tying a gear to a lever makes the gear enable or disable, also gears dont "realign" themselves to levers, if you attach them while disabled you get a different result then attaching them enabled
i suggest we make it so you can add things to gears that get disabled or enabled depending on settings set like if with a pressure plate
being:
on trigger [enabled/disabled/toggle] (fire on the gear being enabled, disabled or on both)
on power is [MIN]/[MAX](fire on the gear being powered with a certain value of power, just as with weight or water pressure on pressure pads)
on powered [Y/N] (fire on this being powered enough to make it turn or not)
additionally this makes the following possible
lever to gear to door> lever is ON door is closed, lever is OFF door is opened
lever to door> lever is ON door is opened, lever is OFF door is closed
and many more, like computers or counters or intelligent fortress entrances (that respond on input, for example if an entrance hallway detects goblins in it with pressure plates, but no dwarves it locks it down and fills with magma, once its full it drains it again and waits a few moments for the magma to evaporate to open it again, if dwarves ARE present, the barracks to the sides of the hallway get there bridge "wall" lowered so any dwarf training in the barracks will instantly attack the goblins)
or even intelligent power systems, if for some reason power fails partially (the building destroyer enemy did it lololo) it will disable secondary systems (the milling room) so that all power goes to the pumps keeping your basement from flooding, or your well filled
all of the examples above are far fetched, but it would be very possible and relatively easy once you work out the layout of the system (what to connect to what and how) and would allow for SO MUCH FUN AND AWESOME MEGAPROJECTS
imagine 8 bit computer, or even a DECIMAL 8 bit computer (if you can set power amounts to a system, you can add decimal value bits (so in stead of 1 and 0, 0 to 9 in 1 bit... or much much more)
conclusion: basically if we expand the gears like suggested above, we can make pretty much anything with mechanisms and power... anything else needed for a flexible system is already in the game