensive diesel engines to consider would be the GM 6.2 (typically 150hp) and Oldsmobile 5.7/350 Diesel, which if later were not working and you had to harvest or something could be easily replaced by gas engines in an easy bolt up.  The latter has a bad rep that is fixable cheaply. (see my other post)  Being they are 20+ years old and not really manufactured anymore they are not on every corner, but they are not hard to find and not very expensive when found, rebuilds of the 6.2 are still available online for less than any other rebuilt car diesel i've heard of (often around $2200 last I checked).  The newer 6.5, 6.5 turbodiesel and Duramax 6600 would work as well with the same bolt patterns and are still manufactured, but will cost way more than a 6.2/5.7. (yet STILL less new than the new55hp Perkins at $7000)

Actually on the parts end, the OSE plan is to be able to make from scrap metal all the parts one needs. Obviously that isn't going to happen any time soon, due to the need for a lot more infrastructure and talent on board, but the idea of being able to manufacture your own hydraulic motors is sound. Until then, its begging and scraping by with surplus/used.

I'm glad to see that people are finding the videos useful. Just out of curiosity, do people find videos or pictures and documentation more useful to replicate this sort of thing?

I like the comments about the motors and power train. In theory we are looking at steam power using pyrolysis oil or pellets from grass/wood fired engines. The idea is that biofuel is rather handy to come by on a farm. This isn't possible on all locations of course. 

For my two cents, what I'm most excited about is housing. I really like the vaulted brick concept, I just wish it wasn't so late in the season which will probably delay housing construction until spring. Apparently freezing temperatures don't make for the best outdoor building conditions. Go figure.

Yep, those are all the juice problems that are coming up!

What I'm interested in and am working towards, is a different concept of fabrication. Basically where the tools and procedure of building are just as important as the end product. Most companies can get away with mass production because they make one kind of widget, but I don't need ten thousand of the same widget. I need lots of different kinds of widgets. This isn't an easy problem and thankfully one that is too expensive for most large corporations to be thinking of. Also, patents aren't like copyright, which is insane. I don't have to wait 70+the life of the author. Its more like 20 years, I believe. 

Basically, look up www.reprap.org and then apply that to metal. The hope is to turn manufacturing into as easy of a process as writing a computer program, which is its own kind of difficult, but in some ways easier.  I've already got some ideas on how to make all sorts of things like electric motors, metal parts, etc. What I'm working on is the general platform to build it all on.

The hard part is this pulling yourself up by the bootstraps bit, means you've got to have some beefy arms, and a lot of knowledge of leverage and physical mechanics. 

I don't get on much, following up for first time since I posted originally.  :-/  Responding to Allen15 first since thats a long one:

To ganging power steering - I guess my question is what kind of pressures and gph volume flow is needed to run the hydraulics?  A random guess for a light pickup pump is probably like 600-700psi from the factory and likely capable of putting out 1000-1200psi, at something like 1.6gph (not alot, but if the alternative is nothing its better than nothing, slow but working may be better than not working).  I think I saw those figures somewhere.  A semi pump should put out a fair bit more. Ganging a few together shouldn't be too hard, any more than when the car stereo guys build a custom box with like 4 alternators on it because theyre pushing kilowatts.  But then i'm not a hydraulics expert, thats just my scrapyard challenge mind.  My interest in supporting the possibility of that would be for true junkyard engineering and third world use, maybe you cant afford a replacement proper hydraulic pump but you have a few car and pickup pumps you can quickly slap together to the tractor to still make harvest or to finish the only important job before winter so you can put off a proper repair due to unavailable funds.  All it likely requires is enough room for a shaft drive off the front of the engine (i'm guessing) and enough room for such improvised "whatever is available" pumping systems you can put together. (this also becomes a front PTO of sorts)

Nearly any engine can run on sustainable fuels.  Gasoline engines run on alcohol and producer gas/wood gas/biomethane fairly easily, diesels run on plant oils.  Alcohol is often confused with just corn ethanol which is a terrible way to make alky, there are far more productive methods for alcohol per acre or using waste feedstocks from say a juice or candy factory where available.  I guess I like the idea of supporting "nearly any engine" to avoid the exact problem of becoming dependant on something that is a market surplus now which dries up later. (the Saturn wiper example)  If you can use nearly any domestic inline 4, V6 or V8 gas or diesel small or big block you're pretty much set.  The market can change in 30 years but you'll still always have engines available.

For junkyard semis it all depends on the use they are put to.  I guess the point is that if you are scaling up to a 400hp tractor or dozer, even if you buy a used semi it's going to be way less than a 6 digit full sized tractor doing the commercial farming or construction job.  Or something you could scale up to the size of a commercial backhoe if you were ambitious, with decent skid steers costing $12,000 and up used for a small one you could probably build a fairly bigger one for the same cost with less risk of stuff breaking expensively.  I just think it would be cool to have the option.  For instance school busses are often available for $2000 if you know where to look with a medium duty diesel and Allison and still have a fair bit of life left in them because of safety regulations requiring new busses before they are totally worn out.  If I lucked upon a cheap semi i'd use that instead, i've seen a few due to the market right now.  It doesn't have to last another million miles, just sometimes you need a larger machine to do a job quicker even if the total hours you ultimately can put on it before a rebuild or another engine swap aren't that excessively much.  Maybe i'd do like they did in vietnam in the 70's and 80's and swap the vehicle engine into the tractor for harvest, then swap it back into the vehicle or lorry when harvest is over.  :)

If one wants a used semi diesel should probably be rebuildable multiple times, thats why they have sleeved blocks and such.  But for the cost of $8000-12000 for an overhaul I probably wouldn't.  Rather i'd look for one of those anomalies, someone that maybe rebuilt it 400,000 miles ago then stopped trucking or whatever.  Something that would still have a few thousand hours left of good work on it.  I routinely hear of school bus buyers putting another 100,000-200,000 on their busses with less long life intended medium diesels which already have 150-200k on them without major work if they start with a good diesel like a Cummins 8.3 ISC - thats 1500-3000 hours at 65mph and is rated 260 to 310hp in urban bus use. (up to 400hp for more intermittent duty like a firetruck but the lower hp will last longer)

Let me suggest the powertrains that are good values like this, if someone else can help me figure out the hydraulics and implements and how things scale up.  :)  I just ask if possible that if I refine this idea further with the help of others that maybe implements and hydraulic systems could be helped to work with it as well as the Lifetrac, since i'm trying to cover every variant of drive and powertrain i've seen.

I know I havent covered running the implements yet, thats why i'm seeking co-engineering.  :)  As to bolted together improvised stuff - 1930's doodlebug tractors were often driven to highway speeds because the front half was basically just an existing car, like a Model A ford.  The rear half was just a second transmission, truck axle and some brake mods for separate left/right braking for tighter steering and to stop one tire from spinning in mud and such.  I wouldn't suggest running articulated or skid steer tractors at highway speeds, only something in the style of a classic doodlebug using conventional steering if still mostly the vehicle it came from and was still legally roadworthy as that vehicle.  Backhalfing a hot rod (for monster tires and drag suspension) doesnt legally make it a custom built vehicle if it's behind the passenger compartment AFAIK.  Safety shouldn't really be affected.  Again I was hoping for a design that would be largely compatible through several different designs - conventional front engine/RWD or 4WD designs, articulated centers (like the LifeTrac), skid steer/tracked designs (separate left/right power) but otherwise the dream is for the exact same implements to work on any of them and share engineering.  (has anyone ever seen any other drive method besides those?)

Anyway my guess is that running some kind of snout off the front off the engine should give a PTO shaft, I don't know why it shouldn't work anyways. All it should require is allowing for ample room off the front of the engine but before the radiator (such as the ability to use long front loader arms for instance) so you can do whatever you need to with that power shaft like running a bunch of V-belted stuff.  And letting the vehicle be long enough for dual transmissions while still taking the center of weight into effect (for things like a front loader needing longer arms to balance right).  Perhaps the cost of hydraulics is less on the LifeTrac since it's just the fluke of that size has a surplus pump available, it may not apply on a larger backhoe-sized or semi engined vehicle.  I don't know if power steering pumps is "the answer" til I try it.  A used schoolbus with Cummins and Allison might well be cheaper than trying to make something for that size to have hydraulic drive wheels.  Save the $ for just the PTO shaft system in that case.

A trailer for a LifeTrac isn't too expensive but one the size of a normal semi-pulled backhoe I assumed wont be cheap.  If I can use a doodlebug style and just drive it there (by basically back-halfing the chassis of a schoolbus front) that may be the right answer for me.  Another person may absolutely need the tight turning and may have a flatbed so will go with the articulated tractor.  Another may want tracked drive (maybe they want a dozer for mud and need lower ground pressure) or skid steer design with separate left/right power using some different design like a pair of engines and transmissions even.  

Not saying anyone should change their design or feel burdened by my requests, just saying what i'd like to see designed or to work with on the ultimate design for, and why.  :)  I plan to work on the powertrain projects in all the above at some point as I get time, i'd want a universal toolkit so that whatever you want to design, for whatever country you live in and surplus market condition, as much of the design is compatible and shared between different styles as possible.  In america i'd be running an olds diesel, if I were in Africa i'd probably be using a range rover 4.5L V8 because those are common there, in any asian country i'd likely be using honda or isuzu or toyota.  This should primarily be an issue of implement design more than anything, instructions how a third world farmer without a knowledge of engineering could easily modify an existing front loader implement design (or a backhoe) with a different center of balance attachment to the tractor because it's further back for instance.  Youre just allowing for the dimensions to be big and long enough or easily extended without a college degree - mostly about allowing longer nose designs in front of the cab for instance so you can have big engines and dual in line transmissions to get the ratios you want.

Responding to others now:

Allen15 second post: the reason for my "support everything possible" is because of the problem that what is surplus and cheap now definately wont be later, all markets change.  Allowing for the 3 main types of drive I see (articulated, skid-steer/separate left/right tracked drives even including separate engine or eng/trans per side like say some early tank experiments, and conventional front steering axle/front engine/differential drives) and multiple engine sizes/shapes and both shorter or longer vehicle lengths lets you build a cross-compatible knowledgebase of people building what they need for their specific needs.  Maybe my power steering pump idea is a dead end, or maybe someone else can suggest another source of an off the shelf improviseable pump. (maybe airplane hydraulics?  Those run 3000psi and fairly high gph I think.)

I'm just trying to make my own designs more compatible and adaptable to other needs, in return for asking the same in turn.  As far as PTO type drives I guess the options are mechanical, hydraulic, pneumatic, and electrical motor.  Then using either "proper" professional stuff (like hydraulic motors intended for the psi/volume/duty cycle of construction equipment) or improvised/recycled/repurposed stuff as is or with modifications (like turning a semi power steering arm into a hydraulic ram, dunno how much force you'd get for what pressures or what mods to make it exclusively driven by hydraulics without mechanically activating the check valves via turning a steering wheel, but maybe it could work for someone?)  If I could i'd try to create implements that could use any of the four power methods!  Given a shaft drive off the front of the engine and enough room for all the belts and such you want to put on it you should be able to hook up nearly anything for PTO power out though.

I might even use a separate engine for the hydraulic drive in some instances from the powertrain.  Or even more than one engine with separate pressure/volume levels.

(hopefully i'm not repeating myself too much or pedantically, just not sure if i'm clear is explaining why and how I think is all.  Yes i'm trying to convert others to my way of thinking because I see no real downside to the flexibility, but if it's not designed in at the outset it's possible the project could paint into a corner and need notable reengineering to ever support it.)

So what was the hobby group and project that used a Saturn wiper motor?  I'm just curious what used such a specialized thing.  :)

To Lawrence - using scrap mechanical parts is what i'm trying to think of ways to do (by using power steering parts) to match the ability to use scrap steel elsewhere.

To Allen15 3rd post - just to talk fun, there shouldn't be any reason to make an exact clone of a Chevy 350.  Even if the bellhousing patterns or cylender head water passages/bolt holes happened to line up as long as other things were different it shouldn't matter legally AFAIK unless you copy specific patent designs. (ie - the full VTEC valvetrain from a Honda).  They stopped making the old style engines more than 10 years ago and i'd think any patents on the old small block would be expired unless they came after 1989 or so, pretty sure there's been no big patentable improvements to the original design after that.  (be different if you were cloning the LS1 or something) But as to the literal possibility of casting your own engines (an idea I think is cool and worth thinking about if were talking multigenerational sustainability and the possibility of serious social upheavel disrupting markets and availability sometime in the next 40 years) I would take a trip back into the past to simpler to cast designs - think separate blocks and air cooled finned cylenders and heads, each independant so whether you build a 1cyl or a V12 or flat 16 or 42cyl aircraft style they could literally use the exact same cylender, cyl head, piston, perhaps connecting rod, and valvetrain parts compatible between all even if the core block and crankshaft differs.  Maximum parts compatibility would be the goal.  You could make the dimensions compatible with the most common engine ever (the chevy small block) so that cheap, strong, common internal parts could always be obtained and not cast from scratch, since those parts are more demanding (I think) than the metallurgy required for the cylender block for instance since the block isnt a rotating ultra weight-critical part except for the higher power to weight ratios.

Were I to engineer/design something as ambitious as an open source cast it yourself engine I would do some things to make them the equivalent million mile 30 year engines like fully sleeved blocks instead of the throwaway 150k mile/8 year designs of car/light truck/many medium truck designs are intended to.  Or I might take into account other concepts like the slow speed Lister-style diesels - which were designed to run 50,000 hours before a rebuild, and then literally be rebuilt by any grandma with simple hand tools, in the place they stood, without even removing or lifting the engine.  (the connecting rods and piston come out through the top of the engine once the head is off so you can replace the bearings and other wear parts were made for easy home maintenance access)

FWIW I like steam engines too.  :)  Properly designed there's no reason you couldn't support both steam and internal combustion power.  Allow enough physical room for the lower power to weight steam engine and boiler (coincidentally what I was suggesting for other reasons) and it should be possible to use that with this design too.

To the scrap/surplus vs reliable issue, thats another case where different people will need different things, and I see no reason all options couldn't be allowed.  If I can use an Olds Diesel 350 i'm not too worried about reliability - swapping in another engine is within the range of any shadetree mechanic, and having a few spares not too expensive.  Rebuilding the main one I use will cost way less than a perkins diesel or just buying a rebuilt 6.2 GM diesel for $2200 as i've seen.  The engine will be understressed in this app and give plenty of power.  I'd want to spend the extra money I have buying reliability for the hydraulic system, thats what i'm worried about breaking. (though I talk of improvised power steering stuff I wouldn't want it on my primary machine or implements, it's more a backup plan if it later breaks and I dont have the money to fix it perfectly, I fear something breaking when a critical project is 90% done and i'm out of funds.  Better running at 25% speed and half power than not running.  Or i'd use it for low importance/less often used or experimental implements.)

Cool that someone linked reprap - I think it should be possible to create some kind of a jig to cut like a gear tooth hydraulic pump and machine out a casing for the same in a desperate pinch.  It probably wont match the cost and performance of a profesionally made one however.  My concern isn't the cost, just a future of possible market unavailability.  By supporting everything you can almost never be held under siege.

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