I just came up with a trap/execution method I plan to use in my next fortress: The Perpetual Wave-Motion Dwarven Atom Smasher (PW-MDAS). It's simple: A 1-tile wide, n-tiles long drawbridge that is triggered by a pressure plate. When it smashes down, it triggers another pressure plate, which triggers a second bridge next to it, and so on, down a hallway until the chain is deemed long enough, in which case the pressure plate the last bridge activates the first bridge again, creating a perpetual-motion wave of DAS.
W : wall
= : channel
# : bridge (raised)
* : pressure plate
WWW
####
====
****
WWW
First bridge activates first pressure plate, which lowers the second bridge, which activates the second plate. The second plate activates the third bridge, which lowers, activating the third plate. This plate lowers the fourth bridge, which hits the fourth plate, which activates the first bridge again.
Caveats:
- Bridges need to auto-retract.
--Perhaps by adding another channel line, then another line of pressure plates, which are linked to the bridge directly across the walkway? See Diagram 2.
- Pressure plates need to be DAS-proof.
DIAGRAM 2:
W
##
==
13
==
24
W
First bridge is lowered, activating plates 1 and 2. Plate 1 causes the second bridge to lower, while Plate 2 causes the first bridge to retract. Bridge 2 has the same kind of setup.
Pros:
- True perpetual motion.
- One activation, no resets.
Cons:
- Plates may not be DAS-proof.
- Dangerous to build linkages.