KEVOS® MAKEOS · Power Transmission
Roller Chain Drive Design
Will this roller chain and sprocket pair carry the power, how long is the chain, and how smooth will it run?
Design check of a roller chain drive: sprocket pitch diameters, chain speed, design power with service factor against the per-strand rating and multi-strand factor, working pull and its safety factor on breaking load, chain length rounded to an even number of links, the exact centre distance for it, wrap on the small sprocket and chordal speed variation.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Power | kW | Power transmitted. |
| Small sprocket speed | rpm | Speed of the small sprocket. |
| Small sprocket teeth | Teeth on the small sprocket. | |
| Large sprocket teeth | Teeth on the large sprocket. | |
| Chain pitch | mm | Chain pitch. |
| Target centre distance (pitches) | Preferred centre distance in pitches (30–50 is common). | |
| Service factor | Service factor for the driver and load. | |
| Power rating of one strand at this speed | kW | Power rating of one strand at the small sprocket speed and tooth count (from the chain maker or standard). |
| Multi-strand factor (1 for single) | Factor for multiple strands (from the chain maker). | |
| Chain breaking load | kN | Minimum breaking load of the chain. |
| Chain mass per metre | kg/m | Mass per metre of the chain. |
Method and formulas
- PD = p ÷ sin(180° ÷ z); chain speed v = z₁ p n₁ ÷ 60,000.
- Design power = P × SF against rating × multi-strand factor; pull = P ÷ v + m v²; safety factor = breaking load ÷ pull.
- Links L = 2C + (z₁ + z₂) ÷ 2 + [(z₂ − z₁) ÷ 2π]² ÷ C, rounded up to even; exact C = p ÷ 4 {L − (z₁ + z₂) ÷ 2 + √[(L − (z₁ + z₂) ÷ 2)² − 8 ((z₂ − z₁) ÷ 2π)²]}.
- Chordal speed variation = 1 − cos(180° ÷ z₁).
- Example: 5.5 kW at 300 rpm on 19/57 teeth needs 120 links at 643.72 mm centres.
Limitations
- Ratings depend on lubrication; the per-strand rating must match your lubrication method.
- Two-sprocket drive without idlers.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Select a roller chain for a conveyor or machine drive
- Lay out sprockets and centre distance
- Check an existing chain against a power increase
Who it is for
- Design engineers
- Maintenance engineers
- Power transmission engineers
What you get
- Pitch diameters, speeds and chain pull
- Rating and breaking-load checks
- Chain length, centre distance, wrap and chordal action
Interpreting the result
- Small sprockets under 17 teeth run rough and wear fast; more teeth smooth the drive.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2537–2556. Topic reference; no source tables or recommended settings are reproduced.
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