A fluid coupling is shown in Fig.The notations U, V, and Vr continue with their meanings, that is, the blade velocity, absolute velocity of fluid, 
and the velocity of fluid relative to the blade, respectively. Just as there are different designs of the pumps or the turbines with varying parameters (D1, D2, A1, A2, 
@1, @2,etc.), there are various designs of fluid coupling and torque converters.But these possibilities do not alter the analysis because the torque interactions depend on the tangential 
components of the fluid velocities.The velocity triangles can be drawn corresponding to the two elements, in order to 
determine the interaction of the torques/energy/power.It is quite possible that the outlet of the pump impeller and the inlet of the 
turbine runner may be in the radial direction [as in Fig.Also, the velocity triangles are as practiced with refer ence to the respective machines.The additional subscripts p and t signify the pump and the turbine, respectively.Naturally, the 
velocity triangles become the reference for analysis.9.3(b)].