How is the overall efficiency of a hydraulic motor best defined?

The overall efficiency of a hydraulic motor is best defined as the output horsepower divided by the input horsepower. This ratio provides a clear measure of how effectively the hydraulic motor converts the energy it receives into useful work output. In practical terms, it reflects the percentage of input energy that is effectively transformed into mechanical energy, with the remainder typically lost to factors such as heat, friction, and other inefficiencies within the system.

By using output horsepower divided by input horsepower, it becomes straightforward to assess the performance of the hydraulic motor. A higher efficiency indicates that a larger proportion of input energy is being converted into work, which is crucial for optimizing the performance of hydraulic systems in various applications.

While the other options present different relationships, they do not accurately define overall efficiency in the context of hydraulic motors. For example, multiplying output horsepower by input torque does not yield a measure of efficiency. Similarly, the ratios involving torque do not directly relate to the efficiency in terms of horsepower, which is the standard metric for defining the performance of hydraulic motors.