The locomotive(s) enter the loop from either direction, it does not matter which way.
The DPDT switch controls the power polarity to the insulated section shown at the top of the drawing. This switch should be thrown to the same polarity as the power pack prior to the locomotive entering this area.
Once in the insulated section, the throttle is closed. This section should be longer than any combination of locomotives you plan to run.
The direction switch is changed on the power pack. The polarity of the entire layout is now changed.
The DPDT toggle is also changed.The polarity of the insulated section is changed to match the layout.
Turn the throttle up and proceed through the loop.
