Rigid Couplings

A rigid coupling is one that does not allow axial or radial motion between the driving and driven shafts. As shown in Fig. 3.130, a rigid coupling consists of two flanges, one mounted on each shaft. Rigid couplings require exact alignment between shafts otherwise considerable wear on the bearings and seals will occur. They serve primarily to transmit energy from the drive side to the driven side of a rotary system, and secondary functions include compensating for misalignment or reducing vibration.A gear coupling is a mechanical device for transmitting torque between two shafts that are not collinear. It consists of a flexible joint fixed to each shaft. The two joints are connected by a third shaft, called the spindle. Each joint consists of a 1:1 gear ratio internal/external gear pair.Rigid couplings are used for shafts having no misalignment. Since these couplings cannot absorb any misalignment the shafts to be connected by a rigid coupling .Rigid couplings are used to connect two shafts that are aligned with each other. Flexible couplings are used to connect two shafts that are not aligned with each other.Couplings fall into two main categories: Material Flexing and Mechanical Flexing. The material flexible types obtain their flexibility from stretching or compressing a resilient material, such as rubber, or from the flexing of thin metallic discs or grid.