A diaphragm coupling transfers torque through a continuous flexible annulus between an inner attachment and an outer attachment. This calculator compares bore-side and rim-side thickness and an entered shaft angle. The animation follows the continuous annulus between its inner hub and outer flange as the shafts rotate.
Diaphragm Coupling Interactive Calculator
Compare diaphragm thicknesses and a small shaft angle. The continuous annulus connects inner and outer attachments; the separate angle detail is enlarged 50× for visibility.
Equation Used
- Single annular diaphragm element.
- Smooth compatible display geometry, not elastic plate analysis.
- 0.25° is an example, not a limit.
- Linear radial thickness comparison.
Profile and angle comparisons only. No torque, stiffness, stress or allowable-angle rating.
A continuous annulus joins two rotating attachments
The oblique view shows the inner hub and shaft, flexible annular plate, outer clamp and backing flange, and the other shaft. The casing bridge is cut away to expose the diaphragm. These are connected components, not alternating short links on a disc-coupling bolt circle.
The inner and outer attachments rotate at the same nominal angular speed. A gold material witness mark follows one radius through a prescribed smooth flexed surface. The shaft axes stay at the entered angle rather than rocking back and forth.
The main view uses the actual angle. A separate detail enlarges angular displacement 50 times, with both actual and enlarged values shown. This makes sub-degree adjustments visible without presenting the enlarged angle as real operation.
Compare profile dimensions without claiming a rating
Enter bore-side thickness, rim-side thickness and angular misalignment to compare the profile dimensions and shaft angle. Thickness changes alter the separate profile drawing, while angle changes alter the attachment planes and enlarged angle detail.
The radial profile is a linear interpolation between the entered thicknesses. Actual contoured diaphragms are designed for their stress and flexibility requirements; a straight taper and its thickness ratio are not a substitute for that design.
Thickness and angle comparisons
For bore thickness tb and rim thickness tr, profile ratio is tb/tr, thickness difference is tb−tr, and rim percentage is 100tr/tb. The example-angle ratio is θ/0.25°.
The separate section uses normalized radial coordinate u from zero at the bore side to one at the rim side, with t(u)=tb+(tr−tb)u. No radial span or torque is inferred from those thickness values.
The annular illustration smoothly connects an inner plane to an outer plane at θ. Its displacement interpolation has matching slopes at both attachments. That is compatible display geometry, not a solved elastic plate, stress distribution or fatigue calculation.
A 6 mm to 1.5 mm thickness comparison
The 6 mm and 1.5 mm example gives a 4:1 thickness ratio, a 4.5 mm difference and a rim thickness equal to 25% of the bore-side thickness.
The entered 0.25° angle equals the illustrative reference angle, so its comparison is 1×. The enlarged detail shows 12.5° because of its explicitly stated 50× angular enlargement. The main coupling remains at 0.25°.
Changing angle does not alter the thickness ratios, and changing thickness does not alter the entered angle. Those independent results are intentional.
One element does not define a complete coupling selection
The view shows one flexing element under angular misalignment. General parallel shaft offset requires an appropriate multi-element arrangement, commonly two flexing elements separated by a spacer.
The model does not calculate transmitted torque, torsional or bending stiffness, bearing reactions, stress, fatigue, axial travel or allowable speed. Neither the input range nor the 0.25° example is an allowable-misalignment specification.
A diaphragm transfers torque through a continuous annulus. A disc pack uses separate flexible plates, while a Schmidt coupling uses articulated links; their construction and selection methods differ.
Diaphragm-coupling questions
Why does the shaft angle look small?
The input range is at most one degree and the main view respects that. The separate enlarged detail is provided for readability.
Does the gold line represent a crack or a separate spoke?
No. It is a witness mark on a continuous diaphragm, used to show material rotation.
Is the profile ratio a torque rating?
No. It compares two thickness measurements only.
Is the shown flexing shape an elastic solution?
No. It is a smooth compatible construction between the two attachment planes; material properties and loads are not inputs.
Reference
Ameridrives: Disc vs Diaphragm Couplings, Jon R. Mancuso — continuous inner-to-outer attachment construction, distinction from disc couplings, and diaphragm profile/design differences. The comparative dimensions in this calculator are not manufacturer ratings.
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