Lego 7863 Forerunner Of Lgb Epl Drives?

[James Day]

I have always been drawn to the charm of LEGO trains, although I have not owned any myself for many years. I was lucky enough to attend the Toy Fair in London in 1980, which was the year Lego launched the conduit powered series of trains. They had an amazing display there.

They had point motors and signals in this series too. It lasted a decade or so. Here is the page I was viewing recently which shows the history of motors that Lego have used in their trains over the years: http://horst-lehner.mausnet.de/lego/ben/9v_12v.html

My specific query is about the Lego point motor 7863 If you scroll down you come to some text about it. Here is an image showing the insides of one: http://horst-lehner.mausnet.de/lego/ben/9v_12v/pi463.jpg

The text about the motor refers to it as a solenoid, but it does not look like one to me. Has anyone ever seen, used or handled one?

Here is my thinking:
Firstly it only has two wires, whereas all solenoids I know of need three wires: a centre common wire and two lives - One for each end to attract the shuttle.

I have long suspected that the LEGO point motor is more likely a permanent magnet rotating within a polarised coil - Like the LGB EPL system. The picture seems to show this, although not all the mechanism is exposed. (With this type of motor - When the coil is energised the selected polarity causes the magnet to deflect and provides the drive). Can anyone confirm or disprove this similarity?

As most of us will have found out, many solenoids do not take well to abuse or even plain over-use and either overheat giving that expensive smell we all know and love, or simply melt! A magnet rotating within the field of a coil would be a lot more robust and less prone to suffering from the China Syndrome, especially at the hands of children.

If I am right, it would be interesting to know if the coil is energised by full wave d/c (reversible) or a combination of a/c and half wave d/c - as used by LGB?

Research indicates that LEGO launched the 7863 unit around three years( ?) before LGB introduced their EPL drives. I wonder if LGB had been playing with or just watching developments at Lego too?

Just idle fascination you understand, but I would like to know.

Happy new year!

James

 

[Beddhist]

My guess is that there is a permanent magnet inside or next to the coil and the polarity is reversed to change direction.

 

[James Day]

Thanks Peter,


I tend to agree with you 100%


I have looked around for instruction sheets for these units on the net and they all suggest reversing the leads if the unit works the opposite way round to what is intended. This supports both our assumptions.


Also the switches that control these units appears to be fed with a 12v DC take off from the transformer.


Further research shows that there was an earlier Lego Point motor, for the older 'blue rail conduit' supplied trains, but that these definitely were solenoids and had a three wire feed.


So from my research so far it looks like Lego got there first with this type of motor, but LGB took it a stage further by making the supply half wave and consequently much easier to automate.


James