MicroTrac Challenge

We have recently shown the initial test drive of LifeTrac Prototype II. The 3D model in Blender corresponds exactly to the machine built – the point being that the models in Blender are useful as actual design drawings from which others can replicate a build. The design may be scaled – meaning that the same components may be used on a machine of a different size. This implies that a MicroTrac may be based on the same design. See our previous work on MicroTrac – which is based on one driving wheel.

We are proposing MicroTrac Prototype II to be a small version of LifeTrac, as opposed to the one-wheel drive version. Stability and traction issues need to be resolved on the one-wheel design, so a good solution may be to do another simple box with wheels, like LifeTrac Prototype II. If we use the same or similar components, that means that parts will be interchangeable between the two machines – consistent with our principles of radical modularity.

This is our MicroTrac Challenge – for you to design the best, smallest implementation for MicroTrac Prototype II, built around the components of LifeTrac Prototype II. If you have no skill or experience in building a working tractor, this could be your start in your career as a design-builder of open source tractors. We have a design that works – and it may be modified easily – so our Blender drawing may constitute an Open Source Tractor Construction Set. It may even be used to build larger machines, in which case 3/8″x4″x4″ steel tubing may be used instead of 1/4″ wall tubing, or tubing larger than 4″ may be used.

Who is up for the challenge? The Blender drawings are downloadable. So download them, play with them, and create a small version of LifeTrac. We will build (in real life) the smallest successful design – which should be around 4×4 feet in floor area – or smaller if possible. If someone comes up with a successful design – we’ll be one step towards funding and building it – and it’s a great opportunity for remote collaboration.

Here are some design considerations and explanations of LifeTrac II for those interested in proposing a design for the MicroTrac. As a starting point – simply take the LifeTrac II design – shorten the frame members and loaders, and there you go. You will run into issues of how to narrow the wheel base while using the same wheel mounting strategy as we used.

See the Appropedia description of LifeTrac II as a start. The design features radical design-for-disassembly and modularity. Wheel motors, hoses, valves, and power units are modules that can be connected and disconnected readily for use in other applications or for service. The frame bolts together.

  • One hydraulic motor drives each wheel in LifeTrac. The same could apply to MicroTrac. Microtrac may do well with 2 wheel motors.
  • Motors are coupled via 6-spline, 1-3/8″ PTO type spline couplers for ready disconnectability.
  • Frame is 1/4″x4″x4″ square tubing.
  • Skid steering is used. Tracks will be added to LifeTrac for added traction. Same principles apply to MicroTrac.
  • 3 PowerCubes may be mounted on LifeTrac. For MictroTrac, one 18 hp power cube will be ample power.
  • 2 loaders will be used on LifeTrac II. MicroTrac could do with one.
  • 4-wheel or 3-wheel configurations will work for MicroTrac.
  • To narrow down the wheel base, hydrauilic moters may be staggered, such that the wheels are staggered slightly.
  • Smaller wheels other than 16″ truck tires may be used in Microtrac.
  • Wheel chains may be desirable on MicroTrac for added traction.
  • Plates are bolted to the frame to mount bearings and motors.

What else could we say? Please ask questions if you have any, and let’s make MicroTrac a collaborative design challenge. Please pass this on to the likes of Engineers Without Borders, Science for Humanity, organic farmers, sustainable builders, and other supporters of the resilience movement. The vision is to produce an open source equivalent comparable to, though larger, more flexible, and more powerful than, the BCS Tiller.


  1. Abe

    So, when are we going to be able to purchase a LifeTrac or MicroTrac kit? I need one with tracks that could server as a bulldozer!

    Good work on these projects!

  2. James


    I’ve been following your work for about a year: Great Stuff! Also enjoyed your interview on podcast. (I listened to it while on the tractor, if that earns bonus points)

    Anyway, I thought I’d take a stab at the MicroTrac II design. Since I had to learn it for a class I’m teaching, I did the design in Google Sketch-Up… but am unable to upload to the google library. Can I send you the files directly? Is there an email address I can use?

    Design highlights:
    4 wheels, skid-steer w/ tracks and 2 hydraulic motors. Operator stands/sits on platform in center, power cube attaches on one end, loader arms on the other end. Attach a loader bucket and use the tractor in “forward” mode. Attach a rototiller/etc to the quick attach plate, and use the tractor in “reverse” mode good operator visibility for forward and reverse travel.
    Footprint is about 4’x4′, but the power cube hangs over the back, and the loader hangs over the front making it about 4’x7′.

    my design inspiration came from the bobcat mini track loaders ( ), but swap the positions of the engine and the operator.

    Is this similar to what you are looking for?


    1. Marcin

      James’ design contribution may be downloaded at

  3. Marcin

    Hi James,

    If you have a file to share, we can put it up on OpenPario – our design repository. Please sign up there:

    can you send me a jpg in the meantime? We can put that on the wiki and embed it in the blog. We’re working on a 3D display function for the blog and wiki – so casual viewers can view and rotate the image themselves.



    In a skid-steer design with 1 motor on each rear wheel, are you thinking of putting on tracks like LIfe Trac II and letting the tracks go around the front wheel too? Easily removable/replaceable tracks would give more flexibility: tracks for softer ground vs/ trackless for less damage to a lawn (perhaps in the trackless mode the front wheels could be free to swivel left or right or even be steerable).

  5. […] That is one of the realities that we believe are forthcoming in the near future – after MicroTrac and our steam engine are deployed. Share […]

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    […] Links: completed, zero turn, wiki documentation, Prototype II Wiki, Prototype II Challenge. […]

  7. MaruAdvneturer

    Well, for a smaller version, you might look no further than a ‘Dingo’ that are produced in Oz. Its a commercial development. link — But this configuration would make an excellent starting point for a FOSH development.

    As I might envision it you would drop a power cube in the belly to act as ballast and power. Some of the parts sourcing I might suggest comes from a gutted quadtrac ATV for tires, driveline, controls, etc.

  8. […] That is one of the realities that we believe are forthcoming in the near future – after MicroTrac and our steam engine are […]

  9. Jesse greenwood

    A slight twist on this would be seeing it as a self propelled power cube with seat and loader bucket. Instead of modular/dismantlable, make it as consist and self contained as possible, with all the parts sorceable at your local tractor supply store (I am in Canada, so I would say princess auto)
    Basicly like any of the 36″ wide under 3000lb skidsteers. The older ones can basicly be serviced by anyone and get replacement parts genericly anywhere.
    This may not exactly fit your vision, with bolt together frame and removable power unit, but it could be more than just a smaller version of the lifetrac. It should try to be its own thing. Just my 2c

    1. Marcin

      Good comment, it we are migrating somewhat in your direction by welding where appropriate to make the machine more tight.