Which dyno uses hydraulics to apply and remove load through the dyno software?

• A. Waterbrake
• B. Eddy current
• C. Inertia
• D. Hydraulic

Answer: (A)

Hydraulic load control on a dynamometer uses fluid resistance to create drag, and the device that embodies this approach is the water brake. The water brake forces hydraulic fluid through a controlled path, and the dyno software adjusts valves or flow to increase or decrease resistance, allowing precise loading and unloading of the engine or test article. This is different from eddy current dynos, which rely on electromagnetic drag, and inertia dynos, which use the energy stored in a spinning flywheel rather than fluid resistance. So, when the load is applied and removed via hydraulic control commanded by the software, the water brake is doing the work.