Can every coupling misalignment limit be used at its maximum simultaneously?

The short answer

Not necessarily. Catalogue displacement maxima may apply separately or under a defined combination rule. Simultaneously using maximum angular, radial and axial movement can exceed a coupling’s permitted deformation. A small-wind drivetrain assessment needs the manufacturer’s combined-displacement criteria, not three independent pass marks.

Identify what each maximum assumes

A table can state values for a specific speed, torque, temperature and coupling material. It may assume another displacement is absent or reduced. The limiting strain occurs in the same flexible components, so independent headline maxima do not prove that all can coexist. Read the explanatory notes and combination diagram rather than extract only the largest values into a bid comparison.

Evaluate the actual combination

Retain the predicted displacements as a set for each operating case. A cold assembly with one offset and a hot assembly with another are not necessarily one simultaneous worst case, but an assumed separation needs evidence. Conversely, small individual percentages can combine unfavorably under the maker’s method. KTR documentation provides product-specific combined-displacement guidance; it must not be treated as a universal formula for all couplings.

Request the governing case and method

Ask the supplier to show how the actual angular, radial and axial values satisfy the selected coupling’s combined limit at relevant duty conditions. Keep the input convention and instruction issue with the result. No MARSTON coupling allowances are established here. If the combination is outside the documented envelope, refer the arrangement to the designer rather than redistribute an arbitrary “total misalignment budget” or assume a larger coupling automatically permits every movement. Keep simultaneous displacement cases separate from unrelated independent extremes. The manufacturer’s combination method needs a coherent physical state; combining impossible extremes can mislead just as much as ignoring real concurrent motion.