Subject:
Fluid coupling:
The fluid coupling is no longer used nowadays for driving an automatic transmission. Nowadays the torque converter is used for that purpose. The torque converter provides better efficiency. This can be seen in the graph. See the Torque Converter page.
The efficiency of a fluid coupling is almost equal to that of the plate clutch. However, at almost complete coupling the efficiency completely collapses. The drive would then be lost. A torque converter does not have these characteristics. Due to the internal vanes, the torque is already increased at low speed.
