Science Fair Project Encyclopedia
Drawbridge
A drawbridge is a type of movable bridge typically associated with the entrance of a castle, but the term is also used to describe modern bascule bridges and lift bridges.
The most common type of drawbridge consists of a wooden platform with one fixed side (normally with a hinge), and the other side attached to the wall it is raised against by rope or chains. Pulling on the chain raises the bridge.
In the middle ages drawbridges where often used to allow or deny access across a moat or ditch.
Now, with cars and trains in need of crossing small waterways without blocking boats from passing drawbridges have a more peaceful reason for their existence.
See also
03-10-2013 05:06:04
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details