A flexible shaft coupling joins rotating shafts while allowing limited alignment error according to its specific design and manufacturer data. This calculator compares selected parallel and angular measurements with selected reference values; it does not rate or select a coupling.
Flexible Shaft-Coupling Alignment Comparison
Compare selected shaft alignment measurements independently with selected reference values.
Equation Used
- Measurements and references are nonnegative and use matching units.
- Parallel and angular comparisons are reported independently.
- The angular deflection in the drawing is magnified and labeled.
- Product-specific combined envelopes, loads, speed, life, heat and safety are excluded.
Reference values are user-selected comparison denominators, not verified limits for a particular coupling.
Parallel and angular alignment coordinates
Manufacturer instructions distinguish parallel offset between shaft centerlines from angular misalignment measured across hub faces. The animation uses a metal-bellows coupling as an example: two rigid hubs joined by a corrugated flexible center. Both hubs turn together, while the bellows bends between the shaft axes. Angular deflection is magnified for legibility.
What the calculator determines
Select measured parallel offset e and angular error α plus comparison references eref and αref. The calculator reports the two independent normalized ratios and the signed differences between each reference and measurement.
No combined capacity or overload result is inferred.
Independent comparison identities
Re = 100e/eref; Rα = 100α/αref; Δe = eref − e; Δα = αref − α.
Selected-input arithmetic
For e = 0.10 mm versus 0.40 mm and α = 0° versus 1°, the independent ratios are 25% and 0%, with signed differences 0.30 mm and 1.00°.
Alignment comparisons and coupling selection
Actual allowable parallel/angular combinations are product-, size-, speed-, load-, spacing-, material- and installation-specific. Manufacturer guidance may prohibit operating at both maxima or provide a product-specific combined envelope. Selected references here are not catalog limits, and the larger ratio is not a capacity rating.
Questions
Does 100% mean a coupling is safe?
No.
Can both selected references be used simultaneously?
This calculator does not establish that.
Does the drawing reproduce jaw contact stress?
No. The illustration shows a bellows coupling and does not calculate contact stress or metal strain.
References & Further Reading
R+W metal-bellows coupling installation instructions: hub construction and shaft misalignment.
- Wikipedia contributors. Coupling. Wikipedia
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