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A portcullis (from Old French porte coleice 'sliding gate') is a heavy, vertically closing gate typically found in medieval fortifications. [1] A portcullis gate is constructed of a latticed grille , made of wood or metal or both, which slides down grooves inset within each jamb of the gateway.
Bar gates, especially manually operated ones, are often counterweighted to allow easier manual control. [7] Bar gates are frequently paired end to end or closely offset to block traffic in both directions. Some bar gates also have a second arm which hangs 30 to 40 cm below the upper arm when lowered to increase approach visibility.
A swing bridge (or swing span bridge) is a movable bridge that can be rotated horizontally around a vertical axis. It has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then pivot horizontally as shown in the animated illustration to the right.
Example - a maximum of 400N of force can be applied in the last 50, 300 and 500 mm of travel of a gate, after the initial impact the force must drop to 150N within 0.75 of a second and reduce to 25N within 5 seconds.
A drawbar is a defensive implement used to secure a door or gate in a medieval or Early Modern building such as a castle, [1] [2] but also churches and townhouses. When drawn across the full length of the door, it prevents the door or gate from being opened. To open the door or gate, the drawbar is pushed into a drawbar slot in the wall.