Z Scale Modules

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ZoCal notes:

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  • 11 Henri S
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Why modules?

The concept of modules, not only for clubs and displays, but as a layout you can set up at home is great.

  • portability
  • share with others
  • change track plans
  • can be stored away in a small space

Please note that I have taken a lot of following from emails, so if you see some familiar sentences, I apologize for the plagiarism! It's for the common good!

Module standards/specifications:

Most people use the Z-Bend Track standard (ZBT) as a basis for their modules. Apparently the original site is gone, but the PDF of th estandard is hosted here:  http://www.ztrack.com/resources/Z-Bend_Track_Manual_2004.pdf 

The idea is that modules have at least 2 tracks on the outer edge of a 24" wide module. The tracks are located at a standard offset from the center of the module, 9" and 10", so making a wider module will still allow them to mate. The length can be anything. You can also have curved modules, or 45 degree or 90 degree.

This standard has not been improved or updated since 2004. There's improvements that many people make that don't violate the standard, but it really should be updated.

Basic dimensions:

The Z-Bend manual tends to "think straight", but as long as the specification that the tracks are 9" & 10" from the module center line (at the ends of the module) is met, the tracks can curve in between. Also the standard tends to focus on straight, rectangular modules, more variation is OK.

"Module" height is actually supposed to be written as "top of track" height. The height should be 50 inches. This is higher than most other scales, but it works well because Z is smaller. The height is also convenient for working on the modules.

The modules without legs are typically 5" high.

Physically connecting modules:

The modules have track that should stop 2-1/8" from the end of the module. Marklin expandable track sections are used to connect the track between modules. The standards call for where the joiners are and were written before MTL track. In the construction pages I will address this.

Electrically connecting modules:

The standard calls for four DB25 connector, one at each "mainline" connection, remember you have two double track mainlines per module. These connectors are used on old serial ports on computers, two rows of pins, 25 total.

While not designed for high current, groups of 3 pins are used together to increase current handling capability. The connector basically carries the inner and outer mainline power. There are other pins and uses, but this is the basic way power is transmitted.

"Deviation" from the ZBT standard

Please note that the Z-bend standards were written before MT (Micro Trains) and Rokohan track was available.

Also note that no one has revised them to benefit from experience gained since they were written.

My opinions are based on what I have seen work and learning from people who run modules very successfully.

Joiners for the expansion tracks at the ends of the module:

I suggest using the MT joiners (part number 958 [990 40 000] ). They fit the wider rail base of MTL flex and clamp tightly on all three manufacturer's rail web.  Some like the Peco type but some people find them extremely loose and only hold on the rail base.  Märklin joiners (8954 or 6705) should be avoided at all costs.  They are very thin metal, bend easily and will quickly wear out which means loose, damaged, etc.  In addition, they will NOT fit on Micro-Trains flex track as the MTL rail base as about .008" wider than Märklin's.  The MTL track will spread the Märklin joiners open too far.

ZBT standards call for rail joiners on the module tracks, none on the expansion tracks. My experience has shown that the joiners get damaged, and unless you solder them on (read next paragraph), you cannot guarantee where they stay. I just let them stay where they want, and keep spare joiners on hand. Replace them when they get damaged.

From experience, I recommend that the joiners are NOT soldered on. By all means, do NOT use CA glue either! First, very few people can solder joiners without melting the track. When (not if, WHEN) joiners get damaged, it's much harder to remove one that is soldered on. Even if you get it off without damage, you still have to contend with solder left over on the rail, and the new joiner will not sit in place properly. It's just a mess. Get a box of joiners.

In some cases, you actually want to not have metal joiners on the connector tracks, and might use insulated joiners. This helps debugging electrical problems and also facilitates using independent power blocks using their own circuit protection. More on this in other sections.

If you really want to affix the joiners, it's much safer and easier to do it to the expansion track. You can pull the rails completely out of the expansion track to solder with no danger of melting anything. Also, you can glue the insulated joiners on them with no ill effects. (read more elsewhere about not using the expansion tracks to conduct power and also modifying expansion tracks for better performance)

Roadbed preparation:

The basic goal is, where the expansion track is, the roadbed or ballast must clear the expansion track; give yourself  at least 1mm of clearance. This minimizes bowing or humps/dips between modules. Even though it might not look as nice, if the expansion tracks are bowing up, you can tap them several times to get them level. With no space underneath, you cannot "tweak" the expansion tracks.

(read elsewhere on my methods of preparing the expansion tracks.)


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