Brake horsepower depends on head, flow, and efficiency.

• A. Head only
• B. Flow only
• C. Efficiency only
• D. Head, flow, and efficiency

Answer: (D)

Brake horsepower is the actual power you must supply to the pump shaft, and it depends on three things: how much water you’re moving (flow), how high you’re lifting or pushing that water (head), and how efficiently the pump uses input power to produce hydraulic energy (efficiency). If you move more water per second, more energy is needed. If you have to lift water higher or push against more pressure, more energy is required. Efficiency matters because it tells you how much of the input power actually becomes useful hydraulic power; lower efficiency means you need more shaft power to achieve the same output. So braking power rises with increased flow and head, and it also rises if efficiency drops. That’s why the best answer includes all three factors.