A gear coupling transmits torque through toothed hubs and mating sleeves. Crowned hub teeth accommodate limited angular movement at each mesh. A double-engagement arrangement has two flexible connections, allowing shafts to operate with specified angular or parallel misalignment. The calculator compares entered angles with chosen thresholds and converts an entered crown-drop dimension.
Gear Coupling Interactive Calculator
Compare an entered per-mesh angular displacement with two user-entered angle thresholds and convert an entered crown-drop dimension from inches to thousandths while a schematic double-engagement coupling rocks at two flex planes.
Equation Used
- Two equal flex-plane angles are shown in opposite directions for the displayed total span.
- Rated and seal-warning angles are supplied by the user from an applicable source.
- Entered crown drop is converted only; no tooth geometry is derived.
- No torque, tooth contact, backlash, lubrication, temperature, seal, load, fatigue or life model.
User-defined comparison arithmetic only. The rated and seal-warning angles are not supplied by this calculator and the resulting percentages do not predict tooth loading, seal failure or service life. Crown drop is only a unit conversion.
Crowned hub teeth and two flex planes
Lovejoy's manufacturer literature describes external hub teeth meshing with sleeve teeth and explains that crowning broadens contact under misalignment compared with straight hub teeth. Its double-engagement products use two gear meshes, or flex planes, to accommodate angular and parallel misalignment.
The animation marks the two flexible connections and shows prescribed rocking. It does not draw or calculate the loaded tooth contact, and the rocking is not a simulation of a rotating coupling under load.
Comparison use
The calculator can compare a measured or specified per-mesh angle with limits the user has obtained for an identified coupling and can illustrate two flex planes. It cannot select a coupling or establish allowable misalignment; those values depend on the exact manufacturer, series, size, speed, torque, lubricant and configuration.
User-entered angle comparisons
Angle utilization is entered angle divided by entered rated angle. The seal-threshold index is entered angle divided by entered seal-warning angle. Both are dimensionless comparisons, not predictions. The displayed 2theta span assumes two equal flex-plane angles oriented oppositely. Crown drop in thousandths is simply the entered inches multiplied by 1000.
Example: comparing entered angles
For a per-mesh angle of 1.5°, a chosen Rated angle of 1.5° and Seal warning of 0.75°, the outputs are 100% Angle Use and 200% Seal Index. These percentages compare numbers you supplied; they do not establish that a particular coupling is within its rating or that a seal has failed.
Total Swing is 3.0° for two equal 1.5° angles in opposite directions. Crown drop of 0.001 in converts to 1.0 thou, where one thou is one thousandth of an inch.
At zero angle, both percentages and Total Swing become zero. Crown Drop remains the unit conversion of its separate input. Doubling either threshold halves its associated percentage without changing the drawn angle.
Scope and limitations
Actual gear-coupling selection and alignment require manufacturer catalog data for the exact coupling, torque and service factor, speed, bore and fit, tooth geometry, backlash, lubrication, balance, seal type, axial travel, combined angular/parallel offset and installation procedure. None are calculated here.
Frequently asked questions
Does 100% Angle Use certify acceptable alignment?
No. It only means that the entered angle equals the entered Rated angle. Check the actual coupling manufacturer’s limits and how they apply to its configuration and operating conditions.
Does Seal Index predict leakage?
No. It divides one entered angle by another and has no model of the seal.
Why does Crown drop not change the other results?
It is an independent unit conversion from inches to thousandths. Tooth contact, load capacity and crowning geometry are not calculated.
What does Total Swing represent?
It is twice the entered per-mesh angle, representing two equal angles directed oppositely. It is not a universal allowance for installed shaft misalignment.
Manufacturer technical references
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