Chain Drive Inputs
Example Data Table
Use these as sample inputs to test the calculator.
| Case | Power (kW) | Driver rpm | z1 | z2 | Pitch (mm) | Center (mm) | Ks | Strands | η |
|---|---|---|---|---|---|---|---|---|---|
| A | 5.0 | 1200 | 17 | 51 | 12.7 | 600 | 1.3 | 1 | 0.96 |
| B | 12.0 | 900 | 19 | 57 | 15.875 | 800 | 1.5 | 2 | 0.95 |
| C | 2.2 | 1500 | 15 | 30 | 9.525 | 450 | 1.2 | 1 | 0.97 |
Formulas Used
- Speed ratio: i = z2 / z1, and driven speed n2 = n1 / i.
- Pitch diameter: d ≈ p / sin(π / z), where p is chain pitch.
- Chain speed: v = π · d1 · (n1 / 60).
- Tangential force: Ft = P(W) / v, with P(W) = 1000 · P(kW).
- Design tension: Fd = Ft · Ks / strands.
- Torque: T(N·m) = 9550 · P(kW) / n(rpm).
- Chain length (pitches): Lp = 2m + (z1+z2)/2 + ( (z2−z1)² / (4π²m) ), with m = C/p.
- Wrap angle (small sprocket): α1 ≈ π − 2·asin((d2−d1)/(2C)).
How to Use This Calculator
- Enter power, driver rpm, and both sprocket tooth counts.
- Choose a chain pitch and a center distance estimate.
- Set service factor, strands, and an efficiency value.
- Provide allowable tension from your chain catalog.
- Press Calculate, then review speed, tension, and length outputs.
- Adjust pitch, teeth, or strands until safety factor is acceptable.
- Export CSV or PDF for documentation and approvals.
FAQs
1) What is a good minimum for driver teeth?
Many designs use 15–25 teeth to reduce chordal action and wear. Very small sprockets increase vibration, noise, and tension fluctuation.
2) Why is chain length rounded to an even pitch count?
Even pitch counts often match common connecting link arrangements. Rounding also helps align center distance adjustment to real, purchasable chain lengths.
3) What does service factor change?
It increases the calculated design tension to account for shock loads, starts and stops, misalignment, and duty cycle. Higher service factors mean more conservative sizing.
4) Does efficiency affect speed ratio?
No. Speed ratio is set by tooth counts. Efficiency reduces delivered power, which affects driven torque and can influence heating and overall drivetrain capacity.
5) How do multiple strands help?
Multiple strands share the transmitted load, reducing tension per strand. This can improve life and allow higher power, provided sprockets and alignment suit multi-strand operation.
6) What is an acceptable wrap angle on the small sprocket?
Higher wrap improves tooth engagement and reduces risk of skipping. Many designs target above about 120° on the small sprocket, depending on speed and duty.
7) Are these results enough for final chain selection?
They are a strong start, but final selection should also check lubrication, wear rating, speed limits, shock, environment, and manufacturer tables for allowable power and tension.