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.