Fluid coupling is also known as hydraulic coupling is a hydrodynamic device which is used to transfer rotational power from one shaft to another by the use of transmission fluid. It is used in automotive transmission system, marine propulsion system and in industries for power transmission. It is used as an alternative for the mechanical clutch.
It was discovered by Dr. Hermann Fottinger. He patented his discovery of fluid coupling and torque converter in the year 1950.
It consists of three main components
- Housing:It is also known as the shell. It has oil-tight seal around the drive shaft. It also protects the impeller and turbine from outside damage.
- Impeller or pump:It is a turbine which is connected to the input shaft and called as impeller. It is also known as pump because it acts as a centrifugal pump.
- Turbine: It is connected to the output shaft to which the rotational power is to be transmitted.
Working of Fluid Coupling
- As the prime mover moves, it rotates the impeller of the coupling. The impeller acts as a centrifugal pump and throws the fluid outward and directs it towards the turbine blade.
- As the high moving fluid strikes the turbine blades, it also starts rotating, after striking on the blades, the direction of the fluid is changed and it is directed towards the impeller again. The blades of turbine are designed in such a way that it can easily change the direction of the fluid. It is the changing of direction of the fluid that makes the turbine to rotate.
- As the impeller speed increases, the speed of the turbine also increases. After sometime the speed of both impeller and turbine becomes equal. In this way power is transmitted from one shaft to another by the use of fluid coupling.
- In same way torque converter works but the difference is that it has stator placed in between impeller and turbine for torque multiplication.
- It is used in automotive industries for the transmission of power from the engine to the wheel as alternative of clutch.
- It is used in marine propulsion systems.
- It is used in various industries for the power transmission.