A(n)<u> Solid</u> coupling is used when it is necessary to extend the length of a shaft or to provide a means of disconnecting a shaft.
The basic function of all couplings is to transmit power, accommodate misalignment and compensate for axial movement (end movement of shafts). Sometimes, a coupling is asked to absorb shock or vibration. A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power.