Geneva indexing mechanism calculator

External Geneva indexing and dwell fractions for a uniform driver.

linkages-geneva.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	indexAnglerad	engagement	cycles	dwells
	1.0472	0.333333	1	0.666667
	1.25664	0.3	1	0.7

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

positive dwell0.67 s✓ passes

BASELINE INPUTS

slots6 speed60 rpm

CALCULATED

indexAngle1.0472 rad

engagement0.33333

cycle1 s

dwell0.66667 s

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Geneva indexing mechanism
# Scope: External Geneva indexing and dwell fractions for a uniform driver.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

slots = 6
speed = 60 rpm

indexAngle := 2*pi/slots [rad]
engagement := (pi-2*pi/slots)/(2*pi)
cycle := 2*pi/speed [s]
dwell := cycle*(1-engagement) [s]

check positive dwell: dwell > 0 s

scenario alternative: slots = 5

Calculated from your source · not saved

Baseline · Baseline

positive dwell0.67 s ✓ passes

alternative · alternative

positive dwell0.70 s ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

index angle: indexAngle = 2*pi/slots [rad]
engagement: engagement = (pi-2*pi/slots)/(2*pi)
cycle: cycle = 2*pi/speed [s]
dwell: dwell = cycle*(1-engagement) [s]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

slots: 6
speed: 60 rpm

Calculated

index angle: 1.0472 rad
engagement: 0.333333
cycle: 1 s
dwell: 0.666667 s

Assumptions and limits

External Geneva indexing and dwell fractions for a uniform driver.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Geneva indexing mechanism. Inputs: slot count; driver speed; pin geometry. Outputs: index angle; dwell; engagement motion. Model scope: Planar rigid-link geometry with explicit joints and branches. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: slot count, driver speed, pin geometry
Outputs: index angle, dwell, engagement motion
Modes: calculate, compare, sweep
Drawing: Interactive linkage

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS