How small can the MD be made? What is the limiting factor?
The MD typically saves space in the axial dimension. The thinnest design to date is an 11mm wide, 600 ft-lb MD used in an automotive transmission. Saving space in the radial dimension depends on the relationship between the OD and ID. If the difference between the radius of the OD and ID is less than 16 mm then there isn’t usually enough space for the strut.