Though one might not think of gears as being flexible, gear couplings are very much regarded as a flexible coupling. A equipment coupling is a mechanical gadget designed to transmit torque between two shafts that aren’t collinear. The coupling typically includes two flexible joints, one fixed to each shaft. These joints are often connected by a third shaft known as the spindle.

Each joint generally contains a 1:1 gear ratio internal/external gear pair. The tooth flanks and external size of the exterior gear are crowned to allow for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with altered profiles. They are known as gears due to the relatively large size of the teeth. Gear couplings are generally limited to angular Shaft Collar misalignments of 4 to 5°.

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

Single joint gear couplings are used to connect two nominally coaxial shafts. In this application these devices is named a gear-type flexible, or versatile coupling. The one joint allows for minimal misalignments such as installation mistakes and changes in shaft alignment due to operating conditions. These types of equipment couplings are generally limited to angular misalignments of 1/4 to 1/2°.