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A deadbolt or deadlock is a type of lock morticed into a wooden door where a bolt is thrown into the door frame, using a key from either side, to secure the door. [1] It is distinct from a spring bolt lock because a deadbolt can only be opened by a key or handle. The more common spring bolt lock uses a spring to hold the bolt in place, allowing retraction by applying force to the bolt itself. [2] A deadbolt can therefore make a door more resistant to entry without the correct key, as well as make the door more resistant to forced entry.[ citation needed ] A deadbolt is often used to complement a spring-bolt lock on an entry door to a building.
A deadlock, if it is cylinder operated, may be either single cylinder or double cylinder. A single cylinder deadlock will accept a key on one side of the lock, but is operated by a twist knob on the other side. Double cylinder locks will accept a key on both sides and therefore do not require (and often do not have) any twist knob. This prevents unwanted unlocking of the door by forced access to the interior twist knob (via a nearby window, for example). Double cylinder locks are sometimes banned from areas because they can be difficult to open from the inside and violate fire safety regulations. Some lock manufacturers also have a "lockable" knob: a key is always needed on one side (usually external), and a twist knob can be used on the other (internal), unless a button has been pressed, in which case a key is also needed on the internal side. [3]
A variant of the standard deadbolt is the vertical deadbolt, invented by Samuel Segal. Vertical deadbolts resist jimmying, in which an intruder inserts a crowbar between the door and the jamb and attempts to prise the bolt out of the door.
Other types of deadbolts include:
The double cylinder design raises a safety issue. In the event of a fire, occupants will be prevented from escaping through double-cylinder locked doors unless the correct key is used. This is an avoidable cause of death in house fires.[ citation needed ] [4] The risk can be mitigated by locking the deadlock only when there are no occupants inside the building, or leaving the key near the keyhole. Some fire departments suggest putting the key on a small nail or screw near the door at floor level, since the cleanest air is at floor level and one may be crawling to get to the exit, thus placing the key where it is easiest to find.
Note that single cylinder dead locks (with an unlocked twist mechanism on the inside of the door) do not have this problem, and therefore are most commonly used on fire exits. Some areas have fire safety codes that do not allow a locked exit. [5] [6]
A warded lock is a type of lock that uses a set of obstructions, or wards, to prevent the lock from opening unless the correct key is inserted. The correct key has notches or slots corresponding to the obstructions in the lock, allowing it to rotate freely inside the lock.
The pin tumbler lock, also known as the Yale lock after the inventor of the modern version, is a lock mechanism that uses pins of varying lengths to prevent the lock from opening without the correct key.
A lock is a mechanical or electronic fastening device that is released by a physical object, by supplying secret information, by a combination thereof, or it may only be able to be opened from one side, such as a door chain.
A lever tumbler lock is a type of lock that uses a set of levers to prevent the bolt from moving in the lock. In the simplest form of these, lifting the tumbler above a certain height will allow the bolt to slide past.
A mortise lock is a lock that requires a pocket—the mortise—to be cut into the edge of the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortise locks are found on older buildings constructed before the advent of bored cylindrical locks, but they have recently become more common in commercial and upmarket residential construction in the United States. The design is widely used in domestic properties of all vintages in Europe.
A crash bar 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.
Door furniture or door hardware refers to any of the items that are attached to a door or a drawer to enhance its functionality or appearance.
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 doors and vehicle doors. There are many designs of door handle, depending on the appropriate use. A large number of handles, particularly for commercial and residential doors, incorporate latching or locking mechanisms or are manufactured to fit to standardised door locking or latching mechanisms.
A latch or catch is a type of mechanical fastener that joins two objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on the other mounting surface. Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.
A lock bypass is a technique in lockpicking, of defeating a lock through unlatching the underlying locking mechanism without operating the lock at all. It is commonly used on devices such as combination locks, where there is no natural access for a tool to reach the locking mechanism. Because the mechanism itself is not being manipulated, this could technically not be considered lockpicking at all. However, it does fall under the repertoire of techniques used to open locks. Lock bypass is one of the most important parts of locksmithing, especially with respect to public buildings which must be able to be opened from inside in case of fire, thus allowing the use of "letter box tools" among other techniques. Locks may be bypassed by a variety of other techniques including loiding, i.e. the "credit card" technique, against self-closing "latch systems."
An electronic lock is a locking device which operates by means of electric current. Electric locks are sometimes stand-alone with an electronic control assembly mounted directly to the lock. Electric locks may be connected to an access control system, the advantages of which include: key control, where keys can be added and removed without re-keying the lock cylinder; fine access control, where time and place are factors; and transaction logging, where activity is recorded. Electronic locks can also be remotely monitored and controlled, both to lock and to unlock.
An electric strike is an access control device used for door frames. It replaces the fixed strike faceplate often used with a latch. Like a fixed strike plate, it normally presents a ramped or beveled surface to the locking latch allowing the door to close and latch just like a fixed strike would. 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. After the door is opened past the keeper, the keeper returns to its standard position and re-locks when power is removed or applied, depending upon the strike's configuration.
A wafer tumbler lock is a type of lock that uses a set of flat wafers to prevent the lock from opening unless the correct key is inserted. This type of lock is similar to the pin tumbler lock and works on a similar principle. However, unlike the pin tumbler lock, where each pin consists of two or more pieces, each wafer in the lock is a single piece. The wafer tumbler lock is often incorrectly referred to as a disc tumbler lock, which uses an entirely different mechanism.
The term door security or door security gate may refer to any of a range of measures used to strengthen doors against door breaching, ram-raiding and lock picking, and prevent crimes such as burglary and home invasions. Door security is used in commercial and government buildings, as well as in residential settings.
A magnetic keyed lock or magnetic-coded lock is a locking mechanism whereby the key utilizes magnets as part of the locking and unlocking mechanism. Magnetic-coded locks encompass knob locks, cylinder locks, lever locks, and deadbolt locks as well as applications in other security devices.
An electromagnetic lock, magnetic lock, or maglock is a locking device that consists of an electromagnet and an armature plate.
A lockset is the hardware and components that make up the locking or latching mechanism that can usually be found on a door or other hinged object but can also include sliding doors and dividers. The components of a lockset can include the door handles, latch bolt, dead bolt, face plate, strike plate, escutcheon, thumbturn, push button, turn button, and other trim. The lockset and associated hardware typically defines a door's function and how a user could access the two adjacent spaces defined by the opening associated with the lockset.
A night latch is a lock that is fitted on the surface of a door; it is operated from the exterior side of the door by a key and from the interior side of the door by a knob.
An officer’s tool is a forcible entry device used by firefighters and other first responders. Officer’s tools are designed to completely remove cylindrical locks from doors without causing major structural damage, allowing for direct access to the internal locking mechanism.
This is a glossary of locksmithing terms.