A system and method can include a rotational component, a fluid pump, and a shaft transferring rotational power toward the fluid pump. A fluid circuit can include a valve and the fluid pump wherein pump is configured to motivate fluid toward the valve disposed downstream of the pump. The system can be configured to raise fluid pressure at the pump outlet by closing the valve to thereby effect an increased braking load on the shaft. The rotational component can be an electric machine mechanically coupled to a gas turbine engine. The fluid circuit can include a heat exchanger configured to transfer heat between the rotational component and the fluid. The system can include a second heat exchanger configured to transfer heat from the fluid to a heat sink. A processing system can be configured to receive a command to increase the hydraulic braking load to the rotational component by closing the valve to raise fluid pressure at the pump outlet based on a braking command.