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How does a Linear Motor work? Answered

Spell it out for me, i'm having a hard time understanding it.


There are permanent magnet linear motors, and there are inductive linear motors. The inventor of this type of levitating linear motor was the maverick electrical engineer Eric Laithwaite in England in the 1960's.


Laithwaite was one of THE best lecturers I ever heard. His "Christmas lectures" were both brilliant, and the book of the lectures shows how he did his linear motors.

He was one of my all-time greats.  He did a lot of work at Manchester University, and a lot of the senior engineers in the area that I knew, also knew Laithwaite. I met him on several occasions, and he always had time to talk engineering. His understanding of magnetic fields, and their interactions was astonishing. He had his obsessions, and they cost him his reputation later on.

Yes, that's always sad when a great person gets pidgeon holed for an aberration...

I'm sure glad for his work on maglev...

And I remember this development clearly from the time.

"In the 1980s, he was involved in creating a device to extract energy from sea waves (see patent
GB2062114); although the technology was successful in trials, it could not be made storm proof, hence it never became a commercial success." 

Look up "How does maglev work?" on google. A maglev train is a great example of a linear motor.

Linear motors work like standard motors, except they're laid out flat instead of in a circle.  Are you familiar with the concept?  There is a line of electromagnets and a permanent magnet.  Each electromagnet (EM) turns on in series, which pulls the permanent magnet (PM). 

So basically, the first EM turns on, and pulls the PM towards it, then it turns off, and the next EM in line turns on, pulling the PM towards that, and so on and so forth. 

I hope that helps!  I looked at this and thought it would be easy to answer, but as I tried to write it down I found that it's a lot more complicated to explain than I thought.

Example involving the mode depotdevoid suggests:

The dragster rollercoaster, it accelerates passengers horizontally by pulling the magnets in the car sequentially one at a time to each successive electromagnet along the track; extremely powerful, and has no moving parts except the coaster-car.  Other types like this involve friction between wheels and the bottom of the car to drive it forward.  The linear electromagnetic motor is much simpler to maintain in this case.

A variant of a linear motor would have only one magnet and only one electromagnet - the variable electric field (thus variable magnetic field) means the moving parts move a variable amount.  Key example:  The armature in a hard disk drive.  It only moves back and forth, not around and around like a normal motor would.