they are the reversing sections made by LGB (when used as a pair ie 1015t and 1015 U) _
one section has a diode board -the idea is that in a fully isolated dogbone return loop-where there normally would be a problem of +positive meeting - negative on the loop
these pieces do not have relay-the simply have a cover over the board inside with separate poles to wire each leg of the isolation track-one of the pieces has its own board built in with electrical current direction controlling diodes
-the loop is isolated by using one of each at opposite ends of the return loop
-the diodes allow a single travel direction in to the loop by the train
-the loco enters the loop -the 1015t allows current to feed into the isolated loop but doesn't allow this from the 1015U-
then when you slow, stop and reverse the polarity from the trafo-the other set of diodes ) allows current to flow into the isolated portion-the loco continues and the issue of wiring and other matters associated with a reversing loop are eliminated-
these are actually rather pricey little sets
very very handy-but require the driver to slow and stop and reverse every time the reverse loop is entered *
*however if one uses a magnet and relay -then while the loco is in the loop a relay controlling polarity could be used, and with a quick change of polarity the train will continue on without a slow and stop (well except for a split second during the change over)
as noted they have a set of connector poles under the covers which can be altered to other functions as well-they can feed power to on side or the other or both, and, if i recall rightly, each individual rail as well-so these could be used for sidings , passing tracks, etc
they could even allow an engine to enter a siding , and be 'parked' simply by reversing the polarity of the throttle and allowing another engine to run in the opposite direction
of for an engine to enter a stub and stall on the stub until the throttle was reversed (using the diode feature)
as i recall one of the sections-1015 t or 1015u-cant tell you which -has the diodes-the other is simply a rail isolator-without diodes-
as LGB switches power both legs this works -the power feed remains the same leg of the point-but varies the 'gate' -ie power supplied via the diodes-
this may be unintelligible as ive described it
if so ask and ill muddle on
