KEVOS® MAKEOS · Gears
Cam Pressure Angle
What is the maximum pressure angle for this cam rise, base circle and roller follower?
Maximum pressure angle and its position for a radial (in-line) roller follower on a disc cam, from the base circle, roller radius, rise, cam angle and motion law, against a limit.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Motion law | choice | Motion law of the rise. |
| Rise | mm | Total follower rise. |
| Cam angle for the rise | ° | Cam rotation over which the rise occurs. |
| Base circle radius | mm | Radius of the base circle (smallest cam radius). |
| Roller radius | mm | Radius of the follower roller. |
| Maximum pressure angle allowed | ° | Largest pressure angle your design allows (about 30° for translating followers is a common guide). |
Method and formulas
- Prime circle radius Rp = Rb + Rr.
- Follower displacement y(θ) and slope dy/dθ from the motion law.
- Pressure angle φ = atan((dy/dθ) ÷ (Rp + y)); the maximum is found by sampling the rise.
- Example: a 20 mm cycloidal rise over 90° on a 40 mm base circle peaks at 23.233°.
Limitations
- Radial (in-line) translating roller follower; offset and oscillating followers need different relations.
- Undercutting (radius of curvature) is a separate check.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose the smallest base circle that keeps the pressure angle acceptable
- Check a cam design for jamming
- Compare motion laws
Who it is for
- Machine designers
- Automation engineers
What you get
- Maximum pressure angle and where it occurs
- Prime circle radius
Interpreting the result
- If the pressure angle is too high, enlarge the base circle or spread the rise over a larger cam angle.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2284–2309. Topic reference; no source tables or recommended settings are reproduced.
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