Thanx Mr Rider.
LD,
I knew someone would call me on this.
It is a lot more complicated than this but basically when you magnetise ferrous metals you are aligning all the usually chaotic molecules in the same direction and creating a north and south pole but it is effectively (as an analogy) like an open circuit (electrical) with nothing attracting the north pole to the south pole and over time or with shock, vibration etc the molecular structure can settle back into a chaotic state and lose it's magnetic properties.
A keeper completes this circuit and keeps the magnetic field flowing and the molecular structure aligned.
If you have ever bought a horseshoe magnet you should have got a keeper with it in the form of a small metal bar across the two poles.
Still, I don't see how this knowledge can be applied to the magnets in a rotor.
LD,
I knew someone would call me on this.
It is a lot more complicated than this but basically when you magnetise ferrous metals you are aligning all the usually chaotic molecules in the same direction and creating a north and south pole but it is effectively (as an analogy) like an open circuit (electrical) with nothing attracting the north pole to the south pole and over time or with shock, vibration etc the molecular structure can settle back into a chaotic state and lose it's magnetic properties.
A keeper completes this circuit and keeps the magnetic field flowing and the molecular structure aligned.
If you have ever bought a horseshoe magnet you should have got a keeper with it in the form of a small metal bar across the two poles.
Still, I don't see how this knowledge can be applied to the magnets in a rotor.