Mictrotractor Review

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See results post - https://docs.google.com/spreadsheets/d/1QEP2lY5EdOeCjlH1s_MYqHCLYqDy4uDbdDqzyWPiYqo/edit#gid=1

and video:

OSE Microtractor Workshop from Ruth Dusseault on Vimeo.

Proofs of Concept

  • Track drive functions as expected, and 1/2" track links with 1" pins and 1.9" rollers indicate 10,000 - 20,000 lb torque rating for each track


Known Bugs

  • There are tracks with links either 1/2" or 3/8". One track piece gets stuck some times. Need to grind drive cog to more taper of teeth. -7/29/15
  • Track sections are difficult to weld. Flat bars can't be used, as a part of the links needs to have a standoff. Streamlining of track build should involve using a 5-10 link jig to facilitate welding. Main difficulty lay in having to regrind track sections.
  • Machine height of 58" is too tall - and appears to be not marketable as far as a consumer good

Good Points

  • Success metric - machine spins 360 degrees in place as expected.
  • Torque of 7500 lb at 2 tracks is significantly stronger than industry standards.
  • DIY build suggessful - track sections build with cutting, hole punching, and welding jigs.
  • Pipe wrench bending of idler shape works on 1/4" steel plate
  • Tensioner works as expected.
  • A 1" pin on track sections - if we compare that to 3" cylinders where a 1" pin holds 20,000 lb - is sufficiently robust to hold 6000 lb force with a safety factor of 3
  • Actual pin requirement is only 2000 lb for pin bending with single cog drive because 3 teeth catch the chain at all times.