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ELECTRO-MAGNETIC UNCOUPLERS |
To uncouple a pair of Kadees requires two magnetic poles of opposite polarity focussed just below rail level at either side of the track. I found that to effect reliable operation of Kadees with AG steel wheelsets required a number of modifications to the nomal magnet set up.
Firstly, permanent magnets proved to be of little use. In order to get a strong enough magnetic field, the magnets themselves needed to be quite large (as is Kadee's own offering) with the result that the steel wheels and axles are effectively attracted by this wide magnetic field. This also precludes the use of hinged permanent magnets as used so effectively on a number of standard HO layouts and elsewhere, where non-ferrous wheelsets are in use.
The solution was to be found in the use of electro-magnets (plus weighting of suitable freight cars with lead to around 250g) and after a number of attempts the design was finally refined to that shown (Picture 8).
N.B. Although I have decided to go down the electro-magnet route as I will be running a mixture of Alan Gibson and NWSL wheelsets, the arrival of the NWSL wheelsets in Nickel Silver and their sole use on a layout will mean a standard Kadee / permanent magnet set up could be used in theory.
Cross-
section showing parts required for 1 of a pair of electromagnets
The
plastic tube can be substituted by 11/32 ins round brass tube from the K &
S Metal Centre (stock no. 134)
PLEASE NOTE: Use about 800 turns not 300 as shown on the sketch.
The arrangement of the two magnets is shown below (Picture 9). I found there was a marginal improvement in the opening of the Kadees when the magnets were slightly offset (around 5 degrees) as shown. Also note the direction of the winding of the magnets which is necessary for opposite polarity to be achieved.
Electro-magnet set up and circuit
A look at the arrangement set up to test all of this P87 stuff. Off the picture at the left the track diverges into two short spurs by means of a #6 P87 turnout. The coloured patterns on the magnets are just fancy tape holding the wire turns in place (Picture 10).