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The above considerations result in LifeTrac with the highest degree of simplicity and highest degree of flexibility - even compared to LifeTrac I. Based on our learnings, we believe that we can deliver the world's first, completely life-size Lego Set for heavy equipment. This will allow amateurs and professionals alike to tame machinery into useful service. In particular, the design specifications are:
The above considerations result in LifeTrac with the highest degree of simplicity and highest degree of flexibility - even compared to LifeTrac I. Based on our learnings, we believe that we can deliver the world's first, completely life-size Lego Set for heavy equipment. This will allow amateurs and professionals alike to tame machinery into useful service. In particular, the design specifications are:


*Bolted, xyz construction with 4x4 inch square tubing as the stock steel of choice
*All metal used is stock steel, and requires minor amounts of welding in lieu of bolted, xyz construction
*
*



Revision as of 05:31, 30 December 2009

Introduction

last updated 12/09

We have already built LifeTrac, the world's first, high performance, open source, multipurpose tractor. Our learnings from this project are:

  • Design-for-disassembly via bolt-together xyz beam design is feasible for building heavy equipment
  • Initial results indicate that complete, life-size Erector Set or Lego Set for real technology can be built using stock steel and components
  • Lifetime design, modularity, simplicity, and ease of maintenance are key features
  • Initial results indicate that DIY kits - reconfiguarable from small tractors to bulldozers just like Lego Blocks - with interchangeable motors and power units - are a viable route to widespread adoption of the technology
  • Cost performance in the DIY scenario appears to be a factor of 10 improvement over the competition

Performance Review

To date, LifeTrac has undergone over 1 year of field testing. Bucket work, CEB press power, backhoeing, power generator work, bale spiking, tree hole augering, disking, rototilling, soil pulverizing, and other uses were performed. During initial testing, the articulated joint cracked in half and was redesigned completely. Since then, there have been no mechanical problems, such that down time never lasted more than a few minutes due to ready ability to repair.

While long-term performance only will determine whether LifeTrac is worthy of its implied lifetime-design name - the results after 1 year of operation are promising. No visible leaks are to be found on any of the hydraulic motors and cylinders.

  • Hydraulic drive via a diesel engine reduces the mechanical complexity by eliminating the transmission-clutch-differential-drive train-steering-breaking, and replacing it with hydraulic flow, valves, and hydraulic actuators that perform all of the above functions
    • Thus, power transmission components are decoupled and made modular
  • Hydraulic system is robust and flexible. It allows devices on and off the tractor to be powered using 3 sets of 12 gpm outlets.
  • Articulated steering is an effective means of performing short-radius turns
  • Articulated joint both rotates and moves side-to-side, keeping 4 wheels on the ground under all conditions
  • Pressure can be varied everywhere with adjustable pressure reliefs
  • Custom implements, such as soil pulverizer, and many others can be used with LifeTrac


We welcome third party testing organizations to get involved in the evaluation process we are currently building LifeTrac prototype II.

Known Bugs

There is a number of known issues on LifeTrac I:

  • Too many valves - 6 different valves and flow regulators can be replaced with just 2, based on better flow strategy
  • Loose hydraulic hoses rubbing against tractor body and other hoses
  • Minor hydrauilic leaks from a number of loose or improper fittings
  • Engine is presently located at the front, creating poor weight balance for front loads over 2000 lb even with a 2000 lb counterweight on the back.
  • No roll-over protection and poor seat arrangement
  • Pinch points due to articulation
  • Shaky ride over rough terrain due the degrees of freedom of the articulating joint

All of these points will be addressed in the next prototype

LifeTrac Prototype II

The main difference in LifeTrac II will be a return to non-articulated design. While attractive from the perpective of low ground damage from turning and a constant traction of all 4 wheels on the ground, we decided that the added complexity, structural requirements, and danger associated with articulation are not worth the significant added effort. A non-articulated tractor is estimated to reduce the fabrication requirements by approximately a factor of 2 - allowing for an absolutely simple, robust design. This design still addresses gentle turning by wheel layout and and independent control of all 4 wheels. The design addresses traction by selectability between 2 or 4 wheel drive, as well as by the ability of LifeTrac II to use tracks instead of wheels.

The above considerations result in LifeTrac with the highest degree of simplicity and highest degree of flexibility - even compared to LifeTrac I. Based on our learnings, we believe that we can deliver the world's first, completely life-size Lego Set for heavy equipment. This will allow amateurs and professionals alike to tame machinery into useful service. In particular, the design specifications are:

  • Bolted, xyz construction with 4x4 inch square tubing as the stock steel of choice
  • All metal used is stock steel, and requires minor amounts of welding in lieu of bolted, xyz construction
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