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A crash bar (also known as a panic exit device, panic bar, or bump bar) [1] [2] is a type of door opening mechanism which allows users to open a door by pushing a bar. While originally conceived as a way to prevent crowd crushing in an emergency, crash bars are now used as the primary door opening mechanism in many commercial buildings.
There are two types: [1] A 'push to make' switch allows electricity to flow between its two contacts when held in. When the button is released, the circuit is broken. This type of switch is also known as a Normally Open (NO) Switch. (Examples: doorbell, computer case power switch, calculator buttons, individual keys on a keyboard)
The mechanism may be mounted near the floor, at the upper corner of the open door, or at any convenient height along the latch edge (away from the hinged edge). A steel plate, often mounted on a ball joint or swivel joint, is attached to the door so that it can contact the electromagnet when the door is fully opened.
However, an electric strike's ramped surface can, upon command, pivot out of the way when the lock on the door is in the locked position and the door is opened, allowing a user to pull/push the door to open it without operating the mechanical lock or using a mechanical key.
A lever tumbler lock is a type of lock that uses a set of levers to prevent the bolt from moving in the lock. [1] In the simplest form of these, lifting the tumbler above a certain height will allow the bolt to slide past. The number of levers may vary, but is usually an odd number for a lock that can be opened from each side of the door in ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 5 February 2025. Device to open or close door Various examples of door handles throughout history A door handle or doorknob is a handle used to open or close a door. Door handles can be found on all types of doors including: exterior doors of residential and commercial buildings, internal doors, cupboard ...
The first known example of a tumbler lock was found in the ruins of the Palace of Khorsabad built by king Sargon II (721–705 BC.) in Iraq. [1] Basic principles of the pin tumbler lock may date as far back as 2000 BC in Egypt; the lock consisted of a wooden post affixed to the door and a horizontal bolt that slid into the post.
The term "warded lock" refers to the lock mechanism, while the term "mortise lock" refers to the bolt location. Warded locks contain a series of static obstructions, or wards, within the lock box; only a key with cutouts to match the obstructions will be able to turn freely in the lock and open the latch. [4]