Though one may not think of gears to be flexible, gear couplings are extremely much regarded as a flexible coupling. A gear coupling can be a mechanical device designed to transmit torque between two shafts that are not collinear. The coupling typically includes two versatile joints, one fixed to each shaft. These joints tend to be connected by a third shaft known as the spindle.

Each joint generally consists of a 1:1 equipment ratio internal/external gear pair. The tooth flanks and outer diameter of the external equipment are crowned to permit for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with modified profiles. They are known as gears due to the relatively huge size of the teeth. Gear couplings are generally limited to angular misalignments of 4 to 5°.

Equipment couplings ordinarily can be found in two variations, flanged sleeve and continuous sleeve. Flanged equipment couplings consist of short sleeves surrounded by a perpendicular flange. One sleeve is placed on each shaft so the two flanges fall into line in person. A series of screws or bolts in the flanges hold them jointly. Continuous sleeve equipment couplings feature shaft ends coupled together and abutted against each other, which are then enveloped by a sleeve. Generally, these sleeves are constructed with metal, but they may also be manufactured from Nylon.

Single joint equipment couplings are used to connect two nominally coaxial shafts. In this application these devices is called a gear-type flexible, or flexible coupling. The single joint allows for minor misalignments such as installation mistakes and adjustments in shaft alignment due to operating circumstances. These kinds of gear couplings are usually limited to angular misalignments of 1/4 to 1/2°.