Everything To Know About Fluid Coupling

Everything To Know About Fluid Coupling - Premium Transmission

Hydraulic coupling is another term for fluid coupling. It is a hydrodynamic instrument that utilizes transmission fluid to transmit rotational motion from one shaft to another. It is employed in automobile transmission systems, marine propulsion systems, and a variety of industrial applications. It is used in lieu of a mechanical clutch.

Dr. Hermann Fottinger found it. In 1950, he patented his invention of the fluid coupling and torque converter.

Principal Components of Fluid Coupling

It is composed of three primary components:

1. Affluence

It is sometimes referred to as the shell. It has an oil-tight gasket that completely encircles the driving shaft. Additionally, it shields the rotor and turbine from external harm.

2. Reciprocating impeller or pump

An impeller is a turbine that is attached to the input shaft. It is also referred to as a pump due to the fact that it functions as a centrifugal pump.

3. Wind turbine

It is attached to the output shaft that will receive the rotational power. The impeller is attached to a power source called the prime mover (internal combustion engine/ motor). The turbine is linked to the output shaft, which is used to transport rotational energy. 

The impeller, as well as turbine, are contained inside an oil-tight, hermetically sealed enclosure. Transmission fluid is used to fill the housing.

Principle of Operation

The fluid’s operation may be simply described by considering two fans, one of which is linked to the power source and the other which is not. When the electricity is turned on, the first fan’s air begins to blow toward the secondary fan (which is not connected to the power source). When the first fan is operating at a slower speed, it is unable to drive the second fan. However, when the powered fan’s speed grows, the speed of air impacting the blades of the second fan increases as well, and it begins to revolve. After a while, it reaches the same velocity as the first fan.

The fluid coupling operates on the same basis. In this case, the impeller serves as the primary fan while the turbine serves as the secondary fan. The impeller and turbine are both contained inside an oil-tight enclosure. The impeller is attached to the prime mover’s input shaft, while the turbine is connected to the output shaft. 

When the prime mover rotates the impeller, the fluid in the housing is subjected to centrifugal force and is directed toward the turbine blades by the impeller’s curved vanes. When the fluid collides with the turbine blades, the turbine begins to rotate. With an increase in impeller speed, the turbine’s velocity rises and approaches that of the impeller. Following passage through the turbine blades, the fluid returns to the impeller.

Working of Fluid Coupling

  1. The primary mover turns the coupling’s impeller as it travels. The impeller functions as a centrifugal pump, propelling the fluid outward and toward the turbine blade.
  2. As the fast-moving fluid collides with the turbine blades, it begins to rotate; after colliding with the blades, the fluid’s direction changes and it is redirected into the impeller. The turbine’s blades are constructed in such a manner that they can readily shift the direction of the fluid. The turbine rotates due to the fluid changing direction.
  3. As the impeller speed rises, the turbine speed increases as well. After a period of time, the impeller and turbine speeds become equal. Through the use of fluid coupling, power is transferred from one shaft to the other in this manner.
  4. Torque converters operate similarly to turbochargers, with the exception that a stator is put between the impeller and turbine to double the torque.

Applications of Fluid Coupling

  • It is used in the automobile industry in place of the clutch to transmit energy from the motor to the wheels.
  • It is a propellant material used in maritime propulsion systems.
  • It is utilized to transmit energy in a variety of Industrial sectors for applications like Centrifugal Fans, centrifugal pumps, Conveyors, Crushers, Ball mills, mixers,etc


We have learned in-depth about what fluid coupling is, its major components, how it works, and how it is used. However, to make the most use of this device, it’s crucial to get a high-quality product. And, this is where Premium Transmission can help! To know more about how we can help, contact us today