The coupling is a part of a drivetrain designed to connect the shafts and transmit torque without changing its direction. Couplings consist of an active and a passive member located on the pivots of devices being coupled and a connector (or its several parts) enabling the entire propulsion system to be assembled. The connector determines how the torque is transmitted and it characterizes the coupling and its properties.
These components can be manufactured in various forms and variations (e.g. with a brake drum or a brake disc) to suit the user's needs.