This partial calculator is explicitly narrowed to a selected dimension-ratio ledger. It does not reconstruct the named slotted-arm mechanism because crank center, crank-pin engagement, lever pivot, output joint, slider guide and connecting geometry are not jointly defined.
Partial · Selected Arm-Ratio Ledger
Compare selected lengths and a valid in-slot pin fraction without inventing slotted-arm motion.
Equation Used
- Input reference length and slot length are positive.
- Output-pin fraction is between zero and one.
- Selected length ratio is not labeled as mechanical advantage.
- Crank, slot engagement, pivots, connecting links, slider guide, position, stroke, speed, force, collision and safety are excluded.
The secondary figure is a dimension ledger, not a connected slotted-arm mechanism.
Supported selected-dimension relationships
Choose an input reference length Lin, a slot length Lslot and a valid output-pin fraction f between zero and one. Selected output distance is Lout=f Lslot, the selected length ratio is Lout/Lin, used slot share is 100f and remaining slot length is Lslot-Lout.
These are dimension identities only, not a lever-motion or output-stroke solution.
Use and boundary
Use the ledger to compare selected lengths and a valid pin position within a slot. Do not use it to predict stroke, rectilinear position, speed, force or linkage closure.
Selected ratio identities
Lout=f Lslot; ratio=Lout/Lin; slot used=100f; remaining=Lslot-Lout.
Default selected-value example
For Lin=80 mm, Lslot=200 mm and f=0.75, selected output distance is 150 mm, selected length ratio is 1.875, 75% of the slot is used and 50 mm remains.
Unsupported kinematic claims removed
The former model called 2r(Lout/Lin) an output stroke and derived a harmonic peak speed although the linkage was not closed. Crank radius and speed were removed, and output-pin position is now guaranteed to lie within the selected slot.
Questions
Is the selected ratio a mechanical advantage?
No. It is only a length ratio.
Does the calculator predict stroke?
No.
Can the selected pin lie beyond the slot?
No. The fraction is limited to one.
References
References & Further Reading
- Wikipedia contributors. Linkage (mechanical). Wikipedia
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