In addition to transmission of the rotation and torque, couplings perform other tasks according to their design:

  • Limitation or interruption according to the maximum torque allowed in order to protect the components
  • Damping of vibrations between individual machines
  • Holding attaching parts (e.g. brake drum)
  • Electrical insulation
  • Compensation for displacement with low restoring forces

Shaft misalignment is the result of incorrect mounting or operation and, in rigid connections between two components, can lead to unnecessarily high static load on the shaft bearing.

In many cases, simply ensuring that components are correctly adjusted will not be enough to avoid these high loads on the bearings as frames vary according to elastic deformation and dynamic and static machine states are different due to thermal influences. When using couplings, the restoring force should be taken into consideration in the layout of bearings with a high load.

Jaw coupling

Axial plug-in coupling

  • Elastomers with different shore hardnesses allow for different damping characteristics
  • Compensates for angular, longitudinal and axial displacement
  • Maintenance-free

Jaw couplings guarantee that transmission takes place with damping of the rotational vibrations. They also absorb shocks which occur due to engines working asymmetrically. Jaw couplings are torsionally flexible and transmit torque via a form-fit connection. They are also fail-safe. The vibrations and shocks occurring during operation are effectively dampened and eliminated. Jaw couplings can compensate for axial, radial and angular displacement of the shafts to be connected.

Two congruent coupling halves, the insides of which are equipped with concave claws, are offset against each other in circumferential direction by half a spacing and are designed in such a way that an involute gear rim can be fitted between them. The individual teeth of this intermediate link has a convex profile in order to avoid edge pressure caused by displacement of the shafts.

Unlike flexible couplings whose intermediate links are subjected to bending stress and therefore wear more quickly, the flexible teeth of the jaw couplings are only subject to compressive stress. This type of coupling therefore has the advantage that the individual teeth are more resilient.

Curved-tooth gear coupling

Easy mounting

  • Maintenance-free
  • Compensates for angular and axial displacement

Curved-tooth gear couplings are flexible shaft connections for positive-locking torque transmission and are especially suited to compensating for axial, radial and angular displacement.

Unlike clutch hubs with a straight-cut gear, curved-tooth gear couplings prevent edge pressure when interlocking in the case of angular and radial displacement, meaning they are almost non-wearing when used.

The combination of steel hubs and polyamide sleeves allows for maintenance-free, long-term operation with very low friction coefficients when the teeth interlock. Thanks to the double-gimbal operation of the curved-tooth gear couplings, the restoring force in the case of angular and radial displacement is negligible and there are no periodical variations in the angular speed.

Laminae coupling


  • Torsion-resistant
  • Very high torques can be transmitted
  • Only angular and axial displacement permitted
  • Maintenance-free

The laminae coupling is a backlash-free, torsionally rigid, maintenance-free, all-steel coupling. The laminae that are extremely rigid in sense of rotation are made of high-strength, stainless spring steel and enable a compensation for high displacements with low restoring forces.

The "heart" of the steel laminae coupling is the laminae packings and their connection to the hubs or spacers. High-strength, special dowel screws that are alternately screwed with hubs and spacers enable a combination of frictional engagement and positive locking. Thus a high power density and at the same time easy displacement and low restoring forces are guaranteed.


KTR is a leading manufacturer of high-quality drive components such as mechanical couplings, clamping sets and torque limiters.



VMA develops, manufactures and distributes almost all drive engineering products, such as torsionally stiff couplings, torque limiter couplings and clamping Systems.