MicroTrac 2015

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Development

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Results - July 2015

https://www.facebook.com/OpenSourceEcology/videos/vb.66469461561/10154088233271562/?type=2&theater

Microtracprototype.jpg

Introduction

Prototype 2 of the MicroTrac. See Power Cube Genealogy for Power Cube.

Working Document

Parts Library

Power Cube v7s

Component Area Part Qty Price Weight
Cage Hydraulic Pump .677 cu in, 10.1 gmp @3600 RPM, 3000 PSI max, 4000 RPM max 1 $185 9 lbs
Cage NT filter or SC filter 1 $17 2 lbs
Cage or type E coupler half 1/4" key 2.5" o'all long 2 $9.86 1 lbs
Control 3 spool valve (about 1900-3400 PSI relief setting) 1 $220 35 lbs
Drive Wheel 1
17.5 HP gas engine 1 60 lbs
Hydraulic Reservoir 1 10 lbs
Battery 1 $23 20 lbs
Frame Metal 2x2x1/8" square tube 29" long 6 $30.95 44 lbs
Frame Metal 2x2" square tube 24" long 4 $17 24 lbs
Frame Metal 2x2" square tube 20" long 8 $28.46 40 lbs
Frame Metal 2x2" square tube 7" long 2 $2.49 4 lbs
Frame Metal 7x25" plate 1/4" thick 1
Optional/Unused L095 coupler half 1" shaft 1/4" key 1-1/16" long 1 $15.28 1 lbs
Optional/Unused L095 hytex coupler insert 1 $18.29 0 lbs
Optional/Unused L095 coupler half 3/4" shaft 3/16" key 1-1/16" long or 5/8" 1 $15.28 1 lbs
Total $582 251 lbs

Design

Goals

  • 41" (1041.4mm) width
  • 54" height

Design Proposals

Tracks with rotors

draft File:Ose-microtrac-20150429.skp

  • laying out ideas for idler and motor

PC7s Modification Suggestions

  • Separate mount for the pressure relief valve and output port. This mounts the pressure relief valve and output port so the port is facing up and the hose has only a gradual 90 degree bend, with full 3/4" plumbing to the port:

PC7sOutputPanel.png

  • Split the controls apart from the hydraulic connections. This will separate the throttle and keyswitch into a control panel that can be easily relocated anywhere on the PC7s frame. This will allow all controls for to be grouped together. The hydraulic connections can be streamlined for more direct fluid flow and thus less energy loss.

Here is a suggested panel for PC7s controls:

PC7sControls.jpg

Note also that the gas filler cap has been moved nearer the center of the tank to reduce leaking due to sloshing.

  • Several items will need to be connected to the frame that do not require full structural strength (ex: Control Panel & Output Pane). Bolting these to the frame are a challenge using conventional nut and bolt hardware. It is simplified by using special nuts with conventional bolts, such as the one shown below:

NDWeldNut.jpg ND Weld Nut

Source: ND Weld Nut

These are intended to be welded, but should work in this application without welding.

Past Design Work

Graham_Microtrac

Tracks

Track Proposal Google Drive Folder

Reference Works

Toro makes a series of comparable machines, called the "Dingo". Toro publishes information about them, which make excellent references into their design and operation:

Toro Dingo Website

Toro uses a dual gear pump in Model 323, directly coupled to the engine shaft. One pump is 4 GPM and the other is 10.8 GPM. It can switch from one pump to the other for higher speed or higher torque. They say the low flow setting is good for training.

They use two hubs and two rubber disc couplers for power transmission - we haven't use this setup, but I've seen them before

http://www.dingo.com.au/dingo-design/dingo-male-mount-plate/

http://www.skidsteers.com/toro-dingo-mounting-plate.html