Parallel-Axis Magnetic Gear Torque Calculator

Enter both wheels' outer diameter, pole count, magnet thickness, width and gap for a preliminary maximum transmitted (slip) torque, gear ratio and centre distance of a parallel-axis magnetic gear pair (such as the CJ series).

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Is yours a coaxial gear — nested rotors with a modulator ring between them?Use the flux-modulated coaxial gear calculator

1The two wheels

Wheels side by side (not to scale)

Driver wheel A — outer diametermm

Driver wheel A — polesTotal N + S poles around the wheel, even, 4–80. Both wheels need about the same OD per pole to mesh.

Driven wheel B — outer diametermm

Driven wheel B — polesTotal N + S poles around the wheel, even, 4–80. Both wheels need about the same OD per pole to mesh.

2Magnets and gap

Magnet thickness (radial)mmRadial depth of the magnet ring on its steel hub, same on both wheels; at most a quarter of the smaller diameter.

Magnet width (axial)mmWidth of the magnet rings along the shafts; both wheels overlap fully.

Air gap at the meshmmClosest distance between the two wheels' outer surfaces.

3Grade and temperature

Magnet grade (NdFeB or SmCo)

Working temperature°CBoth wheels at this temperature; if they differ, enter the hotter.

Calculating…

Preliminary estimate for a parallel-axis pair of radially magnetised wheels on steel hubs: magnetic-charge model (μr = 1 magnets; ideal steel hubs by alternating images in 2D, with an approximate end correction for the finite width), torque averaged along the meshing motion, static (no speed, eddy-current or windage effects), no fitted factor. Checked against AIC's 14 CJ-series catalogue models (identical pairs, 1 mm gap), modelled with N35 at mid Br, magnet thickness 0.15 × OD and width = column G: catalogue ÷ model runs from 0.61 to 1.80 (median 0.97), and 11 of the 14 fall inside the band shown (model × 0.75–1.35). Other grades, thicknesses and unequal pairs are extrapolation. Not for orthogonal, bevel or encapsulated drives. We confirm designs by measurement.

Send us your torque, speed and centre distance — we select or design the gears