Die Casting Though one might not think about gears as being flexible, gear couplings are extremely much considered to be a flexible coupling. A equipment coupling is certainly a mechanical device designed to transmit torque between two shafts that are not collinear. The coupling typically contains two flexible joints, one set to each shaft. These joints tend to be connected by a third shaft called the spindle.
Each joint generally includes a 1:1 gear ratio internal/external gear set. 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 altered profiles. They are known as gears due to the relatively huge size of the 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 gear couplings contain short sleeves encircled by a perpendicular flange. One sleeve can be positioned on each shaft therefore the two flanges line up in person. A number of screws or bolts in the flanges keep 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, but they can also be made of Nylon.
Single joint equipment couplings are accustomed to connect two nominally coaxial shafts. In this application these devices is named a gear-type flexible, or flexible coupling. The single joint permits small misalignments such as for example installation errors and adjustments in shaft alignment because of operating circumstances. These kinds of equipment couplings are usually limited to angular misalignments of 1/4 to 1/2°.