Drive geometry & speed
—
Preferred: z₁ ≥ 17
—
Max z₂ ≈ 120
mm
Recom.: 30–50× pitch
rpm
Results
| Parameter | Value | Unit | Formula / note |
|---|
Drive Diagram
Formulas & ISO 606 chain pitches
Geometry
i = z₂/z₁ = n₁/n₂d₁ = p / sin(π/z₁) [pitch dia]
d₂ = p / sin(π/z₂)
v = z₁·p·n₁ / 60 000 [m/s]
Chain length
X = a/p (a in links)L = 2X + (z₁+z₂)/2 + (z₂−z₁)²/(4π²X)
→ round to even integer
a_actual = p/4·[Y + √(Y² − 8·Δz²/π²)]
where Y = L − (z₁+z₂)/2, Δz = z₂−z₁
Wrap angle
α₁ = 180° − 60°·(z₂−z₁)/X_links(simplified)
or: α₁ = 180° − 2·arcsin((d₂−d₁)/(2a))
Minimum α₁ = 120°. Below this use a tensioner.
Polygonal effect
δv/v = 1 − cos(π/z₁)Speed variation due to chain link geometry. Higher tooth count → smoother running. z₁ ≥ 17 for smooth operation at higher speeds.
Standard ISO 606 pitches
| Pitch | Inch | ISO chain | v_max |
|---|---|---|---|
| 6.35 mm | 1/4" | 04B | 3 m/s |
| 9.525 mm | 3/8" | 06B | 8 m/s |
| 12.7 mm | 1/2" | 08B / ANSI 40 | 15 m/s |
| 15.875 mm | 5/8" | 10B / ANSI 50 | 15 m/s |
| 19.05 mm | 3/4" | 12B / ANSI 60 | 12 m/s |
| 25.4 mm | 1" | 16B / ANSI 80 | 10 m/s |
Design guidelines
- z₁ ≥ 17 for smooth running (z₁ = 19, 21, 23 typical)
- z₂ ≤ 120 to avoid long pitch engagement
- i ≤ 6 for single-stage chain drives
- Centre distance: 30–50× pitch preferred
- Even number of links avoids offset/half link
- Upper chain strand should be the tight side (slack side sags below)