Technical tables become more useful once every dimension is attached to a decision. On an NM coupling, D and D1 help describe the outside envelope and hub geometry, d max limits the specified bore capacity, L controls axial space, and S gives the model-specific separation value used during assembly.
d max is usually the first interface check.
Both shafts have to fit. If one exceeds the specified d max, the model is not a clean candidate even when its torque rating looks comfortable. Moving up a size requires a new envelope check because D and L also increase.
S belongs in installation, not only in the drawing.
Use the model’s S value when positioning the hubs. An arbitrary gap can change how the flexible ring sits and can reduce the value of the specified alignment limits. After tightening the machines, re-check the gap and alignment.
