Basics of Fluid Coupling

Fluid Coupling

Fluid Coupling:

• Fluid Coupling is basically one hydro kinetic transmission device that will act as a centrifugal pump and hydraulic turbine. Fluid coupling is also known as Hydraulic Coupling.
• A fluid coupling operates with a minimum amount of slip engineered into its design. A coupling cannot develop torque if both the input and output turbines are spinning at the same speed.

Basic Components of Fluid Coupling:

1. Pump: Driving impeller which will be mounted over the input shaft.
2. Turbine: Driven impeller which will be mounted over the output shaft.
3. Housing: Cover with an oil tight seal.

The input turbine is associated to the power supply, typically an electric or internal combustion piston engine. The output turbine is connected to the drive train of the vehicle or the drive system of a machine.

In a typical automobile, the fluid coupling is most commonly called a torque converter. The torque converter bolts onto the engine via the flywheel or starter ring and attaches to the transmission's input shaft. From there, it directly powers and moves the vehicle. 

How It Works:

Hydraulic fluid couplings transfer rotational force from a transmitting axis to a receiving axis. The coupling consists of two toroids -- doughnut-shaped objects -- in a sealed container of hydraulic fluid. One toroid is connected to the driving shaft and spins with the rotational force.

The spinning toroid moves the hydraulic fluid around the receiving toroid. The movement of the fluid turns the receiving toroid and in this manner turns the associated shaft.

Efficiency:

Although fluid couplings use hydraulic fluid within their construction, the mechanism loses a portion of its force to friction and results in the creation of heat. No fluid coupling can run at 100 percent efficiency. Excessive heat production from poorly maintained couplings can result in damage to the coupling and surrounding systems.

Advantages of Fluid Coupling:

There are following advantages of using fluid couplings

1. Easy starting with steady acceleration of driven element.
2. Drive train will be protected against overload.
3. Rotational vibrations will be dampened.
4. Direct on-line start electric motor might be used without using star-delta starter.
5. Automatic load speed adjustment possible by considering the concept of synchronous speed of two or more than two motor.