A jaw coupling is a type of general purpose power transmission coupling that also can be used in motion control (servo) applications. It is designed to transmit torque (by linking two shafts) while damping system vibrations and accommodating misalignment, which protects other elements from damage.
Jaw Couplings are among the first and still most widely used elastomer couplings in the globe due to their inherent simplicity. Two identical hubs with 3 face lugs are linked through a celebrity shaped element, sometimes referred to as an insert or spider. The 3 piece design makes them easy to work with and well-known on applications such as pumps, enthusiasts, blowers and compressors.
Jaw Couplings need no lubrication and offer high dependability for light to medium duty applications with good alignment of equipment and no requirement for torsional dampening.
In regular operating conditions there is no metal to metallic contact so the life of the hubs is practically indefinite. However, in a catastrophic failing of the element the load would be carried by the hubs offering a amount of failure protection. Jaw couplings are resistant to essential oil, dirt, moisture and grease.
Specific element materials are available to achieve optimum performance for the functioning 
conditions.
The standard element material is NBR (N)-‘Synthetic Rubber’. It really is highly flexible, essential oil resistant and the torsionally softest of the component options. It has a heat range operating range suitable for most commercial applications and allows for up to 1 1 degree misalignment capacity of the connected shafts. NBR may be the most economically costed option.