Hydraulic coupling

Fluid coupling is an energy-consuming mechanical control devices, speed deeper (lower speed) the greater the loss, especially constant torque load, since the original transmission input power constant, the speed loss into a loss of power ratio increases. For fan and pump load,  Hydraulic adapters load torque at speed squared rate changes, the original transmission input power measured at the square of speed decreased, loss of power is relatively small, but the output power is reduced by the cube of speed ratio, speed efficiency is still low. Governor hydraulic coupling efficiency curve shows the average efficiency of around 50%