All tractors tested at the Nebraska Tractor Test Laboratory were certified by their manufacturers as being stock model machines, conforming to specifications filed with the application for test. No special or high-test fuels were used except as recommended by the manufacturer as necessary. All results within the official tractor test report were actually attained in tests and are without correction or allowances for friction, temperature, altitude, etc. The results were initially accomplished with the tractor in charge of skilled operators employed by the University. Unless otherwise noted, each tractor was apparently in good condition at the end of the testing and there was no evidence of undue wear or of any weakness that might require ...