Lenz Reverse Loop Kit  
    

Figure 1: Basic Reversing Loop

• The only way to prevent this short circuit is to insulate both sides of the track. A single two-rail gap is not enough, since a passing engine will short the rail through the electrical pick-up on both sides of the gap. Therefore, the track has to be gapped on both sides of the reversing loop. One still has to ensure that the rails are not short circuited upon entry or exit of the reverse loop.
• Usually, the polarity is selected such that there is no short circuit upon entry into the loop. While the train is in the loop, the polarity is changed, so that there is no short circuit at the exit of the loop.
• On conventional layouts, this leads to a problem: Changing the polarity in the reversing loop will change the direction of the train, since it is dependent on the polarity. Therefore, the direction has to be changed at the power pack, too, so that the train keeps moving in the same direction. In any case, the train has to be stopped while traversing the loop.
• On NMRA DCC digitally operated layouts, the direction of the train is independent from the polarity on the track, therefore, the polarity of the reversing loop can be changed without stopping the train or changing it's direction.