Self Tending Marx Switches

[balidas]

Some time back somebody asked about wiring Marx turnouts. I can't find the thread so I'll post this here. I just ran across this in the file section of the Marx Traders Yahoo Group, authored by  member  Gigeastman.

Self Tending Marx Switches

Marx switches are not designed to be self tending, or automatic. The operator must throw the switch ahead of his train as it approaches each switch. This can require a lot of concentration to avoid derailments, and makes it impossible for the operator to step away from the controls even for a second.

Marx switches can be made self tending by wiring them with control sections in the rails of approach tracks. The secret is that Marx switches are wired the opposite of Lionel - the control section for Marx has to be in the center rail, not the outside rails. The switches will be activated when the center pickup shoe of the engine touches the control rail. This means, of course, that a train operating in reverse, led by a car with no center shoe, or led by a mechanical engine with no center pickup, will not operate the switch automatically.

To make the control sections in the approach rails:

1. Set up a switch and its Marx control panel.
2. Cut a piece about 1" long from an approach track center rail to become your control section.
3. Solder a track feeder to the middle rail on either side of the gap to provide continuity.
4. Solder a wire to the 1" piece long enough to reach the switch terminals.
5. Place insulating rail joiners in both ends of the control section. (Wooden toothpicks work.)
6. Insert the control section back into the track section.
7. Connect the wire from your control section to either the red or green terminal on the switch.

As your train approaches the switch, its center pickup shoe will bridge the gap you have just made in the control section. Current will flow from the back of the shoe contacting the continuous track, through the front of the shoe contacting the control section, then to the switch itself, activating it to swing in favor of the approaching train. It may require a couple of attempts to get the control section lined up level and smooth for the engine's pickup shoe to operate properly.

[ADCX Rob]

That's an awful round-about way..

You can use a method with insulated outside rails or 154c contractors as recommended by Lionel for their 1121 switches:

Power the center, common posts of the Marx switches with track(center rail) or accessory(fixed voltage) power(which is different from Lionel - their center post is common ground connected through the frame of the switch) instead of common as recommended by Marx. 

Do not connect track or accessory power to the Marx controller, but connect common ground to the bus or clips that connect(momentarily) to the red and green pushbuttons.  There will only be two wires from the controller to each switch instead of three.

This is one of the advantages of Marx switches - you have the option of using a fixed accessory voltage, with a non-derailing feature, without making modifications to the switch as required with Lionel 1121, 1122/1122E, 5122/5123 type O-27 switches.

[lionelsoni]

Keep in mind that adding this feature to the Marx turnouts leaves them vulnerable to burnout in the same way as the later Lionel turnouts, and more so if they are powered by a fixed voltage rather than track voltage.  I recommend combining this modification with a capacitive discharge circuit, to avoid the risk entirely.

[ADCX Rob]

I absolutely agree with this - even more imporatant with the Marx low profile palstic switches.