Brown movement 63 uses pins on a continuously rotating disk to lift a spring-carried drop and its attached pawl. The pawl is released first into the next star-wheel space; release of the drop then produces the rapid indexed advance.
Count the indexed advances
The calculator assumes one successful star-wheel step for each passing driver pin. It compares counts and average event frequency; it does not select a drive or predict whether the pawl will engage.
Jumping Intermittent Rotary Interactive Calculator
Compare exact one-space indexing arithmetic for entered star-wheel spaces, equally spaced lifting pins and driver speed.
Equation Used
- N and M are positive integers.
- Each equally spaced driver pin produces exactly one successful release and one-space advance.
- Driver speed is uniform.
- No missed events, bounce, coast, backlash, interference, impact, spring-force or wear model.
The calculation assumes one successful star-wheel advance per release event; it does not predict contact, spring or impact behavior.
Two-stage release sequence
The right driver disk rotates continuously. Each projecting pin lifts the long drop and attached pawl. The geometry releases the pawl before the drop, placing the pawl in the next star-wheel space. The driver pin then clears the drop; spring action brings the drop down and the drop pin acts on the pawl, producing the visible jump.
The animation separates assigned lift, release, advance and dwell phases. The drawn pawl points away from the star wheel, and the driver pins do not reach the drop, so the visible motion should not be read as a functioning contact mechanism.
Count release events
For N equal star-wheel spaces, one successful event advances 360/N degrees. M equally spaced pins produce M release events per driver revolution, so ideal output is M/N revolution per driver revolution. Driver rpm sets event frequency but not angular advance per event.
Indexing arithmetic
Step angle is 360°/N. Events per driver revolution equal M. Ideal output revolutions per driver revolution are M/N, and event frequency is Mn/60 hertz at n rpm. These identities do not establish that a proposed physical tooth, pin, pawl or spring geometry will execute every event.
Example
A 10-space star wheel with three equally spaced driver pins advances 36° at each successful release. One driver revolution produces three events and 0.3 output revolution. At 60 rpm, event frequency is 3 Hz.
Scope and limits
Brown describes a separate driver disk, lifting pins, spring-carried drop, attached pawl and star wheel. The pawl is released before the drop. The current animation assigns that sequence mathematically; it does not solve the contacting geometry.
Successful engagement depends on component profiles, pivot positions, clearances, spring behavior and impact loads. These are not inputs to the counting equations. The calculator cannot establish reliable indexing or a maximum operating speed.
Questions
Is this a simple pawl riding over ratchet teeth?
No. Brown's movement uses a separate pin-lifted drop and attached pawl with staged release.
Do more driver pins change step angle?
No. Star-wheel space count sets step angle; pin count sets events per driver revolution.
Does the calculator prove reliable counting?
No. It assumes one successful advance per event.
Historical source
Henry T. Brown, Five Hundred and Seven Mechanical Movements, movement 63: jumping or intermittent rotary motion for meters and revolution counters, including the pin-lifted drop, attached pawl, staged escape and star-wheel advance.
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