Naked Science Forum

Non Life Sciences => Technology => Topic started by: Don_1 on 29/08/2008 13:10:40

Title: How does a linear motor work?
Post by: Don_1 on 29/08/2008 13:10:40

Does anyone recall a trial of a linear induction train in the late 60's early 70's? It had no motor, but was pushed along at speeds of up to 360 mph by the traverse of electricity along a single rail. The electrostatic field between the rail and the train made the train 'hover' above the rail. If you do, have you any idea what became of it? I seem to recall it being shown on an edition of 'Tomorrows World' many many moons ago.

Title: Re: How does a linear motor work?
Post by: peppercorn on 29/08/2008 13:58:09

Is this not the same as MAGLEV trains like the 'bullet' train in Japan?

Title: Re: How does a linear motor work?
Post by: Don_1 on 29/08/2008 15:32:57

Yes, this is the the chappie, but what ever happened to it here in the UK where I think it was invented? Why did we never develop the concept. Or did we? It couldn't have been the 'wet leaves on the line' excuse, could it?

Title: Re: How does a linear motor work?
Post by: RD on 29/08/2008 17:34:48

"Bullet" speed trains couldn't run on the UK's existing rail network: they don't do bends.
Tilting trains  (http://en.wikipedia.org/wiki/Tilting_train#Advanced_Passenger_Train) are a solution of increasing train speed on bendy track.

Title: Re: How does a linear motor work?
Post by: LeeE on 30/08/2008 13:58:14

The 'Bullet train' is a direct english translation of the early project name for the Shinkansen, which run on conventional standard-gauge railways, although as RD points out, they don't do tight radius curves.  The Shinkansen has now been extended to include MagLev trains.

http://en.wikipedia.org/wiki/Shinkansen (http://en.wikipedia.org/wiki/Shinkansen)
http://en.wikipedia.org/wiki/Maglev_train (http://en.wikipedia.org/wiki/Maglev_train)

Title: Re: How does a linear motor work?
Post by: teragram on 31/08/2008 12:11:29

The phrase "Linear Induction" may be the key to this question. Eric Laithewaite,(a genius, sadly of little public regard in the U.K.) at I think Manchester (U.K) University realised that if the field arrangement in an ordinary 3phase motor was "unrolled" it could operate as a linear motor. The rotating part of the motor would be replaced by a straight aluminium bar, along the centre of a pair of rails. This arrangement was proved to work. An extension of the idea was that the vehicle containing the linear motor could be made to hover because of the effect of the magnetic fields. As usual, U.K. attempts to translate the ideas into reality were less than half-hearted. The passenger link at Birmingham International Airport was originally a "MagLev" sustem, but was never successful, eventually being replaced by I think a conventional monorail. The idea has now been adopted   by the Japanese and Germans.  

Title: Re: How does a linear motor work?
Post by: Pumblechook on 31/08/2008 12:59:21

Eric and gyroscopes makes interesting reading.

Title: Re: How does a linear motor work?
Post by: teragram on 01/09/2008 13:11:49

And how, Pumblechook!!

Title: Re: How does a linear motor work?
Post by: lyner on 02/09/2008 09:25:59

It was a shame. If another, 'legit' Scientist had been prepared to talk to him about the question, he would have seen where his Maths was dodgy and been able to move on without being drummed out of the system. He constantly claimed that he needed help with the Maths which was "too hard" for him.