# Magnetic drive system

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Transmission ratio, overload behaviour, preliminary calculations and the required slip-torque validation.

In brief

Transmission ratio, overload behaviour, preliminary calculations and the required slip-torque validation.

**Magnetic coupling interface.** CAD record; transmitted torque remains subject to bench measurement. [I02]

**Driving pinion construction.** Original component view from the v2.0 report. [I02]

**Driven-ring magnet layout.** Geometry supports the analytical transmission model; slip torque and endurance require measurement. [I02]

## Design definition

 |
 Parameter | Design record

 | Driving wheel teeth | 15
 | Driven wheel teeth | 146
 | Nominal ratio | 146/15 = 9.733:1
 | Magnet type | NdFeB N42, Ø8 × 3 mm in the v2 specification
 | Nominal air gap | 2.5 mm in the v2 specification
 | Intended behaviour | non-contact torque transfer with overload slip

## Kinematic model

 MAG-1 i = Z 2 Z 1 = 146 15 = 9.733 i=\frac{Z_2}{Z_1}=\frac{146}{15}=9.733 i = Z 1 ​ Z 2 ​ ​ = 15 146 ​ = 9.733 Nominal transmission ratio.

**Explanation**The ratio between driven and driving teeth defines how much the drive reduces speed and increases available torque.

 MAG-2 n 2 = n 1 i n_2=\frac{n_1}{i} n 2 ​ = i n 1 ​ ​ Nominal driven speed if synchronism is maintained.

**Explanation**Driven speed is motor speed divided by the transmission ratio.

 MAG-3 T 2 = 60 n 2 T_2=\frac{60}{n_2} T 2 ​ = n 2 ​ 60 ​ Driven-wheel rotation period in seconds.

**Explanation**Dividing 60 by the driven speed gives the duration of one output rotation.

## Why the earlier force estimate is not a final result

A magnetic dipole approximation can support preliminary sizing, but the short separation, finite cylindrical magnets, alternating polarities, tooth geometry and simultaneous interactions violate the simplest far-field assumptions. The resulting torque must therefore be treated as an analytical estimate, not a verified 3.9 N·m capability.

## Required validation

 |
 Test | Method | Reported output

 | Static slip torque | force gauge at known radius | torque-angle curve and peak slip torque
 | Starting load | incremental drum load | minimum starting torque and motor current
 | Speed stability | encoder or video tachometry | mean RPM, SD and periodic ripple
 | Endurance | loaded operation over defined hours | slip events, temperature and drift
 | Misalignment | controlled axial/radial offset | torque margin and failure threshold

 MAG-4 S F = τ s l i p , m e a s u r e d τ r e q u i r e d , m a x \mathrm{SF}=\frac{\tau_{\mathrm{slip,measured}}}{\tau_{\mathrm{required,max}}} SF = τ required , max ​ τ slip , measured ​ ​ Safety factor based on measured slip torque and measured worst-case required torque.

**Explanation**Measured slip torque is compared with the largest required torque. A value above one leaves a positive operating margin.

## FlavoRotor design provenance

The system-specific configuration on this page is traced to the supplied FlavoRotor engineering records. [I02]

## References

- [I02] FlavoRotor project team (2026). FlavoRotor v2.0 system architecture. *Internal engineering design report*.