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Tuesday, May 21, 2013

A large scale stub switch idea

My upcoming project will be in G scale, and for this, I really want to do some good, old-fashioned hand laid track.  Most G scale track comes in .332 and .250 heights, which means that the track is 1/3" and 1/4" high. in 1:20.3. 1:1 measurements of  these profiles are 6.7" and 5.1" in height.  This equates to 130 lb and 85lb rail in the real world.

Narrow gauge railroads and industrial railroads, as well as lines prior to 1900 often had smaller profiles and weights usually about 80lbs or less.  So code 250 would work on the main track age of a narrow gauge model railroad, but I am modeling a branch line, specifically the end of a spur to a mine.  Therefore, the profile must be even smaller.

Atlas makes great O scale track that I believe is code 148 and I believe that Atlas 3 rail track is about code 215.  This profile can model in 1:20.3 scale track that would really be  3.1 and 4.3 inches in height.  This equates to 30 lb and 65 lb rail.  30lb would only be used on the smallest, most worn, and seldom used sidings.  60lb rail would be used for the branch lines and most important spurs.

On a different, but somewhat related topic, I've came up with a good idea for turnouts on the next project layout.  The problem with turnouts on toy trains is that the electric current running through the rails short circuits at the frog.  Therefore, most turnouts have a large, insulating gap which keeps the wheels from bridging opposing currents.  On small locos, this gap can be enough to stall the engine, which is unacceptable for us modelers.  The most well known solution is 'live frog' turnouts, where a circuit board powers the frog, and changes the current in the frog depending on how the points are thrown.  Outdoors, this solution is possible, but it costs significantly more than insulated frogs, and is less reliable due to the fragile circuit board.  Indoors, this is a better option, but the price is about the same as having the turnout outdoors.

My solution is to decrease the insulated portions of the frog, thus making the turnout more efficient.  Below is a diagram of my idea:
First, for simplicity, I drew a stub switch above.  The main difference between a turnout and a stub switch is that a stub switch has two parallel rails which pivot to align with one of two sets of diverging rails.  A turnout has tapered points which move back and forth between two outside rails, one goes straight, while the other diverges.

The frog is the most complicated part of the turnout, and must be as accurately cut as possible.  Add to that the cutting and insulating needed for a frog, and that complicates things further.  Above is my frog design.  Instead of one large insulated frog, the flange ways and guard rails are powered, with only two rail portions and the central triangle being insulated.  The insulated rail heads are in black, while the insulated flange ways are in gray.  Red and green represent opposing polarities.

This arrangement allows the wheel flanges to "ground out" on the flat surface of the flange way.  The flange of the wheel is made of metal and picks up the current from the flange way, thus keeping power to the motor.

Please keep in mind that this is UNTESTED, therefore I don't know for sure if this arrangement will work as planned.  I will make a test switch to make sure that everything works in the near future.  I'll get back to this topic in a few days.

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