KEVOS® MAKEOS · Gears
Internal Gear Drive Check (Proportions, Tooth Difference, Pinion Bending)
Will this pinion and internal gear mesh without interference, what are their proportions and centre distance, and is the pinion strong enough for the power?
Check of a spur pinion driving an internal (ring) gear: pitch diameters, centre distance, enlarged and conventional internal and outside diameters and the tooth-number difference against the minimum for the tooth form (as the internal gear proportions tool), the ratio and output speed, pinion torque and tangential force from the power, and the Lewis bending stress with the velocity factor (as the Lewis bending stress tool) against your allowable.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Module | mm | Module of both gears. |
| Internal gear teeth | Teeth on the internal gear. | |
| Pinion teeth | Teeth on the pinion. | |
| Tooth form | choice | Tooth form of the pair. |
| Load | ||
| Power | kW | Power transmitted. |
| Pinion speed | rpm | Speed of the pinion. |
| Face width | mm | Face width in mesh. |
| Lewis form factor of the pinion | Lewis form factor for the pinion tooth count and form (from your gear data). | |
| Tooth manufacture | choice | How the teeth are made (sets the velocity factor). |
| Allowable bending stress | MPa | Allowable bending stress of the pinion material. |
Method and formulas
- Pitch diameters m Z; centre distance = m (Z_g − Z_p) ÷ 2; enlarged and conventional diameters and the tooth-difference rule (as the internal gear proportions tool).
- Torque = 9549 P ÷ n; tangential force = 2T ÷ pinion pitch diameter; output speed = n Z_p ÷ Z_g.
- σ = K_v F_t ÷ (b m Y) with the velocity factor for the manufacture (as the Lewis bending stress tool).
- Example: centre distance 81 mm; ring turns at 362.5 rpm; pinion bending 41.145 MPa.
Limitations
- Lewis bending only; surface durability (pitting) needs a separate check.
- Proportions follow the handbook rules for internal gearing; tip relief may still be needed.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check an internal gear drive for a turntable or slewing ring
- Size the pinion of a ring gear drive
- Avoid interference in internal gearing
Who it is for
- Gear designers
- Machine designers
- Design engineers
What you get
- Diameters, centre distance and tooth difference
- Ratio, torque and tangential force
- Pinion bending stress
Interpreting the result
- Internal gears share load over more teeth than external pairs, so the Lewis check is conservative.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2170–2171, 2131–2160. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Internal Gear Drive Check (Proportions, Tooth Difference, Pinion Bending) calculator
