hydraulic loss मीनिंग इन हिंदी

The company's early transmissions also used a patented torque converter which used stator force to reduce hydraulic losses by using a reaction arm to increase the hydraulic pressure when the stator was stalled.
Also how is the efficicency curve of the fan derived ( if it can be derived-Im not talking about the friction loss in bearings etc but the hydraulic losses which depend on geometry )?