Though one might not think about gears to be flexible, gear Taper Lock Pulley couplings are extremely much considered to be a flexible coupling. A equipment coupling is usually a mechanical device made to transmit torque between two shafts that are 
not collinear. The coupling typically contains two flexible joints, one set to each shaft. These joints are often connected by a third shaft called the spindle.
Each joint generally contains a 1:1 gear ratio internal/external gear pair. The tooth flanks and outer size of the exterior equipment 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. Equipment couplings are usually limited by 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 certainly positioned 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 gear couplings feature shaft ends coupled collectively and abutted against one another, which are then enveloped by a sleeve. Generally, these sleeves are made of metal, but they may also be made of Nylon.
Single joint equipment couplings are used to connect two nominally coaxial shafts. In this application these devices is called a gear-type versatile, or versatile coupling. The one joint allows for minimal misalignments such as installation errors 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°.