We use four other types of couplings extensively in naval equipment:

1. The fixed (sliding lug) coupling, which is nonadjustable; it does allow for a small amount of misalignment in shafting (fig. 11-17).

2. The flexible coupling (fig. 11-18), which connects two shafts by a metal disk. Two coupling hubs,

each splined to its respective shaft, are bolted to the metal disk. The flexible coupling provides a small amount of flexibility to allow for a slight axial misalignment of the shafts.

3. The adjustable (vernier) coupling, which provides a means of finely adjusting the relationship of two interconnected rotating shafts (fig. 11-19). Loosening a clamping bolt and turning an adjusting worm allows one shaft to rotate while the other remains stationary. After attaining the proper relationship, you retighten the clamping bolt to lock the shafts together again.

4. The adjustable flexible (vernier) coupling (fig. 11-20), which is a combination of the flexible disk coupling and the adjustable (vernier) coupling.