The Märklin System

Courtesy Märklin

     It was Märklin that started Z-Scale and because Z-Scale was exclusively a German product for its first decade, there is a lot of German engineering in the scale. To be sure, things have changed in the intervening years, but at the core of things is a solid engineering design. This design predates Z-Scale, having been developed by Märklin in the early 1950’s for use with their H0 product line. Because the H0 line is AC powered and Z-Scale is DC powered, there are a few differences, but the basic design is pure Märklin. At the heart of this design is a color coded wire and plug system which allows the model railroader to connect electrical components together.  If you follow the color coding standards, you will likely get a reliable outcome. The wire colors are:

  • Red - Track power
  • Brown - Rail ground
  • Yellow - Accessory power
  • Gray - Accessory ground
  • Blue - Activating wires for accessories

NOTE:  As these pages were being written (October, 2005), Märklin was in the process of revamping its control boxes and the plug & sockets that are used with those boxes. As could be expected during such a transition, there is some confusion. The old control boxes and their related plugs & sockets date back to the early 1950’s, so there are a lot of them out in the market.  The new boxes are just starting to make their appearance, but they are improved and are the way of the future. From a wire’s perspective, it doesn’t matter what plug & socket is used, it is strictly a matter at the control box and at the distribution strip. And, it is possible to have an old style plug at one end of a wire and a new style plug at the other end. I note this because you may find some confusion with part numbers. A current catalog and a somewhat older catalog will be most helpful during this period of change.

     Basic electricity requires a complete circuit.  For locomotive power, electricity flows from the transformer through the red wire to the track, through the “red” rail to the locomotive, through the motor of the locomotive, back through the “brown” rail to the transformer. Any interruption to this circuit and the locomotive does not run. So it is with the accessory power, flowing through yellow to a light bulb and back via gray.

     In the case of solenoid operated devices such as track switches, uncouplers and relays, the power is controlled through a momentary control box such as the 72720. The yellow wire is connected to the solenoid device, then blue wires connect to the control box, which is connected via the gray wire back to the transformer.

     In this situation, electricity is not flowing until a button on the control box is pressed, which then allows current to flow.  The solenoid is a coil of wire in the operating device, and when electricity flows through it, a small slug of metal in the accessory is drawn into the coil, which operates the accessory.  Turnout points are thrown in this manner, the uncoupler is raised or the relay’s contact points are changed. It is not desirable to have continuous electricity flowing through the solenoid because heat builds up and eventually burns out the coil of wire. So, the 72720 is a momentary device; when you release the button on the control box, electricity stops flowing.

     The turnout and the relay both have two solenoids, with two blue wires connecting to the control box. To differentiate between these two wires, one is fitted with green plugs & sockets while the other is connected with red plugs & sockets.

Courtesy Märklin

     You will also discover an interesting but mysterious item, the 72090 Distribution Strip:

     The 72090, and its predecessor, the 7209, allow for multiple electrical connections of the same color. In the transformer connection illustration above, the distribution strip is used to connect multiple yellow wires, with a single connection being made to the transformer itself. The same could be done with gray, red or brown connections if the situation calls for it.  Obviously, blue connections must be made directly between the control box and the operating device. 

     In the case of two turnouts that operate in tandem (such as at a crossover), you can connect the two blue wires (one from each device) by using the holes in the side of the plug.  In this way, one wire can be run to the control box and when you operate the turnout, both will be properly set to each other.

     It should be noted that if you have two or more transformers on a layout, the yellow connections of each transformer should never be connected together.  One transformer can supply the “yellow” connection to street and accessory lights. A second can supply the yellow connection for the track switches and so on.  You must take care to not allow the different yellow circuits of each transformer to be joined together.

     As you get into the wiring technology, you will find that the Märklin system is very helpful, even for expert modelers.

 

Was the information on this page useful?

Page last updated 10/30/2005

[Guide to Z-Scale] [About These Pages] [History of Z-Scale] [Structures] [Planning] [Track] [Electrical] [Philosphy of Operation] [The Märklin System] [Solenoid Devices] [Signals] [Automatic Operation] [Accessories] [Catenary] [Building a Layout] [Scenery] [Maintenance] [Narrow Gauge] [Some Final Words] [Sources & Credits] [Links] [Legal Notice] [Useful?] [My Other Work]