Whether rigid, flexible or flexible couplings: It should be noted that shaft couplings are indispensable elements of any drive technology and create an effective connection between two shafts. The main task here is the reliable transmission of torque. This rotation can be realized by different types of couplings.

In order to understand how Couplings (specifically moving couplings for this article) work, it is important to differentiate between different types of couplings. In this article, we will begin by differentiating between shaft couplings according to the type of torque transmission. Finally, we will present two examples of movable couplings.

In addition to the transmission of torque, further requirements regularly arise. One possible additional requirement is the compensation of misalignment (compensation function). Couplings differ – measured on the basis of the stiffness of the intermediate link – into three types:

• RIGID COUPLING

• FLEXIBLE COUPLING AND

• MOVABLE COUPLING.

The balancing function mentioned above can be realized in different forms. Offsets can be realized by the following three compensation options can be minimized:

• AXIAL COMPENSATION

• RADIAL COMPENSATION AND/OR

• COMPENSATION IN ANGULAR DIRECTION OF ROTATION.

Different requirements arise depending on the individual application. Which direction of rotation do you want to compensate for? The desired offset option is an important criterion for selecting the right type of coupling. Do you need a rigid, flexible or flexible Coupling?

What is a rigid Coupling?

Rigid couplings do not compensate for misalignments and transmit torsional vibrations in a vaporized form. For this reason, rigid couplings can only connect aligned shafts.

What is a flexible Coupling?

There are different names on the market for torsionally flexible and flexible couplings:Torsionally flexible (flexible and highly flexible) coupling, elastomer coupling, shaft balancing coupling and claw coupling. Flexible Couplings consist of two coupling bodies and an elastomer ring gear. The claws (the name comes from the animal kingdom) of these claw couplings engage positively with the spider from both sides and the intermediate elastomer part compensates for misalignments (axial, radial, angular) and dampens vibrations. The following applies: High-vibration applications tend to require soft elastomeric elastomeric spiders with a high degree of damping and low torsional rigidity. Applications with low vibration tend to use harder elastomeric spiders with low damping properties and high torsional rigidity. The latter also allow higher torques. Would you like to read more about flexible Couplings? Then read more here.

In which cases are movable Couplings used?

Movable (torsionally rigid) couplings have a high torsional rigidity and enable high torques. They are also known as torsionally rigid or torsionally stiff couplings. The characteristic of torsional rigidity distinguishes them from torsionally flexible couplings. Does your application require both torsionally rigid torque transmission and compensation for shaft misalignments? Then flexible Couplings are the right choice. We determine the correct dimensioning of your flexible Coupling based on the torque to be transmitted and the required offset compensation. Our aim is to maintain maximum torsional rigidity while minimizing misalignments. The latter property distinguishes flexible from rigid Couplings and thus prevents possible bearing damage. Typical representatives of flexible couplings include the metal bellows coupling and the multi-plate coupling. We will therefore now take a closer look at these.

Movable Couplings: Metal bellows coupling from the manufacturers FLENDER and KTR

Metal bellows couplings impress with their reliability, operational safety, compactness and long service life. They are rigid in the direction of rotation, yet flexible in axial, radial and angular directions. The torsional strength is ensured by the geometric shape of the bellows. The flexible design of the metal bellows coupling enables it to absorb any restoring forces that occur and protects the Coupling from possible bearing damage. There are various metal bellows couplings, which can differ, for example, in the choice of bellows or the type of connection selected (bellows-hub connection or bellows-shaft connection). Individual requirements can only be mastered with the right dimensioning. For this, parameters such as the acceleration torque, the torsion angle or the resonance frequency must be determined. You will find two metal bellows couplings in our range: