Section Five: Special Modules

If you want to make a square or rectangle (the normal loop type of operation), you need corners -- four of them. And with limitations of size of rooms as well as transportation methods, you can't always have those desirable O-72 corners, so we first present a compact corner made with O-gauge O-42 track. If your space is even more critical, you can make a corner similar to this with regular O-31 track and still get good results, but you will be restricted to using the smaller equipment. We'll leave the actual design up to you.

This module is based on a 33" square with the fascia outside of this dimension. The original used 1/4" plywood for the fascia and the deck, making for a very light, yet sturdy, construction. You might want to vary your size slightly to fit your own purposes.

Both tracks on this module are O-42 (21" radius), one of which ends at the edges of the module and the other requiring some straight track, either going to the edge of the module, or all the way to the connection 5" inside your neighbor's module (which means fewer track sections and better electrical transmission).

If you're using this corner with 24" wide modules, cut off the dotted rule and you'll have a module 30"x47" on the diagonal -- the longest dimension. If using 30" wide modules, just nip off the upper right-hand corner and your dimensions will be 35"x47".

An O-72 Corner

If you like wider curves and have the space to carry and use them, you'll want to try some O-72 corners. Construction can follow those detailed in Section 1: Construction of this manual, or can be of your own design. We suggest that you keep it simple, and by all means, keep it light.

The illustration at the right should give you all the information you need for these corners. The inside track ends at the edges of the module, so remember to supply two connecting 5" tracks to bridge to the next module. The outside track ends 5" from the edges of the module, so your standard 10" track pieces will bridge the gap.

Howard Packer doesn't like regular Lionel O-31 curves because they're too sharp for good operating and appearance. The wider the better for him. He does, however, understand the need for portability as much as the next fellow, so he devised the corner module diagramed and discussed in this section. He has used an O-72 curve for the front (outside) mainline and combined O-42 and O-72 curves for a second mainline in a module only 39" square.

Now before you say that this doesn't fit our 48" measurement (or multiples thereof), we'll agree, but a corner module doesn't necessarily have to be confined to the 48" measurement. Whwere you will have trouble is when several people bring corner modules and they're not all the same dimensions. You need matched pairs diagonally from each other. For example, if you used two of Howard's and two of the smaller corners diagonally across from each other, you still achieve a working rectangle.

Another place where this odd dimension will cause trouble is in making an S-shape within a basic rectangle, or if you have two T-modules and want to connect the two sides of a rectangle through the middle with a series of modules. If you're using two return loops for an irregular point-to-point layout, no problem.

Varying Construction

We think the accompanying illustration is self-explanatory, but will add that Howard has used the alternate construction method with side members of 1"x4" material around the perimeter of the module; and in his case he ripped his own boards so the actual dimensions are 3/4"x4"; but we prefer the narrower 3 1/2" ( or 3"), which is just as strong, but a tad lighter. He used 1/2" plywood for the deck so he needed no additional joists. This is very strong, but it's also a little heavy. We've found that experience has taught us a very strong lesson that lighter is better!

Howard can give you his philosophy and construction methods in his own words.

Packer's Compact Corner

By Howard Packer

The reason I designed this particular corner module was to allow for the wide radius curces on the smallest possible table surface. Also, that the module would mate neatly with adjacent two-foot wide modules, and still have at least 3" (the standard is 3 1/2" -- plan accordingly) from the edge of the plywood to the first center rail.

I took a little license with track radius because Lionel uses the outside rail to determine diameter. I used the centr rail because it's always in the center and is a very logical way of determining the diameter of such a circle. (Editor's note: most track plans are geared around the track centerline in determining a curve's radius.)

Because of the variable tolerance in quality controls where the track is made, some of the measurements have to be fudged and some of the track bent ever so slightly.

From one 4'x8' sheet of plywood I was able to make two corner modules and had enough material left over for a T-module top.

My Procedure

  1. To start, pick out the best corner on a 4'x8' sheet of plywood. Mark that as "A."
  2. Measure 39" along each edge from "A." Mark these locations as "B."
  3. Use a large carpenter's square to draw lines from the two points marked "B" to a point you will now mark "A1." This gives you a 39" square.
  4. Draw a diagonal line from "A" to "A1." This marks the halfway point of your curves.
  5. From both points "B" measure in the direction of "A," 3" from the edge of the plywood (if your fascia is outside your plywood this is fine). Then measure an additional "8 1/2". These are the positions where the center rails should lie at the edges.
  6. From "A" measure 39" in the direction of "A1." This marks the edge of the board at the middle of the turns. Three inches back is "C." Make a mark where the center rail of the outside curve should be.
  7. Use a square and extend a line about 4" from where the center rail of the inside curve is to come to the edge of the plywood. This helps to locate the curved track.
  8. Assemble your track and use the center diagonal line and end markers to make the curves fit.
  9. Note how the inside curve comes up to the two lines you drew from the edge. The O-42 track sections are 30 degrees each, so two make 60 degrees. You need two 15" sections of O-72 track (each section of which equals 22 1/2 degrees) to make a 90 degree square approach to the edge. This means cutting the O-72 track into two short pieces. Finish with two short straights about 3" long. Before cutting any track, put the full pirces in place and then measure carefully. The plan (Figure 5-6) shows how I cut my modules. You can use the first top you cut as a template for the second, and so on. (Editor's note: With K-Line and Lionel's introduction of O-54 O-profiled track, Howard has since replaced the inside track with O-54 and a 1" fitter track in the middle. It supports some of the larger equipment that O-42 can't.)
Measuring and Cutting Tie Into Adjacent Modules Legs for the Module
Gargraves Wide-Radius Variation

by Matt Jackson

Some of the modern Hi-Rail equipment barely makes it around even the O-72 curves. And those 72' and 80' passenger cars have quite a bit of overhang. Fortunately, with more manufacturers entering the three-rail sectional track market, a wider-radius corner using sectional track has become viable. The track used in this module is the new GarGraves sectional track -- specifically O-72 for the inside mainline and O-88 (with a small fitter section in the middle) for the outside. If you are familiar with the construction techniques involved with Howard Packer's corners and the full O-72 corner mentioned above, this wide-radius version should be easy.

Basically, you start with a the same platform as the full O-72 corner which is a 4'x4' half-sheet of plywood with two diagonal cuts, each 24" off opposite corners. Next, you lay the O-72 Gargraves on the inside main which will be 12" in from the edge; the O-89 curves will be exactly 8 1/2" from the inside mainline and will be 3 1/2" from the module edge -- perfect. Leg and fascia construction are identical to those in Howard's corners, but will obviously be enlarged to handle the larger module deck size. Construction costs will be similar to the compact corner, but the track cost will be higher -- approximately $160 for two loops of track ($40 per module).

You should also be aware of a couple of other items.

First, the module will occupy more space and might not fit in some small vehicles. Of course, with the added size (48" square as opposed to a 39" square), comes additional weight.

Second, some considerations have to be taken for adapting to conventional Lionel/K-Line O-Gauge track (GarGraves on standard cork roadbed is approximately the same height as Lionel O-Gauge). Using GarGraves bridge tracks with adapter track pins would probably make the transition into the corner module smoother.

If you like a wider curve for larger equipment, plus the benefit of being able to run your equipment on either mainline, this might be a good alternative. Remember, however, that you need to bring enough bridge tracks (4 per module), and if you plan to mix these corners with the conventional compact corners, you need to bring two corners with you.


A Compact Loop

We discovered the return loop module to be one of the handiest of all special modules. Two return loops permit a continuous run of any length, depending on the number of straight sections added in between. Four corner modules are not needed in this case.

Flexibility Adds to Uses

Construction is Easy Track Installation Might be Tricky

Wiring Tips

Variations on a Return Loop

As shown in the illustrations above and below, a smal yard can be formed with an elongated O-31 return loop. The siding shown branching from the mainline in the set on the left could be created using an O-72 turnout, or one of the new Lionel O-31 turnouts with the detachable half-curve section. The one on the right also provides reversing capabilities, plus a run-around track for the locomotives.


Packer O-42 Return Loop

by Howard Packer

Both the compact and extended compact loops have some problems with some equipment. Trains made up of cars with pre-MPC trucks sometimes fall over to the inside as they go around the loop, especially if they are stopped on the curve and then re-started. If the operator's attention is diverted and a train moves too fast through the loop, the engine and heavy cars may find their way to the floor.

Compromising With O-42 Track

Wiring the Modules Extending the Loop THE "T" MODULE

A module that lends itself to many flexible track plans is the T-module.

For example, if you want a staging yard, a yard for extensive switching activity, or an engine service area, the T-module placed somewhere in the layout will lead to it. This can lead into or out of a rectangle, or if you're using two return loops, in a "water-wings" arrangement. It can be made to lead off to either side.

By placing a return loop at the end of whatever tracks the T-module leads to, you can set up an alternate route for your trains. Your imagination can conjure other uses.


We'll leave the construction up to you. You can choose our lightweight plywood method, the heavier construction, or some design of your own. And you can use bolt-on, folding, or tubular legs. But whatever construction, these plans require a module at least 30" wide by four feet long, one of our standard sizes.

Crescent Model Railroaders

One club that has taken the Tracker module standard further is Crescent Model Railroaders. They have added a third mainline down between the main and secondary, and have substituted Gargraves track for standard tubular. They have also adopted a larger corner module design. More information can be found at the club's website which is linked above and on the Angels Gate Hi-Railers web page.


The original standards call for Lionel Standard O-compatible track (Lionel or K-Line). However, with the advent of the new Atlas-O solid rail track, MTH Real Trax, and MTH ScaleTrax, the tubular requiment has probably long passed. You should build to the standards chosen by your particular operating group and should have plenty of adapter pieces should you link up with other grops.

By changing dimensions slightly, you can use O-42 turnouts, such as those made by K-Line (Editor's note: Watch for inside clearance problems when using longer equipment through K-Line turnouts.). If you want to go the O-72 route, you'll need to follow different dimensions and a different design, such as was done by Woody Gillis in his T-modules.

The dimensions shown are approximate, so you may have to improvise a little here and there. For Howard's plan you'll need two full sections of O-42 curve, plus part of another one, and the track will end at the edge of the 30" width.

The front track ends the specified 5" from each end of the module. You provide one 5" and one 10" bridge track to connect to the module at one end of yours; the person at the other end should have similar bridge tracks to connect with your module.

The second track leaves an odd dimension between the turnout and the module edge. Bridge this with a section that length, ending your track at the module edge, plus a separate 5" piece to complete the connection to the track on the next module. The preferred method is to combine both of thes lengths in one piece of track, which would eliminate the shorter section, reserving the short section to match up with "non-bridge" modules..

  • Introduction
  • Simple Standards
  • What's in This Manual?
  • Section One: Module Construction
  • Section Two: Track
  • Section Three" Electrical
  • Section Four: Decoration and Scenery



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