The 5 Minute Marx Switch Fix

As I have mentioned in previous posts, I use Marx turnouts (switches) throughout my O27 layout. I like these because they are compatible with virtually any locomotive and rolling stock ever made that is designed for O27 curves. I find that all makes of trains travel through these turnouts smoother than on modern designs, especially at high speeds or when backing up. These turnouts are also easy to find, durable and inexpensive. All that is required for nearly all locomotives and cars is a simple 5-minute alteration to the original Marx design.

What Is The Difference?

A typical Lionel O27 turnout. Note the guardrails.

The main design difference between old Marx turnouts made between circa 1940 and circa 1970 and those of other companies is their "frogless" design which eliminates the need for guardrails on the turnout. Modern turnouts operate much like the prototype (real railroad) designs with movable "points" at one end which lead the wheels of the train to one of two routes. The spot where the diverging route meets the inside straight rail a v-shaped rail, called a "frog" is created. Also, a gap must be present in the inside straight rail and the inside diverging rail to allow the flanges of train wheels to pass. To prevent the train from derailing on this gap guardrails are required on the opposite side which keep the wheels from falling into the gap.

A typical Marx metal turnout. Note the movable rails.

On older Marx turnouts, both the diverging rail and the center rail swivel as a single unit from route to route. Thus there are no frogs and no gaps, and therefore no guardrails are required. This creates a smoother passage for the train as there are no gaps to "bump" through and no chance of wheels derailing on such gaps. So, while more modern turnout designs for O27 trains look more realistic, the old metal Marx design offers several operational advantages.

"Fat" Wheels

So why did Marx design their turnouts differently than other manufacturers? The main issue is the so-called "fat wheel". On many early O gauge and O27 locomotives the spur gear from the locomotive motor turned the drive wheels directly via large gears attached to the back of the drive wheels themselves. The diameter of these gears was often the same or only slightly smaller than the drive wheels themselves. This created a "fat wheel" that could not pass through guardrails or other track obstructions. While most manufacturers abandoned the "fat wheel" prior to 1942, Marx maintained the design on all locomotives until 1950, and continued it on many Marx locomotives until the end of Marx production in the 1970's. Therefore, Marx kept the frogless design to accommodate their contemporary line of locomotives.

Fat Wheels on a Marx #400 Steamer

Pick 'Em Up Right

The other difference between Marx products and other, and the one that requires our "fix", is in the design of the electrical pickups on the center rail.  Marx locomotives, as seen in the top photo on the left, use a long copper strip that slides along the center rail. This design maximizes the contact area with the center rail and also prevents the pickup from catching on any gaps that may exist in the center rail due to crossings, turnouts or other special track sections. These pickups, which are also used on Marx's "small gear" locomotives, have no trouble passing through turnouts made by any manufacturer.

Smaller Gears on a Lionel #8141 Steamer

The Catch

Lionel and most non-Marx locomotives use small roller wheels to contact the center rail. These wheels reduce friction with the track but have a smaller contact area and are susceptible to snagging on small gaps in the center rail. Lionel turnouts are designed so that these gaps are small enough to prevent snagging by these pickups. Marx turnouts, however, are not designed this way and some roller pickup locomotives, but not all, may catch on these gaps in the Marx turnout and derail. This is why many O27 operators believe that Marx turnouts are not compatible with Lionel and other locomotives. We will see, however, that this problem can be easily corrected.

Getting Pinned

Center rail gap on unmodified
Marx turnout when set for straight
route.

Center rail gap on unmodified
Marx turnout when set for
diverging route.

The photos above show the locations of the two center rail gaps on an unmodified Marx turnout. These gaps are sufficiently large that roller pickups on some locomotives and cars can drop into the gap, snap the rail, and cause a derailment. The fix for this is to bridge these gaps with simple rail joiners - any O27 brand joiner will work. Simply insert a track pin into the fixed center rail so that it rests as close as possible - but not touching - the swivel rail on either side. This provides not only a physical bridge but an electrical one as well, improving the performance of roller pickup equipment through the turnout.

Friction does well to keep the pin in place, but a drop of ACC cement or a quick touch with a soldering gun will make the fix more permanent.

Marx turnout modified with track pins.

Marx turnout modified with track pins.

And thus, your Marx turnouts may now accommodate not only your Marx locomotives and rolling stock, but that of Lionel and other manufacturers as well! Please note that this trick works only with the metal Marx turnouts. The plastic Marx O27 and O34 turnouts are different in design and are not recommended for use with the locomotives of other makers.

**Note: I have an eclectic collection of postwar and modern locomotives by a variety of manufacturers. To date, I have found only one locomotive for which this fix does not consistently work. That locomotive is a "Beep" diesel by RMT. However, I have found another simple solution that works for that locomotive - and any other that shares its difficulty with Marx turnouts. I will share that solution in a later post. Until then, Happy Railroading!