The task of shaft couplings is to connect two shafts. They transmit rotational motion from one axis to another that are aligned or angled with each other.
We know different types of shaft couplings.
Flexible: These should compensate for angle and misalignment.
Rigid: connect two axles with a rigid/rigid coupling
Elastic: consist wholly or partly of elastic material. This allows them to absorb vibrations.
Torsion-free: for transmitting a torque without or with limited angular rotation.