What does the term "brake horsepower" refer to?

The term "brake horsepower" refers to the actual usable output of the engine, measured at the output shaft. This value represents the engine's power that can be harnessed for work before any losses due to friction, inefficiencies, or the power used by accessories are taken into account. It is a practical measure of the engine's performance in real-world applications, indicating how much power is available for driving loads.

In contrast, while maximum output before losses would encompass theoretical figures, it does not accurately represent what is available for practical use. The power absorbed by accessories pertains to the energy consumed by components that are necessary for engine operation but do not contribute to vehicle propulsion, further differentiating it from brake horsepower. Total thrust produced by the engine relates more to propulsion in jet engines rather than the power output in mechanical engines, making it a distinct concept. Thus, the focus on actual operational power in defining brake horsepower is crucial for understanding engine efficiency and performance in various applications.