KEVOS® MAKEOS · Mechanics
Geneva Drive Design (Acceleration, Pin Force and Drive Torque)
How hard does this Geneva wheel accelerate the load, what force does the drive roller see, and what torque must the driver supply?
Dynamic check of an external Geneva indexing drive: crank radius, index and dwell times and peak wheel speed (as the Geneva mechanism tool), the wheel’s angular velocity and acceleration through the indexing stroke found point by point, the torque to accelerate the wheel and load inertia plus friction, the force on the roller in the slot, and the driver torque by power balance, checked against your roller and drive ratings.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Number of slots | Number of slots in the Geneva wheel (indexes per turn). | |
| Centre distance | mm | Distance between the driver and wheel centres. |
| Driver speed | rpm | Speed of the driving crank (one index per turn). |
| Roller diameter | mm | Diameter of the drive roller. |
| Wheel and load inertia | kg·m² | Inertia of the wheel, table and load about the wheel axis. |
| Friction torque on the wheel | N·m | Friction torque resisting the wheel. |
| Allowable roller force | N | Allowable load on the roller and its pin (your value from the bearing or pin rating). |
| Driver torque rating | N·m | Torque rating of the gearbox or motor driving the crank. |
Method and formulas
- λ = sin(π ÷ n); crank radius a = λC; index angle of the driver 180° − 360° ÷ n (as the Geneva mechanism tool).
- With crank angle θ from the line of centres: ω_w ÷ ω = λ(cos θ − λ) ÷ (1 − 2λ cos θ + λ²); α_w ÷ ω² = λ(λ² − 1) sin θ ÷ (1 − 2λ cos θ + λ²)².
- Wheel torque = J |α_w| + T_f; roller force = wheel torque ÷ (C √(1 − 2λ cos θ + λ²)); driver torque = wheel torque × ω_w ÷ ω, each taken at its peak through the stroke.
- Example: a 4-slot wheel at 60 rpm peaks at 213.46 rad/s²; the roller sees 352.16 N and the driver needs 21.746 N·m.
Limitations
- Rigid parts and no clearance; impact at roller entry is not included.
- Friction treated as constant.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size the drive for a Geneva index table
- Check the roller and slot loads
- Compare slot numbers for smoother indexing
Who it is for
- Machine designers
- Automation engineers
- Design engineers
What you get
- Geometry, timing and peak wheel speed
- Peak angular acceleration and wheel torque
- Roller force and driver torque
Interpreting the result
- More slots lower the acceleration for the same index time but leave a shorter dwell.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 171. Topic reference; no source tables or recommended settings are reproduced.
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Open the Geneva Drive Design (Acceleration, Pin Force and Drive Torque) calculator
