About Shaft Couplings
A shaft coupling is a mechanical component that connects the drive shaft and driven shaft of a electric motor, etc., in order to transmit power. Shaft couplings introduce mechanical flexibility, offering tolerance for shaft misalignment. Therefore, this coupling overall flexibility can reduce uneven wear on the bearing, gear vibration, and additional mechanical troubles due to misalignment.
Shaft couplings can be found in a tiny type mainly for FA (factory automation) and a large casting type used for large power transmitting such as in wind and 
hydraulic ability machinery.
In NBK, the former is called a coupling and the latter is named a shaft coupling. Here, we will discuss the shaft coupling.
Why Do WE ARE IN NEED OF Shaft Couplings?
Even if the electric motor and workpiece are directly connected and effectively fixed, slight misalignment can occur over time because of changes in temperature and changes over a long period of time, leading to vibration and damage.
Shaft couplings serve seeing that an important connect to minimize impact and vibration, allowing smooth rotation to become transmitted.
Flexible Flanged Shaft Couplings
Characteristics
These are the most used flexible shaft couplings in Japan that adhere to JIS B 1452-1991 “Flexible flanged shaft couplings”.
A simple structure made of a flange and coupling bolts. Easy to install.
The bushing between your flange and coupling bolts alleviates the effects of torque fluctuation and impacts during startup and shutdown.
The bushing can be replaced by just removing the coupling bolt, enabling easy maintenance.
Permits lateral/angular misalignment, and reduces sound. Prevents the thrust load from simply being transmitted.
2 types can be found, a cast iron FCL type and a carbon metal?FCLS type Flexible Shaft Couplings
Shaft Coupling Considerations
In choosing couplings a designer initial needs to consider motion control varieties or power transmission types. Most action control applications transmit comparatively low torques. Power tranny couplings, in contrast, are designed to carry modest to huge torques. This decision will narrow coupling choice somewhat. Torque transmission along with maximum permissible parallel and angular misalignment values will be the dominant considerations. Most couplings will publish these values and using them to refine the search should help to make picking a coupling style a lot easier. Maximum RPM is another important attribute. Optimum axial misalignment may be a consideration as well. Zero backlash is normally a significant consideration where responses is employed as in a action control system.
Some power transmitting couplings are made to operate without lubricant, which may be an advantage where maintenance is a concern or difficult to perform. Lubricated couplings generally require includes to keep carefully the grease in. Various couplings, including chain, equipment, Oldham, etc., are available either since lubricated metal-on-metal varieties and as steel and plastic-type hybrids where generally the coupling element is made of nylon or another plastic-type to remove the lubrication requirements. You will find a reduction in torque capacity in these unlubricated varieties when compared to more conventional designs.
Important Attributes
Coupling Style
Almost all of the common designs have already been described above.
Maximum RPM
Most couplings have a limit on their maximum rotational swiftness. Couplings for high-rate turbines, compressors, boiler feed pumps, etc. generally require balanced styles and/or balanced bolts/nuts allowing disassembly and reassembly without increasing vibration during procedure. High-speed couplings may also exhibit windage results in their guards, which can bring about cooling concerns.
Max Transmitted Horsepower or Torque
Couplings tend to be rated by their maximum torque capacity, a measurable quantity. Power is usually a function of torque moments rpm, hence when these values are stated it is usually at a specified rpm (5HP @ 100 rpm, for example). Torque values will be the more commonly cited of the two.
Max Angular Misalignment
Among the shaft misalignment types, angular misalignment capacity is usually mentioned in degrees and represents the maximum angular offset the coupled shafts exhibit.
Max Parallel Misalignment
Parallel misalignment capacity is generally given in linear systems of inches or millimeters and represents the maximum parallel offset the coupled shafts exhibit.
Max Axial Motion
Sometimes called axial misalignment, this attribute specifies the maximum permissible growth between the coupled shafts, offered generally in inches or perhaps millimeters, and will be caused by thermal effects.