Couplings fall in two main categories: Rigid Couplings and flexible Couplings. In this post, we are going to make a comparison of the main differences between the rigid and flexible couplings.
These types of couplings provide a solid connection between two shafts, high precision and torque, but without misalignment absorption capabilities; it allows no movement between the two shafts and they require lubrication in many times. They cannot absorb vibrations, both shafts should be perfectly aligned to ensure a good performance and avoid damping transmission and possible breaks in the installation.
Example of some rigid coupling types:
- Muff or Sleeve coupling
- Flange coupling
- Clamp coupling
In the second main categories of couplings we can also make difference between two categories: Flexible Metallic Couplings and Flexible Couplings with an Elastic Element.
- Flexible Metallic Couplings: The power transmission is totally made by metallic compounds.
- Flexible Couplings with Elastic an Element: The power transmission is made by an elastic element placed between either hubs or flanges.
They compensate misalignments, movement or deflection. They are very useful when having quick and short starts. Normally they provide less torque transfer, but they have a high capacity to accommodate axial, parallel and angular misalignments, as well as reducing transmission of shock loads or vibration.
In case of the flexible couplings, they normally provide less torque transfer comparing with the rigid couplings, simply considering that these, are made of a piece of solid metal. However, we can obtain a wide range of torque capacity depending on the type of flexible coupling (having a higher torque capacity in metallic flexible couplings than in couplings with flexible element).
Example of some flexible coupling types:
- Flexible Metallic Couplings:
- Gear Coupling
- Disc Coupling or diaphragm Coupling (LAMAFLEX COUPLING)
- Chain Coupling
- Grid Coupling
- Flexible Couplings with Elastic Element
- Tyre coupling (UNEFLEX)
- Spider or Jaw coupling (ACOFLEX)
- Bush Pin type coupling
It is relevant to know each coupling type’s features when we are planning to make an installation.
It has to be verified if a coupling with a high torque transfer is required or not. In case of having even a slight misalignment, the operator should be placing a flexible coupling, and afterwards, the required misalignment capabilities should be checked to select the right flexible coupling, taking into account that it is not the same if we place a semi-flexible, elastic or a highly flexible coupling.