Though one might not think about gears as being versatile, gear couplings are extremely much considered to be a flexible coupling. A equipment coupling is a mechanical gadget made to transmit torque between two shafts that are not collinear. The coupling typically consists of 
two flexible joints, one fixed 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/exterior gear pair. The tooth flanks and external diameter of the exterior gear are crowned to allow for angular displacement between the two gears. Mechanically, the gears are equivalent to rotating splines with modified profiles. They are known as gears due to the relatively large size of the teeth. Gear 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 consist of short sleeves surrounded by a perpendicular flange. One sleeve can be positioned on each shaft therefore the two flanges line up face to face. A series of screws or bolts in the flanges hold them together. 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 constructed with metal, however they can also be made of Nylon.
Single joint gear couplings are accustomed to connect two nominally coaxial shafts. In this application the device is named a gear-type versatile, or versatile coupling. The single joint permits small misalignments such as installation mistakes and changes in shaft Oil-free Air Compressors alignment due to operating conditions. These types of equipment couplings are usually limited to angular misalignments of 1/4 to 1/2°.