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About Shaft Couplings

A shaft coupling is a mechanical part that connects the drive shaft and driven shaft of a motor, etc., so as to transmit power. Shaft couplings expose mechanical flexibility, offering tolerance for shaft misalignment. Therefore, this coupling versatility can reduce uneven don on the bearing, tools vibration, and other 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 tranny such as for example in wind and hydraulic electrical power machinery.
In NBK, the former is called a coupling and the latter is named a shaft coupling. Below, we will speak about the shaft coupling.
Why Do We Need Shaft Couplings?
Even if the motor and workpiece are directly connected and properly fixed, slight misalignment can occur over time due to changes in temperature and adjustments over an extended period of time, causing vibration and damage.
Shaft couplings serve as an important link to minimize effect and vibration, allowing easy rotation to be transmitted.
Flexible Flanged Shaft Couplings
Characteristics
These are the most famous flexible shaft couplings in Japan that comply with JIS B 1452-1991 “Flexible flanged shaft couplings”.
A simple structure manufactured from a flange and coupling bolts. Easy to set up.
The bushing between the flange and coupling bolts alleviates the effects 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 getting transmitted.
2 types can be found, a cast iron FCL type and a carbon steel?FCLS type Flexible Shaft Couplings

Shaft Coupling Considerations
In choosing couplings a designer primary needs to consider motion control varieties or power transmission types. Most motion control applications transmit comparatively low torques. Power transmission couplings, in contrast, are designed to carry average to great torques. This decision will narrow coupling choice relatively. Torque tranny along with optimum permissible parallel and angular misalignment ideals are the dominant considerations. Most couplings will publish these values and using them to refine the search should produce deciding on a coupling style less complicated. Maximum RPM is another critical attribute. Maximum axial misalignment may be a consideration as well. Zero backlash is an essential consideration where opinions is employed as in a motion control system.
Some power transmitting couplings are created to operate without lubricant, which can be an advantage where maintenance is a problem or difficult to perform. Lubricated couplings quite often require covers to keep carefully the grease in. Various couplings, including chain, gear, Oldham, etc., can be found either because lubricated metal-on-metal varieties and as metallic and plastic material hybrids where generally the coupling element is made of nylon or another plastic-type to remove the lubrication requirements. There exists a reduction in torque ability in these unlubricated forms compared to the more conventional designs.
Important Attributes
Coupling Style
Almost all of the common models have already been described above.
Maximum RPM
Most couplings have a limit on their maximum rotational acceleration. Couplings for high-acceleration turbines, compressors, boiler feed pumps, etc. usually require balanced models and/or balanced bolts/nuts allowing disassembly and reassembly without raising vibration during procedure. High-speed couplings can also exhibit windage effects in their guards, which can result in cooling concerns.
Max Transmitted Horsepower or perhaps Torque
Couplings tend to be rated by their maximum torque capability, a measurable quantity. Vitality is a function of torque times rpm, thus when these values are stated it is normally at a specified rpm (5HP @ 100 rpm, for example). Torque values are the additionally cited of both.
Max Angular Misalignment
One of the shaft misalignment types, angular misalignment capability is usually explained in degrees and represents the maximum angular offset the coupled shafts exhibit.
Max Parallel Misalignment
Parallel misalignment capacity is generally given in linear products of inches or millimeters and represents the utmost parallel offset the coupled shafts exhibit.
Max Axial Motion
Sometimes called axial misalignment, this attribute specifies the utmost permissible growth between the coupled shafts, given generally in inches or perhaps millimeters, and will be due to thermal effects.