40d:Pressure plate

Pressure plates work somewhat like levers, but instead of being actively toggled, they're activated by the weight of something on them.

Pressure plates are not configured during use, but upon placement. While placing a pressure plate, you can configure it to trigger when the following things are on it:

• Water/Magma - choose minimum and maximum levels
• Creatures - choose minimum and maximum size; creatures of the size selected will be listed as example. You can pick whether your own citizens will trigger the plate or not.

Pressure plates default to toggleable, where they send an On signal when the determined weight is upon them and send an Off signal when it's released. Pressing o will change them to one-use mode, where upon being activated, they do their work and cease to operate altogether.

Pressure plates can be linked to all the same objects levers can. The effects are listed in the Lever page.

A toggleable trap may prove useless when there is a large amount of invaders walking back and forth over it, as there will not be enough time for it to activate before it is switched again. Berserk dwarves will set off pressure plates.

It is possible to hook a toggleable pressure plate up to a device which makes its effect permanent until a lever is flipped. One way to do that is to build a water-sensing pressure plate in a 1x1 room, link that to your trap (a drawbridge, for example), build a hatch above it, link the hatch to the original pressure plate outside, and then put water on the hatch. When an enemy steps on the pressure plate, the hatch opens, the water falls onto the other pressure plate, and it raises the drawbridge. (To make it resettable, use pumps controlled by a lever or by dwarf-power to move the water back to where it started.)

Shortcut b-T-p

Components used: Mechanism

Common procedures

Closing a floodgate when submerged

For this example, say we want to close a floodgate when a reservoir reaches a depth of 5.

• Build the pressure plate, set to activate under water (w) from 0 (a, s) to 4 (z, x). Set it to reset (o).
• Place the floodgate
• Connect a lever to the floodgate, and open it.
• Optionally remove the lever.
• Connect the pressure plate to the floodgate.
• Allow the pressure plate to be submerged.

The floodgate should close a few seconds after the water reaches a depth of 5 or more, and open again when the depth falls to 4 or less.

It's worth noting that the reaction time of the pressure plate-floodgate system is quite large - the reservoir may overflow before the floodgate shuts. In order to prevent this (for example, when building a well filled from a river or brook), build a large run-off pool. This allows the gate enough time to close, and will buffer any overflow. In my head, this made sense.

V · T · E Buildings
Workshops • Furnaces
Rooms	Barracks • Bedroom • Dining room • Jail • Meeting hall • Office • Sculpture garden • Tomb • Zoo
Furniture	Animal trap • Anvil • Armor stand • Bed • Bin • Bucket • Cabinet • Cage • Coffin • Container • Restraint • Seat • Statue • Table • Weapon rack
Access	Door • Floodgate • Bars • Grate • Floor hatch • Bridge • Road • Window
Constructions	Fortification • Floor • Stairs • Ramp • Wall
Machine & Trap parts	Axle • Gear assembly • Millstone • Screw pump • Water wheel • Windmill • Lever • Pressure plate • Trap • Support
Other Buildings	Archery target • Kennel • Shop • Siege engine • Trade depot • Wagon • Well
Related Articles	Design strategies • Bedroom design • Cave-in • Computing • Furniture industry