Hi Don,
ok, now I know what you mean. Yes, this lock-slide was used to couple direction switches of each armature together, so when the E-Motor was klar, both armatures were powered in the same way. When one armature was damaged, the lock-slide was removed, respective switch was set in the Aus (middle) position, and the other switch could be operated independently.
However, this lock-slide was not coupled with Feldschalters, and I think that these Feldschalters were used during normal operation (not in case of damaged armature). I will post more details soon.
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Regards
Maciek