Right then. The main entrance to my fortress is a pair of bridges over a chasm that lift in either direction, blocking both tunnels ( to dissuade any of the locals from taking advantage of a siege ), and a retracting bridge that when /not/ retracted, acts as a cap to block the wagon sized hole that opens onto the overland map.
The retracing bridge is linked to two levers - one lever that solely controls the retracting bridge, and another that /should/ control the raising bridges over the chasm And the retracting bridge. Plan was, to use the first lever to retract the 'cap' on the entrance, and then in times of siege, throw the second one, causing the retracting bridge to extend and cover the entrance while the raising bridges blocked the chasm off on both sides.
It doesn't seem to have worked.
Am I doing something wrong?
As is, the lever dedicated to the retracting bridge works fine, but the lever connected to all three bridges only controls the cap when it's doing the same as the bridges over the chasm - that is, it will only extend the 'cap' when the chasm bridges would lower, and will only retract it when they would raise. It was my assumption that pulling the lever just made the bridges change from whatever state they were currently in to the other.. not whatever it's doing here.