About Shaft Couplings

A shaft coupling is a mechanical element that connects the travel shaft and driven shaft of a engine, etc., so as to transmit ability. Shaft couplings bring in mechanical flexibility, offering tolerance for shaft misalignment. Therefore, this coupling flexibility can reduce uneven wear on the bearing, tools vibration, and various other mechanical troubles because of misalignment.

Shaft couplings can be purchased in a tiny type mainly for FA (factory automation) and a sizable casting type used for huge power transmission such as for example in wind and hydraulic power machinery.
In NBK, the former is called a coupling and the latter is called a shaft coupling. Here, we will discuss the shaft coupling.
Why Do We Need Shaft Couplings?
Even if the engine and workpiece are directly connected and correctly fixed, slight misalignment can occur over time due to changes in temperature and changes over a long period of time, creating vibration and damage.
Shaft couplings serve because an important link to minimize affect and vibration, allowing simple rotation to be transmitted.
Flexible Flanged Shaft Couplings
These are the most famous 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 set up.
The bushing between the flange and coupling bolts alleviates the consequences of torque fluctuation and impacts during startup and shutdown.
The bushing could be replaced simply by removing the coupling bolt, enabling easy maintenance.
Permits lateral/angular misalignment, and reduces noise. Prevents the thrust load from being transmitted.
2 types are available, a cast iron FCL type and a carbon steel?FCLS type Flexible Shaft Couplings

Shaft Coupling Considerations
In picking couplings a designer first must consider motion control varieties or power transmission types. Most movement control applications transmit comparatively low torques. Power transmission couplings, in contrast, are made to carry average to large torques. This decision will narrow coupling choice somewhat. Torque tranny along with optimum permissible parallel and angular misalignment values will be the dominant considerations. Most couplings will publish these values and with them to refine the search should produce deciding on a coupling style less difficult. Optimum RPM is another essential attribute. Optimum axial misalignment may be a consideration aswell. Zero backlash is usually an essential consideration where opinions can be used as in a movement control system.
Some power transmitting couplings are made to operate without lubricant, which is often an advantage where maintenance is a problem or difficult to execute. Lubricated couplings frequently require addresses to keep carefully the grease in. Various couplings, including chain, equipment, Oldham, etc., are available either because lubricated metal-on-metal kinds and as steel and plastic-type hybrids where generally the coupling element is made of nylon or another plastic to eradicate the lubrication requirements. There exists a reduction in torque ability in these unlubricated varieties compared to the more conventional designs.
Important Attributes
Coupling Style
Almost all of the common designs have been described above.
Maximum RPM
The majority of couplings have a limit on the maximum rotational rate. 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 can also exhibit windage effects within their guards, which can cause cooling concerns.
Max Transmitted Horsepower or Torque
Couplings tend to be rated by their optimum torque capability, a measurable quantity. Ability is normally a function of torque moments rpm, and so when these values are stated it is generally at a specific rpm (5HP @ 100 rpm, for instance). Torque values are the additionally cited of the two.
Max Angular Misalignment
Among the shaft misalignment types, angular misalignment capacity is usually mentioned in degrees and represents the utmost angular offset the coupled shafts exhibit.
Max Parallel Misalignment
Parallel misalignment capacity is normally given in linear devices of inches or millimeters and represents the maximum parallel offset the coupled shafts exhibit.
Max Axial Motion
At times called axial misalignment, this attribute specifies the utmost permissible growth between the coupled shafts, granted generally in inches or millimeters, and can be caused by thermal effects.