Which factor is measured during thresher testing?

In the context of thresher testing, measuring air velocity is crucial because it directly influences the performance of the thresher. The air velocity helps determine how effectively the thresher is able to separate the grain from the chaff. Higher air velocities are often necessary to ensure that lighter particles, like chaff, can be blown away while heavier grains remain in the collection system. This efficiency impacts crop yield and overall operational effectiveness.

Air temperature, humidity, and air pressure are important atmospheric factors but do not specifically gauge the performance and separation efficiency of a thresher. Rather, they can affect the moisture content of the grain or influence the operational environment, but they are not the primary metrics assessed during the thresher testing process. Hence, focusing on air velocity provides a more relevant measure of the thresher's functionality in agricultural practices.