fluid, e.g. hydraulic

Regulating or controlling by varying flow > Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted > the operation or power assistance being predominantly non-mechanical > fluid, e.g. hydraulic

Regulating or controlling by varying flow (for reversing F01D1/30; by varying rotor-blade position F01D7/00; specially for starting F01D19/00; shutting-down F01D21/00; regulating or controlling in general G05 ) > Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted (sensing elements alone F01D17/02; final actuators alone F01D17/10) > the operation or power assistance being predominantly non-mechanical > fluid, e.g. hydraulic