Though one may not think about gears to be versatile, gear couplings are very much regarded as a versatile coupling. A equipment coupling is normally a mechanical device made 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 linked by a third shaft called the spindle.

Each joint generally contains a 1:1 equipment ratio internal/external gear pair. The tooth flanks and external diameter of the exterior equipment are crowned to allow for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with modified profiles. They are called gears due to the relatively large size of one’s teeth. Gear couplings are usually limited to angular misalignments of 4 to 5°.

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

Single joint equipment couplings are accustomed to connect two nominally coaxial shafts. In this application the device is called a gear-type flexible, or flexible coupling. The single joint permits minimal misalignments such as installation errors and adjustments in shaft alignment because of operating conditions. These types of gear couplings are usually limited to angular misalignments of 1/4 to 1/2°.