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Magnetic Gears

From DT Online

Magnetic cogwheel1.gif


Description

Magnetic Gears (or Magnetic Couplings) transfer motion by means of repelling magnets rather than interlocking mechancal gear teeth.


Features and Applications

A form of Magnetic Gear can be created simply by replacing gear teeth with permanent magnets with alternating magnetic fields as shown in the model. Since there is no physical contact, they are not subject to wear. They cannot transmit as much Torque as conventional gears but have the advantage of slipping if overloaded.

Magnetic gear 26 o.gif


Commercial Magnetic Gears arrange the gears as a series of concentric rings comprising inner and outer rings of permanent Magnets separated by a Modulator Ring of Ferromagnetic Steel pieces embedded in a non-magnetic tray.


Due to the small air gap between all rings, there is no friction to account for. The actual implementation of such a gear may vary, and the Modulator Ring may either act as a Stator or can be directly attached to the output shaft, with the outer magnet ring then acting as a Stator.


Coaxial magnetic gears can be extraordinarily efficient, almost maintenance free. At low speeds, they achieve efficiencies in the range of 99.9 %. The high gear ratio of Magnetic Gears makes them interesting for stepping up very slow input forces, such as ocean Wave Power and Wind Turbines or stepping down high engine speeds for Marine Propulsion for example.


Animations
Magnetic Gear
Magnetic Gear Development for Renewable Ocean Energy - the University of North Carolina Coastal Studies Institute is working with researchers at UNC Charlotte to develop magnetic gearing systems for use in renewable ocean energy applications.


DT Online Buyers' Guide
  • Gears, whether of the same size or different diameters, will only Mesh together if the size of the teeth are the same.
  • The size of Gear Teeth is measured along the circumference of an imaginery Pitch Circle but is more easily calculated by dividing the diameter of the Pitch Circle by the number of gear teeth.
  • The Gear Teeth size is known as the Modulus or Module (m) and it must be the same for any meshing gears.
  • Always check this before purchase - contact supplier if not stated.

Click top left to enlarge

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