What factors are considered in shaft coupling design for torque transmission?

Key factors include: design torque (with service factors 1.5-3 for shock loads), shaft diameter and fit (interference or keyed), coupling type selection (rigid, flexible, or fluid), bolt sizing for flange couplings (τ = 16T/(πd³n × D) where D is bolt circle diameter), key design for shear and crushing, and alignment requirements. Misalignment causes additional stresses and vibration.