Microtractor Part Sourcing

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Overview

Part Sourcing for the Microtractor. Much design work has been merged into the Power Cube.


Microtracpartsbuild.jpg

Engine

Sourcing


Power Cube (MicroTrac engine cube) Details

Engine-side coupler half, 1" shaft, $9.86, Type E
Spider insert, 1" shaft, coupler half, $14.36, type E
Pump-side coupler half, 5/8" shaft, $9.86, Type E
  • The coupler halves and spider are shown in the pictures, from McMaster Carr page 1157

Power Calculations

Pump

Hydraulics Calculations from [1]
  • From [2] - Pumping = 1 Hp = 1 GPM x 1500 Psi - (linear relationship i.e. 2 GPM @ 1500 Psi = 2 Hp)
    • For the above pump, 14.2 gpm with 3000 psi indicates 28.4 hp requirement
  • Hp to drive hydraulic pump = Psi x GPM / 1714
    • For the above .97 cu in pump, 3000*14.2/1714 = 24 hp
    • If we run at 2200 psi => 18 hp required
    • For .86 cu in pump, need 3000*12.6/1714 = 22 hp
    • For the same with 2500 psi, 18.3 hp

Power Available

  • Assuming 85% pump efficiency, we have 17.5*.85=14.8 hp power available to the machine

Wheel Motor Calculations

  • 32 cu in wheel motor: 20 gpm, 5170 in lb torque, 145 rpm
    • Using 12 gpm, 5170 in lb torque, at 87 rpm - uses 7 hp of the engine

Spider Torque Rating

The Hytrel coupler spider has a 401 in lb torque rating. This is at 3600 rpm. If this pump is driving a hydraulic motor at 87 rpm (wheel motor at 12 gpm fluid flow, at its rated torque), what would be the maximum torque that the 87 rpm could have? 401*3600/87 = 16600 in lb. That is well within the 5130 in lb torque of the wheel motor. Coupler spider will hold up.


Engine

Power Cube

Wheels

32 cu in wheel motor, 5130 in oz torque, 145 rpm at 20 gpm
  • one set of drive wheels in the middle balanced with the engine so the Microtrac can be rotated easily, with a motor on the side
  • doubled up for traction
  • have support wheels on the back sides so it doesn't tip easily
  • drive wheels the same as lifetrac, 30" high 10" wide


Resource Map

Reviewers:

Coupler info:

Notes

  • On calculations (right picture) - formula for horsepower to drive pump (with 1714 factor) includes the efficiency of the pump (about 85%)


See Also