The major classes of couplings are rigid couplings, flexible couplings, fluid couplings and magnetic couplings.

Rigid couplings do not support misalignment of the axes. In this group:

- Sleeve couplings: in this case the axes are connected by a cylindrical shaped piece cylindrical inner hole. Not allow shaft misalignment. Its main application is to link several axes forming one very long, since a so long could not be produced.

- Split sleeve couplings: is similar to above, but the sleeve is formed by a pair of parts, which are joined with screws. Unlike the earlier allow replacement without displacing the shafts.

- The plate flange couplings: is formed by a pair of axles forged plates. Then the plates are joined with tronillos and nuts.

Flexible couplings withstand some misalignment of the axes and also absorb sudden changes in power the transmit power.

One of the simplest types are the flange. Consists of a plate which is attached to each axis and then the periphery of the plates are joined together using a caucha rim, so that the power transmission is carried out through tire. Are also known as Periflex.

Another type is formed by two plates joined to the shafts and these plates joined together by screws, but tronillos have a rubber coating, so that power transmission is performed through these rubber bushings.

These couplings have seen that refer to axes that are collinear or at a small angle of misalignment, for larger angles of misalignment are used Cardan joints and constant velocity joints. The first has the disadvantage that the speed is not continuously transmitted error if address and resolve the latter.