Gear couplings are torsionally rigid and are capable of transmitting large amounts of power. They are engineered in two principal designs; flexible and flexible/rigid. The term “flexible” referring to torsionally rigid industrial couplings, indicates that they are able to compensate for specified amounts and types of misalignment. A flexible gear coupling uses two outer sleeves with an internal gear and two hubs with an external gear. This design tolerates all possible misalignments (angular, offset and combined) as well as significant axial thrust. Machines, seals, bearings, and shafts are protected from the additional forces caused by system misalignment compared to the performance of rigid shaft couplings.