A fluid coupling or hydraulic coupling is a hydrodynamic or ‘hydrokinetic’ device used to transmit rotating mechanical power. It has been found in automobile transmissions as an alternative to a mechanical clutch.

Fluid couplings are hydrodynamic devices that transmit rotation between shafts by acceleration and deceleration of hydraulic liquid. Shafts are used industrially to supply rotary motion to a wide spectral range of vehicles and gear and shaft couplings are key to providing secure rigid, flexible or non-linear connection between shafts, tires and rotary equipment.

Fluid couplings consist of a housing containing an impeller in the input or driving shaft and a runner in the output shaft. Both these contain a fluid which is usually oil that is added to the coupling through a filling plug on the casing. The impeller, which acts as a pump, and the runner, which acts as a turbine, are both bladed rotors. The parts of fluid couplings are generally crafted from metallic materials-aluminum, metal or stainless. Fluid couplings are found in the automotive, railroad, aerospace, marine and mining industries. They are found in the transmissions of automobiles instead of mechanical clutches. Forklifts, cranes, pumps of all types, mining machinery, diesel trains, aircrafts and rotationally-powered commercial machinery all use liquid coupling when a credit card applicatoin requires variable speed procedure and a startup without shock loading the machine. Manufacturers utilize these couplings for connecting rotary products such as drive shafts, series shafts, generators, tires, pumps and turbines in a variety of automotive, coal and oil, aerospace, water and waste materials treatment and construction industries.

In a fluid coupling, the impeller and rotor are both bowl-shaped and also have many radial vanes. They face each other but unlike equipment couplings haven’t any mechanical interconnection rather than touch. Fluid is definitely directed by the pump into the impeller. The driving turbine or pump is usually rotated by an internal combustion engine or electric electric motor imparting both linear and rotational motion to the liquid. The velocity and energy is usually transferred to the liquid when the impeller rotates. It is then converted into mechanical energy in the rotor. Every fluid coupling has differing stall speeds, which may be the highest velocity that the pump can change when the runner can be locked and maximum input power is applied. Slipping always occurs since the input and output angular velocities are identical, and then the coupling cannot reach complete power efficiency-some of it will always be lost in the fluid friction and turbulence. Versatile shaft couplings such as fluid couplings are essential because during operation, some types of shafts tend to shift, causing misalignment. Versatile couplings provide efficient accommodation for moderate shaft misalignment that occurs when the shafts’ axes of rotation become skewed. Shaft movement is caused by bumps or vibration and it outcomes in parallel, angular or skewed shaft misalignment.
Quick fluid coupling china release coupling (quick connect-disconnect coupling), is usually a mechanical device,that provides a fast, convenient way to repeatedly connect and disconnect any liquid line.