Two moving pawls alternately drive a ratchet wheel as the lever rocks. In the ideal arrangement shown, each half-stroke advances one tooth, giving two tooth advances per complete lever cycle.
Two-Pawl Ideal Indexing Calculator
Enter complete lever cycles per minute and ratchet tooth count. The worksheet reports the ideal half-stroke event rate, tooth rate, wheel speed and angular advance per complete lever cycle. It does not rate engagement, force, wear or permissible swing.
Equation Used
- Each of the two moving pawls advances exactly one tooth on its driving half-stroke.
- The returning pawl rides over the teeth and reseats ideally.
- Tooth count is integral and the wheel has uniform pitch.
- Loads, spring force, backlash, missed engagement, wear, allowable swing and strength are excluded.
With one tooth advanced on each half-stroke, the tooth-advance rate is twice the complete lever-cycle rate. Dividing by tooth count gives ideal wheel rpm.
One driving pawl on each half-stroke
The two pawls share a moving lever pin and reach opposite sides of the ratchet. As the lever rocks, one pawl drives a tooth while the other returns over the tooth ramps; their roles exchange on the return half-stroke.
The animation preserves fixed pawl lengths and connected lever geometry. Ideal seating is declared rather than predicted.
An ideal indexing-rate worksheet
Use the calculator to translate an entered complete-cycle rate and tooth count into ideal wheel motion. Real devices require tooth, spring, backlash, load and wear design.
Two advances per complete cycle
Indexing example
At 90 complete lever cycles/min with a 36-tooth wheel, the ideal mechanism makes 180 driving half-strokes/min, advances 180 teeth/min, turns at 5.00 rpm and advances 20.0 degrees per complete lever cycle.
What determines reliable engagement
Engagement and required swing depend on the actual tooth and pawl geometry, spring forces, clearances and load. The two-advances-per-cycle relationship assumes successful engagement on every half-stroke.
Two-pawl indexing questions
Does every real cycle advance two teeth?
No; that is the explicitly idealized arrangement modeled here.
Does this calculate required handle swing?
No.
Does wheel speed rate load capacity?
No.
Ratchet references
- US5782147A, Ratchet wrench having two-pawl action: two pawls work conjointly and alternately engage a ratchet gear, reducing backswing.
- US9038507B2, Dual pawl ratchet mechanism: first and second pawls selectively engage a ratchet gear.
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