The engine crankcase is drained and refilled with a measured amount of new oil conforming to specifications in the operator's manual. The tractor is then limbered-up for three hours or more on drawbar work in accordance with the manufacturer's published recommendations. The manufacturer's representative is present to make appropriate decisions regarding mechanical adjustments. The manufacturer's representative makes carburetor, fuel pump, ignition and governor control settings which remain unchanged throughout all subsequent runs. The governor and the manually operated governor control lever are set to provide the high-idle speed specified by the manufacturer for maximum power.
Maximum power is measured by connecting the power take-off to a dynamometer.
The dynamometer load is then gradually increased until the engine is operating at the rated speed specified by the manufacturer for maximum power. This test lasts two hours. Six different power levels are used. This test also lasts two hours with a 20 minute test time at each specified load. Since a tractor is generally subjected to varying loads, the average of the result in this test serve well for predicting the fuel consumption of a tractor in general use.