Mechanism Actuator Sizing — validation & limitations

What this calculator checks and the method behind each result, the independent reference cases its engine is tested against, and what it does not check. Use it to decide how far you can rely on a result.

Open the Mechanism Actuator Sizing

What it calculates

Standard / method: Planar mechanism statics · F = p·A on ISO 15552 cylinder sizes · projected bush contact check

The kinematic and force chain is exact planar geometry — each actuator's torque uses its true line of action (cap pivot → rod-end) recomputed at every angle — with pneumatic cylinder push/annulus areas (F = p·A, ISO 15552 cylinder sizes) and an optional projected bush contact-pressure check. The load model (friction / inertia / worst-case gravity / process torque) is a documented, conservative engineering estimate.

Engineering estimate — this tool uses an accepted simplified model rather than one citable governing standard. Use it for preliminary sizing and verify the final design against manufacturer data or a qualified engineer.

Exact actuator torque T = F·d(θ) with the moment arm d taken from the true cap→rod-end line of action at every angle — not the perpendicular-arm shortcut that overstated single-actuator SF ~2.9× on the validated mechanism
Two topologies: direct lever (rod-end on the output link — gates, lids, tilt tables, dampers) and slot-coupled bell-crank (actuators drive a crank; a pin on the output link rides its slot)
Slot-coupling kinematics solved by continuation Newton iteration and validated against a physical Autodesk Inventor assembly (pipe-diverter valve) to a maximum error of 0.04° at 4 measured poses
Dead-point detection — flags any pose where the drive path collapses (moment arm below 2 % of its own radius, floor 0.5 mm, or a sign change) and the mechanism cannot be driven through
1-vs-2-actuator verdicts: minimum safety factor over the full sweep for each actuator alone and for all actuators together, with the worst-case angle reported
Pneumatic cylinder force F = p·A (ISO 15552 cylinder sizes): push p·(π/4)·D², pull on the rod-side annulus, automatic worst-stroke selection for reversing loads, and a delivery derate η for regulator droop and seal friction
Conservative load bound: constant friction torque + motion-profile-scaled inertia I·α (trapezoidal default — triangular is the theoretical minimum peak acceleration) + a proven worst-case gravity bound m·g·r_cg (vertical swing plane) + process torque — flagged as an engineering estimate
Slot travel and utilisation check with tolerance-margin warnings, plus an optional projected bronze-bush contact-pressure check at the slot pin (bush OD against the slot flank)

Validation evidence — independent reference cases (0)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

No independent reference case is registered for this tool yet. Its engine is covered by the regression suite, but no published worked example has been reproduced end to end.

Limitations

Not checked by this tool

Actuator piston-rod buckling on the push stroke — Check buckling against the cylinder maker's chart at the extended pin-to-pin length with the maximum push force (catalog p·A for a cylinder) and the mounting style — or use /pneumatics
Clevis / pin / rod-eye strength — Size the clevis pins for the maximum push force (catalog p·A for a cylinder)
Bush bore against the pin — Only the bush outside diameter on the slot flank is checked; the bore carries the same force over a smaller area
Strength and stiffness of the links, crank arm and brackets — Not computed; size them for the peak actuator force by hand or FEA
Pivot pin shear and pivot bearing life — Size the pivot pins and bearings for the joint reactions (/bearings for rolling pivots)
End-of-stroke impact and cylinder cushioning — Check the moving mass and speed on the cylinder maker's cushioning diagram

Results are engineering calculations for qualified users — see the disclaimer. Other tools: all validation pages · standards reference · symbols glossary.