This partial calculator reports only selected rope and throat dimensions. It does not estimate a stevedore knot's finished size, tail requirement, pull-through retention, strength or safety.
Partial · Selected Rope and Throat Dimension Ledger
Compare selected rope and throat dimensions without predicting knot size, retention or safety.
Equation Used
- Diameters are selected nominal values.
- No finished-knot multiplier is inferred.
- Rope construction, dressing, loading, tail, retention, strength and safety are excluded.
The figure is a diameter ledger, not a tied-knot geometry or pass/fail test.
Supported selected-dimension arithmetic
For selected rope diameter d and throat diameter D, nominal rope area is pi d squared over 4, circumference is pi d, diameter ratio is D/d and radial difference is (D-d)/2.
Use and boundary
Use only to compare selected nominal diameters. Knot fit and retention require a defined knot, rope construction, dressing, loading, tail, device geometry and tested acceptance criteria.
Dimension identities
area=pi d squared/4; circumference=pi d; ratio=D/d; radial difference=(D-d)/2.
Default example
For d=10 mm and D=24 mm, rope area is about 78.54 square millimetres, circumference is 31.42 mm, ratio is 2.4 and radial difference is 7 mm.
Unsupported knot claims removed
The former 3.0d, 2.2d and 6d multipliers and geometric jam verdict were not supported by controlled stevedore-knot tests.
Questions
Does positive radial difference prove retention?
No.
Does this specify a tail length?
No.
References
How actuator stroke affects Stevedore Knot Mechanism
With stevedore knot mechanism, the motion profile matters. A linear actuator gives direct extension and retraction, but the output linkage may still create non-linear speed, changing mechanical advantage, and end-of-travel loads.
For geared motion, review reduction ratio, back-driving, and output speed. The actuator gear train may add holding ability, but the surrounding mechanism still needs proper stops and alignment.
The mechanism may also change speed as the linkage angle changes. A constant actuator extension speed does not always create constant output speed, so timing should be checked at the actual output point.
- Map actuator stroke to the actual output travel before choosing a model.
- Check for binding, changing leverage, and peak load near the ends of travel.
- Decide whether timed motion is acceptable or position feedback is required.
For a FIRGELLI design review, calculate the load case with the FIRGELLI actuator force calculator and plan the switching or controller arrangement with the linear actuator wiring diagram generator. If an actuator or cylinder is already installed, the linear actuator replacement finder helps keep the comparison tied to real dimensions.
References & Further Reading
- Wikipedia contributors. Stevedore knot. Wikipedia
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