A
lock is a device that prevents a door or other
objects from being opened or moved. People use
locks to help protect themselves and guard their
property against misuse, damage or theft.
All door locks have some type of
bolt that prevents the door from being opened.
In most door locks, the bolt slides into a metal
plate in the doorframe. A long narrow piece of
metal called a cam controls the movement of the
bolt. The cam is fastened to a cylinder-locking
mechanism in the door.
When a person inserts the proper
key in a door lock, the grooves of the key force
the metal pins or plates called tumblers to align.
When the tumblers are in line, the key is free
to turn and activate the cam. The cam moves the
bolt between the door and the doorframe.
Deadbolts are the most secure type
of bolt. Most of them are mounted into a steel
frame on the inside surface of a door.
The deadbolts lock with a key on
the outside and by turning a small knob on the
inside. Other deadbolts are set in the door and
controlled by the cam. They are ‘dead’ because
they cannot be pried open.
NOTE: The earliest locks
were made over 4,000 years ago by the ancient
Egyptians. Wooden locks have been found in the
Egyptian pyramids! |
