This calculator compares entered torque with an entered coupling rating and expresses entered angular and parallel misalignment relative to two stated reference denominators. It does not select or approve a jaw coupling.
Jaw Coupling Interactive Calculator
Explore torque/rating arithmetic, signed torque margin and misalignment ratios relative to 1 degree and 0.4 mm references.
Equation Used
- Load and rating use the same torque units and basis.
- Entered rating is user-supplied and already appropriate for the exact selected coupling and duty if used beyond arithmetic exploration.
- One degree and 0.4 mm are explicit reference denominators, not asserted catalog limits.
- No speed, power conversion, starting/peak/reversing torque, service factor, temperature/material derating, axial displacement, combined misalignment interaction, spider stiffness/stress/heat/life, hub/shaft/key/clamp strength, critical speed, torsional vibration, alignment growth, guarding or safety model.
The entered rated torque must come from current manufacturer data for the exact hub size, spider material/hardness, temperature, speed and duty. The 1 degree and 0.4 mm values are comparison denominators only—not universal allowable limits.
Hub–spider–hub torque path
Interleaved hub jaws transmit torque through an elastomer insert loaded mainly in compression. The exploded view exposes the two hub bodies, their bores and axial jaws, and the connected spider between them. The transverse section below shows the alternating jaws around the assembled insert. The aligned parts rotate together. Entered offset and angle affect their numeric comparisons but do not deform the drawing.
Contact deformation, load sharing and allowable combined misalignment are not calculated.
Use as an entered-data comparison
The calculator can divide load torque by a rating the user has already verified and compare measurements with stated reference denominators. It cannot choose a series, size, bore, hub attachment or spider.
Ratios and arithmetic margin
Torque ratio is 100T/Trated, and arithmetic margin is Trated−T. The angle and offset tiles divide by 1 degree and 0.4 mm solely to create reference ratios. A result below 100% does not prove acceptability, because allowable values are product- and operating-condition-specific and may interact.
Arithmetic example
For entered load 18 N·m and entered rating 18 N·m, torque/rating is 100% and arithmetic margin is 0 N·m. Entered angle 1 degree and offset 0.4 mm each equal 100% of their stated reference denominators. None of those results is a selection approval.
Using an actual coupling rating
A catalog rating applies to a particular coupling size, spider and operating conditions. Temperature, speed, duty and combined misalignment can change the permitted load. Use the manufacturer’s selection procedure for that exact product; the simple ratios here do not perform those corrections.
Questions
Does 100% angle or offset mean the coupling is at its limit?
No. Those are ratios to stated reference denominators only.
Can I enter any catalog torque?
Only if its rating basis matches the exact spider, size and duty being compared.
Does positive arithmetic margin include shock or temperature?
No. No service or derating factors are calculated.
Further reading
KTR, ROTEX CF jaw coupling: manufacturer explanation of the two hubs and elastomer spider, including compressive loading of the insert. The product has its own technical data; the calculator’s reference denominators are not ROTEX ratings.
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