Drawbar Pull Test Rig
Load Cells
Load cells and crane scales which are based on a Load Cell can be used to measure tractor pull. We'd like to prototype a 4-track, double-motor per track Cat D7 equivalent system, which totals 8*3600 lb or 28,800 lb of traction. See http://opensourceecology.org/wiki/Modular_Track_Unit_v18.01
Crane scale or load cell or hydraulic cylinder attached to a large tree trunk?
Crane Scales
Hydraulic Cylinder
We can just pull on a hydraulic cylinder - just attach a chain, and read the pressure from a Pressure Gauge. A 5" cylinder has pi*6*3000 lb force - 54 thousand - and little less in extension. So just perfect for measuring pull force of 30000 lb!
I think that's our answer for a near zero cost system, since we have 5" cylinders and pressure gauges lying around.