A fluid coupling is a device used to transmit power between two rotating shafts using a fluid, typically oil. It consists of two main components: an impeller and a turbine. The impeller, connected to the engine, spins and creates a flow of fluid that drives the turbine, which is connected to the driven machinery. This allows for smooth acceleration and deceleration, reducing wear on mechanical parts. One of the key advantages of a fluid coupling is its ability to absorb shock loads, making it ideal for applications like automobiles and industrial machinery. By providing a cushion between the engine and the load, it enhances performance and extends the lifespan of the equipment.