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  • Handlaying N-Scale Track Part: 2

    The bridle bar on a prototype turnout is quite complicated with all the angle brackets and supports. There are numerous adjustment mechanisms, too.
    Model Railroading - May 1996 - Page 13 Model Railroading - May 1996 - Page 14

     

    by Doug Geiger. MMR

    This month's article continues our discussion of handlaying N scale code 40 rail as we scratchbuild code 40 turnouts in N-scale. Last month, general tracklaying was covered. Beginning this month and next, we cover turnouts. Although there are several varieties of turnouts, most can be built using these procedures. The most common type is the normal turnout. There are curved turnouts, wye turnouts, gauntlet turnouts, single-and double-slip switches and three-way turnouts. All are variations of the normal type. On most prototype railroads, a turnout is known as a switch. But there are some that call it a turnout. In model railroading, "turnout" is preferred to avoid confusion with an electrical switch.

    Figure I describes the vocabulary of a typical turnout. This diagram shows the split switch which is the most common turnout type. However, there are also two other distinct forms of turnouts: stub and tongue. The stub switch has no points. Instead, the approach rails are bent to connect with the closure rails. This type of turnout gave maintenance headaches when trying to keep the approach rails aligned. Derailments were common at medium speeds (over 2S mph). Stub turnouts became extinct early in the 1900s, except on many narrow gauge lines. None have been found on mainline U.S. railroads since 1920. The other type of turnout is the single-point or tongue switch. These were most common in trolley or street-car railroads. There is only one movable point in a tongue switch. The point along side the straight stock rail is not present. It is replaced with a flange way guid only. These turnouts usually have very sharp curvatures. Again, slow-speed operation is necessary through a tongue switch. Constructing either of these two types of turnouts are not covered in this article. Further turnout discussions will always refer to the common split switch.

     

    In modeling, the rigid frog turnout is the most common. Here is an example of a prototype rigid frog. Note the two guard rails and all the bolts, spacers and support brackets.
    Model Railroading - May 1996 - Page 15 Model Railroading - May 1996 - Page 16

     

    The two primary components of a turnout are the points and frog. The frog was named very early since it is in this area of a turnout that the wheels can "jump" or "hop" over the intersecting rail. The points show the way for the train to take either the normal route or the diverging route. The fundamental measure of a turnout is the frog number. This indicates the amount of divergence caused by the angle of the two intersecting rails at the frog. The number simply measures the distance at which a unit measure becomes the separation distance. For example, a #10 frog diverts the rails 1' at 10' from the point of the frog. A #16 frog diverges 1' at 16'. The frog number determines the turnout number.

    Most model railroads use #4 or #6 turnouts. However, the prototype rarely uses a turnout this sharp. They primarily use #lOs, #12s and larger. For high-speed mainlines (70 mph or more), turnouts must be #20s or larger. A #22 turnout is not uncommon! In most scales, these big turnouts are impractical. For example, in HO scale, a #20 turnout would require 21 1/2" from the point to the frog ! But in N scale, these big turnouts can be used without dwarfing their surroundings. A #20 turnout in Nscale would only require 11 3/4".

    Figure I shows a rigid frog type. This has been common on most railroads, especially on low-speed tracks. These were originally made from separate rail segments. Now, most are cast as a single component. This frog requires two guard rails alongside the stock rails to keep the wheels from picking a route not described by the points. Other frog types are self-guarding (uses no separate guard rails), spring rail (moving wing rails) and moveable (hinged frog rails). For most modeling, avoid these three types as they are difficult to achieve with reliability.

     

    This prototypically scaled N scale turnout is located on the author's East Portal Moffat Tunnel module.
    Model Railroading - May 1996 - Page 17

     

    Note also the bridle bar or the connection between the points. This bar or angle iron is connected only to the points and not the stock rails. Also, the wing rails and guard rails have a slight bend at the ends to help ease the wheel flanges into the directing rails. The point heel is the location where the points are hinged to the closure rails. In the prototype, various anchors and rubber blocks are used to keep the alignment of all the various rail parts in a turnout. Grease is usually abundant around the toe and heel of the points. Grease marks are an often-neglected detail on most layouts. For realism, the tops of the guard rails and wing rails should be left rusty. Practically, they usually get cleaned along with the rest of the track on our model railroads.

    For some modelers, a template aids with tie placement under a turnout. For small turnouts, like #4s or #5s, the variation in tie locations is not critical. But for the big turnouts, templates are critical. Figure 2 supplies templates for three sizes of big right-hand turnouts, #10, #12 and a #14. These templates have been developed using the American Railway Engineering Association (AREA) standards for turnouts. The templates are full-size for N scale and can easily be copied. Copy the page onto a transparency, flip the transparency over and copy again. This will provide you with left-hand turnouts. They have been developed using Micro Engineering ties and their code 40 rail. Part III next month will use these templates extensively.

    Along with the tie templates is Figure 3 which illustrates the locations for electrically gapping the turnout. Again, Part III will explain this diagram. Figure 4 will also be useful when constructing the turnout next month. It shows several critical dimensions and positioning of the various rail pieces. The photos this month (Photos 10- 14) describe typical turnouts commonly found on the prototype. Although located on the Burlington Northern and Union Pacific, they are typical of modern turnouts duplicated by the thousands all over North American railroads of today.

    For part 1 click here

    For part 3 click here

     

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