Though one may not think about gears as being versatile, gear couplings are very much regarded as a versatile coupling. A gear coupling can be a mechanical device made to 
transmit torque between two shafts that aren’t collinear. The coupling typically contains two versatile joints, one set 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 set. The tooth flanks and external size of the exterior gear are crowned to permit for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with altered profiles. They are known as gears because of the relatively huge size of one’s teeth. Gear couplings are generally limited by angular misalignments of 4 to 5°.
Equipment couplings ordinarily can be found in two variations, flanged sleeve and continuous sleeve. Flanged gear couplings contain short sleeves surrounded by a perpendicular flange. One sleeve can be positioned on each shaft so the two flanges fall into line in person. A number of screws or bolts in the flanges hold them jointly. Continuous sleeve equipment couplings feature shaft ends coupled jointly and abutted against each other, which are then enveloped by a sleeve. Generally, these sleeves are made from metal, however they can also be made of Nylon.
Single joint gear couplings are accustomed to connect two nominally coaxial shafts. In this application these devices is named a gear-type flexible, or flexible coupling. The solitary joint permits minimal 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°.