FLUID COUPLING

FLUID COUPLING

ABSTRACT

Various methods can be employed for coupling or joining two rotating shafts, such as for connecting an engine or motor to its load. Purely mechanical, rigid, or flexible coupling is used in many applications. In some applications, however, some form of fluid dynamic connector best meets service requirements.
i.e. ‘Fluid coupling’. No wear occurs; no mechanical contact of the power transmitting parts occurs.
    Let’s consider there are two ordinary electric fans that are set facing each other. One fan, connected to an electric outlet, is put into motion by turning on the electric current. As its blades rotate, the air current thus developed turns the blades of the other fan, which is not receiving any electric current.
Fluid coupling have been used for the transmission of torque through fluid flow. The term fluid coupling can be loosely used to describe any device utilizing a fluid to transmit power. The fluid is invariably a natural or synthetic oil because oil is capable of transmitting power, is a lubricant, and to absorb and dissipate heat. Manufacturers have tried water as the fluid in fluid couplings, but sealing problems (keeping water out of the bearings and oil out of the water) and corrosion prevented its use in any standard catalog drive.
     The constant fill fluid coupling is a hydrodynamic fluid coupling working on the ‘Fottinger principle’, which states that,
‘The torque developed by the electric motor is converted into kinetic energy by the primary side of the coupling that is directly connected to the motor shaft. It is then converted back into mechanical energy by the secondary side of the coupling’.
    Mechanical, rigid and flexible couplings have various disadvantages such as they have mechanical contact between transmitting elements, which leads to wear and tear of parts. Also some times it is necessary to transmit the full load at the starting, which requires large capacity electric motor etc. On the other hand, fluid coupling overcome all these disadvantages. Hence fluid coupling is beneficial to use.