Magnetos In Ignition Engines

Magnetos that are used for ignition engines purposes are very complex, especially for those who are not working actively or frequently with them. To put it frankly and in simpler terms, an ignition magneto, or high voltage magneto, is a magneto that provides a spark-ignition motor, such as a petrol engine, with current for the ignition mechanism. It generates high voltage pulses for the spark plugs. The use of ignition magnetos is now primarily limited to motors where there is no other electrical supply available, such as lawnmowers and chainsaws. It is also commonly used in aviation piston motors, although there is an electrical supply

How a magneto works in conjunction with the engine is that the latter rotates a coil of wire between the poles of a magnet in a type known as a shuttle magneto. The magnet is rotated and the coil stays stationary in the inductor magneto. As the magnet moves towards the coil, the magnetic flux linkage of the coil changes. This, in turn, causes an EMF in the coil, allowing a current to flow in response. Just as the magnetic pole moves away from the coil and the magnetic flux starts to decrease, a cam opens the contact one or more times per revolution.

The loss or failure of magneto is uncomfortably prevalent. Mags are full of less-than-robust plastic components. That is, plastic is used because it is made from non-conductive material so it wouldn’t pose as much a hazard as working with conductive materials. Fortunately, most aircraft engines are fitted for redundancy with dual magnetos, and the likelihood of both magnetos failing at the same time is highly remote. Magnetos checks can detect gross ignition system failures during preflight run-up, but in-flight mag checks are much better at detecting subtle or incipient failures.

In most newer installations of magnetos, it typically only has one winding switch that is linked to an outer ignition coil. This outer ignition coil not only has a low tension winding, but it also has a secondary winding of several of levers that can convey high voltage necessary to engage spark plugs. This kind of process is known as an "energy transfer" because of the way that high voltage is relayed through the system. This process is seen as efficient because it was easier to instill a decent insulation for the second round ups of winding for an external coil. Nowadays, it's the insulation materials that have been improved to the point where constructing self-contained magnetos is relatively easy, but energy transfer systems are still used where the ultimate in reliability is required such as in aviation engines.

For more information on magneto and other ignition parts like gear magneto, body engine magneto, cap end magneto, shaft magneto, resonator magnetost, cover ignition, cable set ignition, look to the folks at ASAP Aerospace Hub. Owned and operated by ASAP Semiconductor, we can help you find all the unique parts for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at


December 15, 2022

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