Couplings are mainly divided into two categories: rigid couplings and flexible couplings. In this article, we will compare the main differences between rigid and flexible couplings.

Rigid couplings

These types of couplings provide a strong connection between two shafts, with high precision and high torque, but have no misalignment absorption capacity; it does not allow movement between the two shafts and requires multiple lubrication. They cannot absorb vibrations, and the two shafts should be perfectly aligned to ensure good performance, avoid transmission damping and possible breakage in the installation.

Some examples of rigid coupling types:

Sleeve couplings

Flange couplings

Clamp couplings

Flexible couplings

In the second main category of couplings, we can also distinguish two types of flexible couplings: flexible metal couplings and flexible couplings with elastic elements.

Flexible metal couplings: Power transmission is made entirely of metal compounds.

Flexible couplings with elastic elements: Power transmission is done by elastic elements placed between hubs or flanges.

They can compensate for misalignment, movement or deflection. Very useful for fast and short-distance starts. Usually they offer less torque transmission, but they have a high ability to accommodate axial, parallel and angular misalignments and reduce the transmission of shock loads or vibrations.

As far as flexible couplings are concerned, they usually offer less torque transmission than rigid couplings, because flexible couplings are made from a solid piece of metal. However, we can get a wide range of torque capacity depending on the type of flexible coupling (metal flexible couplings have a higher torque capacity than couplings with flexible elements).

Examples of some flexible coupling types:

Flexible metal couplings:

Gear couplings

Diaphragm couplings or diaphragm couplings (LAMAFLEX COUPLING)

Chain couplings

Grid couplings

Flexible couplings with elastic elements:

Tire couplings (UNEFLEX)

Spider or claw couplings (ACOFLEX)

Bushing pin couplings

Conclusion

When we plan an installation, it is important to know the characteristics of each coupling type.

It is necessary to verify whether a coupling with high torque transmission is required. If there is a slight misalignment, the operator should place a flexible coupling and then check the required misalignment capacity to select the correct flexible coupling, taking into account that the situation would be different if we placed a semi-flexible, elastic or high-flexible coupling.