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. All engine adjustments are the same as those used in the power take-off tests. These runs are made around the entire test course, which has two 180 degree turns with a minimum radius of 50 feet.
Maximum power is measured on straight, level sections of the test course.
One gear slower than those above will be tested with the load reduced to give approximately 15 percent slip. One gear over 8 MPH but less than 10 MPH will also be tested. Sound Measurement Sound is recorded during each of the drawbar power and fuel consumption runs as the tractor travels on a straight section of the test course. Bystander sound readings are taken with the microphone placed 25 feet from the line of travel of the tractor. Additional Tests Tractors equipped with a front wheel drive that can be engaged or disengaged from the driver's seat may require additional drawbar tests.