[summary]The LifeTrac Protoype II is an open source tractor that can be easily assembled in 6 days.[/summary]
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== Design Rationale ==
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== The LifeTrac Story ==
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Basic discussion of design rationale is [http://blog.opensourceecology.org/2010/07/open-source-tractor-update/].
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[image|20208]
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'''Definition''': LifeTrac is a low-cost, multipurpose open source tractor. LifeTrac is a versatile, 4-wheel drive, full-sized, hydraulically-driven, skid-steering tractor of 18-75 hp with optional steel tracks. LifeTrac is intended to be a minimalist but high-performance, lifetime design, design-for-disassembly workhorse and power unit of any land stewardship operation. It features featuring easy serviceability by the user. Its modular nature allows for quick attachment of implements; interchangeability/stackability of multiple power units (Power Cubes) for adopting power level to the task at hand; quick attachment of all hydraulic components via quick-coupling hoses; including quick interchangeability of hydraulic motors for use in other applications. It can be fitted with up to two sets of loader arms. LifeTrac is intended to be used with modern steam engine Power Cube module for fuel flexibility, such that locally-harvested, pelletized biomass crop,such as hay, may be used for fuel. Regarding safety features, LifeTrac replaced the traditional power take-off(PTO) shaft for driving other implements with a detachable hydraulic motor for the same purpose, where this motor may be mounted on the tractor, on the implement, or wherever it is required.
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This insane freak purrs like a cat and rips the ground. Major success.We have now demonstrated a workable design with LifeTrac II. Can it be any simpler? We took out the articulated joint that was present in LifeTrac I, since OSE Specifications prioritize simplicity. Skid steering may not be as elegant as articulated steering, but it works just as well. Moreover, a fixed wheel base allows us to mount tracks on the wheels, such that the obtainable traction surpasses that possible with LifeTrac I – which cannot accomodate tracks because of its articulated joint.
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'''Problem Statement''' – Industrial tractors are being designed increasingly for planned obsolescence with 10 year lifespans,and the user typically cannot service their own tractor due to complexity of design. Power transmission and engine systems are the dominant failure modes of tractors. Fuel costs are a significant expense of operating a tractor. Capital costs of purchasing tractors typically place their users in debt.
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The frame is bolted together from 1/4″x4″x4″ mild steel square tubing. A hydraulic motor is mounted on each wheel. Quick-connect hoses run from each motor to the control valve. The PowerCube connects to the control valve with two additional quick-connect hoses.
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'''Solution''' – LifeTrac is designed to be the peoples'tractor. The user is able to service, modify, and produce fuel for the tractor. Gear transmission is replaced with a hydraulic drive train, where quick-connect, flexible hoses are the means of transferring power. Lifetime design (bolt-together construction, modularity) with general purpose parts allows the tractor to be passed down from generation to generation, before its life-cycle is completed as feedstock for the induction furnace. The absolute simplest design facilitates creation of small-scale enterprise for manufacturing these tractors in as little as 3 days of time using a RepLab1 facility. This allows communities to be entirely self-sufficient in their mechanical power infrastructures, while reducing lifetime costs of tractors by a factor of at least 10.
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The flexibility of the design is extraordinary – wheel motors are detachable and have quick couplers. The valve is detachable and has quick couplers. The hoses have quick couplers. This means that all these hydraulic components may be used elsewhere, as part of a flexible Lego set for real technology. Moreover, the quick disconnects allow this tractor to operate in 2 wheel drive and 4 wheel drive.
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'''Development Status and Needs''' – We have completed Prototype I-III, and we are currently on Prototype IV. Prototype I (ref) was an articulated version of the tractor without roll cage,and Prototype II (ref) was an enclosed version with tracks and skid steering. Prototype II has demonstrated quick-attachment and stackability of power units (ref), as well as interchangeability of wheel motors and control valves via quick-couplers for repurposing in other applications. Prototype III was a shortened version of Prototype II with only one set f loader arms, and it featured CNC Torch Table assist in its fabrication. Prototype IV (Current as of Dec. 2011) introduces [[Quick Connect Wheels]]. Moreover, minor redesign (thicker wheel shafts and bearings (2.5" instaed of 1-7/8") of LifeTrac lend themselves to adaptation as a tracked bulldozer – via addition of chain gear reduction to the direct-coupled wheel drive.
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We know of no other machine in this world which features this level of part interchangeability or modularity. This is a feature that allows one to control equipment costs to the lowest possible – not only by repurposing components, but being able to service or repair the machine readily.
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LifeTrac satisfies many of the [http://opensourceecology.org/wiki/OSE_Specifications#GVCS_Specifications.2FCore_Values]
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It turns out that 18 horsepower – or a single PowerCube unit – is quite satisfactory for driving this basic tractor. The next step is to build tracks to connect the wheel pair on each side, such that traction is never lost on uneven terrain.
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1. '''Open Source.''' The LifeTrac was designed from the ground up with the intention of making freely available not only the design,but also the education necessary to understand, use, and improve the design.
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If you would like to build the above tractor, the Blender drawings of 23rd of August, 2010, are exactly what we built as far as the frame above. We may shorten the wheel base if we have problems with skid steering – so this is a consideration for any early adopters out there.
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2. '''Low Cost.''' As compared to its commercial equivalent, the LifeTrac is 1/5 ofthe cost to acquire. There are even more dramatic reductions in the cost to own.
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== Test Drive Video ==
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3. '''Do-It-Yourself.''' Most of the components and sub-assemblies are held together with bolts. If you've got a wrench you've got a tractor.
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[video|http://vimeo.com/14376927]
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4. '''Closed-Loop Manufacturing.''' Because the materials the LifeTrac is made out of require so little machining, they can be produced by future GVCS machines. No need for exotic materials or fancy injection molding.
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== Build a LifeTrac ==
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5. '''Industrial Efficiency.''' The LifeTrac's performance is designed to be comparable to industry standards, and we are approaching that point quickly.
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[image|20207]
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6. '''Lifetime Design.''' Unlike what is available commercially, the LifeTrac is designed to function indefinitely. Design for obsolescence is avoided, as maximum service to the user is part of the design.
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7. '''Robustness.''' It ugly, but it work.
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8. '''Technological Recursion.''' LifeTrac is part of technological recursion at the deepest level, in that it is responsible in part for extracting raw resources from which all things are made.
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9. '''Local Resources.''' What good are the resources under your feet if you can't use them? The LifeTrac opens up new avenues for self-sourcing.
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10. '''Replicability.''' With full documentation of how to source the materials, build the tractor, and use it in the field, the LifeTrac eradicates barriers to entry.
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Interested in the idea of building your own? Or, have a real need for a modular tractor designed for a long, useful life? Then consider building your own with this [[Build_A_LifeTrac|Build A LifeTrac Guide]].
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