A fluid coupling is a transmission based on the kinetic energy of a fluid. Each fluid coupling shaft is rigidly coupled to an impeller, and between them circulates a fluid flow. The kinetic energy of the flow thrown by the driver impeller 1 is greater than the kinetic energy of the flow thrown by the driver impeller 2. The torque T transmitted by the fluid coupling is proportional to the difference of speed (slip) between the impellers.
Under operation at rated torque, the relative slip of the fluid coupling stays normally on the range 1.5% – 6.0%. The relative slip in % of a fluid clutch is defined as 100 x (n1 – n2) / n1
