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 order to provide symmetry. A minimum number of levers may be specified to provide an anticipated level of security .
"Double acting" lever tumbler locks were invented in 1778 by Robert Barron of England. [2] [3] These required the lever to be lifted to a certain height by having a slot cut in the lever, so lifting the lever too far was as bad as not lifting the lever far enough. This type of lock is still used today, on doors in Europe, Africa, South America and some other parts of the world.
The lock is made up of levers (usually made out of non-ferrous metals). Each lever needs to be lifted to a specific height by the key in order for the locking bolt to move. [1] Typically, the belly of the lever is cut away to various depths to provide different combinations, or the gate is cut in a different location, to provide differs. A lever will have pockets (or gates) through which the bolt stump (or post or fence) moves during unlocking. [1]
There has not always been universal agreement about which variants of the basic design merit the terms "lever lock" or "detainer lock" or both. [4] [5] [6] [7] Some authors use the term "detainer lock" to refer specifically to variants where the gates are "open" (i.e. at the edge of the lever), rather than "closed" (i.e. entirely surrounded by the lever). [8] [9]
Lever locks generally use a bitted key. Some locks used on safes use a double-bitted key, as do some door locks of a type often used in Southern and Eastern Europe.
A three-lever lock is a common type of lever lock, but is generally used for low security applications such as internal doors [10] as their tolerances are much lower (there are fewer combinations of key available, so they are likely to unlock doors they shouldn't).
A five-lever lock is often required for home insurance and often recommended by the police for home security. [11] There are various grades but the current British Standard (BS3621:2007) is usually required for insurance purposes. Locksmith Valerie Olifent states that, "The doors of many historic churches still carry an old wooden lock although often you find that a modern 5-lever mortice lock has been installed alongside it to meet insurance requirements." [12] BS3621:2007 requires a bolt throw of 20 mm rather than the 14 mm of the earlier British Standard.
Most BS3621 locks have anti-pick devices built in to reduce the chance of lock picking, along with hardened bolts and anti-drill plates to reduce risk of physical attack.
 |
Lever tumbler locks can be picked with a tool called a curtain pick which is inserted into the keyway of the lock, and a force is applied to the locking bolt. The pick is then used to lift each lever inside the lock to the correct height so that the locking bolt can pass.
Higher security lever locks (such as the five-lever) usually have notches cut into the levers. These catch the locking bolt and prevent it from moving if picking is attempted (similar to the security pins in a pin tumbler lock).
The Chubb detector lock is a variation of the lever lock which was designed to detect and prevent picking attempts.
Lever locks can be drilled, but usually a template or stencil is required to mark the drilling point, as the lock mechanism is commonly mortised into the door and so it is harder to determine the point at which to drill.
Locksmithing is the science and art of making and defeating locks. Locksmithing is a traditional trade and in many countries requires completion of an apprenticeship. The level of formal education legally required varies from country to country from none at all, to a simple training certificate awarded by an employer, to a full diploma from an engineering college, in addition to time spent working as an apprentice.
Lock picking is the practice of unlocking a lock by manipulating the components of the lock device without the original key.
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 disc tumbler or disc detainer lock is a lock composed of slotted rotating detainer discs. The lock was invented by Finnish founder of Abloy, Emil Henriksson (1886–1959) in 1907 and first manufactured under the Abloy brand in 1918.
A combination lock is a type of locking device in which a sequence of symbols, usually numbers, is used to open the lock. The sequence may be entered using a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed symbols which directly interact with the locking mechanism, or through an electronic or mechanical keypad. Types range from inexpensive three-digit luggage locks to high-security safes. Unlike ordinary padlocks, combination locks do not use keys.
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 Chubb detector lock is a lever tumbler lock with an integral security feature, a re-locking device, which frustrates unauthorised access attempts and indicates to the lock's owner that it has been interfered with. When someone tries to pick the lock or to open it using the wrong key, the lock is designed to jam in a locked state until either a special regulator key or the original key is inserted and turned in a different direction. This alerts the owner to the fact that the lock has been tampered with.
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 rotary combination lock is a lock commonly used to secure safes and as an unkeyed padlock mechanism. This type of locking mechanism consists of a single dial which must be rotated left and right in a certain combination in order to open the lock.
Padlocks are portable locks usually with a shackle that may be passed through an opening to prevent use, theft, vandalism or harm.
Bitting is the depth of key cuts on a cylinder key for a pin tumbler lock, often expressed as a number. Bitting also refers to the combination of key cuts on a bit key for a warded lock or lever tumbler lock.
A skeleton key is a type of master key in which the serrated edge has been removed in such a way that it can open numerous locks, most commonly the warded lock. The term derives from the fact that the key has been reduced to its essential parts.
Rekeying a lock is replacing the old lock pins with new lock pins.
A master key operates a set of several locks. Usually, there is nothing different about the key. The differences are in the locks the key will operate. These master-keyed locks are configured to operate with two, or more, different keys: one specific to each lock, which cannot operate any of the others in the set, and the master key, which operates all the locks in the set. Locks that have master keys have a second set of the mechanism used to operate them that is identical to all of the others in the set of locks. For example, master keyed pin tumbler locks often have two shear points at each pin position, one for the change key and one for the master key. A far more secure system has two cylinders in each lock, one for the change key and one for the master key.
Lock bumping is a lock picking technique for opening a pin tumbler lock using a specially crafted bump key, rapping key or 999 key. A bump key must correspond to the target lock in order to function correctly.
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 protector lock has referred to two unrelated lock designs, one invented in the 1850s by Alfred Hobbs, the other in 1874 by Theodor Kromer.
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.
This is a glossary of locksmithing terms.
Lever tumbler locks are built and operate much differently than the conventional and more popular pin tumbler lock. Although they have their place in high-security applications, such as safe deposit boxes with a double-set tumbler design, they are used mostly for applications that allow a more lenient state of security. Today, they are used mostly for mailboxes, luggage, lockers, and other light security applications...
Their biggest disadvantage, however, is that they do not allow for as many master-key combinations as pin tumbler locks.
In a basic, fixed, lever tumbler lock design, the entire lock is enclosed in a case... The simple lever lock has three or more lever tumblers that pivot on a post and are pushed into the 'locking' position by springs, which are bound against the case and attached to the tail end of each lever tumbler. When the proper key is inserted into the lock and turned, it raises each tumbler to the point where the fence of the lock's bolt can clear the obstruction or face of each tumbler, which also blocks each tumbler's gate. When all the tumblers are in this position, the fence can be thrown through each tumbler's gate, which pushes the bolt into the retracted position.
In other lever lock designs, a post is connected directly to the bolt. With the lever tumbler lock, when the tumblers are raised to the proper position the post of the bolt will pass through the front gating to the rear gating and hold the bolt in the retracted position.
There are two different ways that the lever lock bolt can be thrown. In some lever locks, the end, or uncut, portion of the key that acts as a bolt throw will make contact with a bolt throw notch cut into the bolt. The other method is to use a trunnion with a talon built on the bottom of it. In both instances, when the key is turned contact is made with the bolt throw notch of the bolt, which allows it to be retracted.
Different types of lever locks have different tumbler designs. [Simple] lever [tumblers] with one gate [rely] on the obstruction built onto the face or front of the tumbler and its tumbler trap to lock the bolt into either the locked or unlocked position. [Other types] of lever tumbler [use] a front and rear gate to trap the bolt into either position.
Some lever tumblers have serrated saddles, or bellies, others have false gates. These varying designs make it more difficult to pick a lever tumbler lock. Lever tumblers with false gates usually are reserved for high-security units.
2 & 3 lever mortice locks are generally only recommended for use on internal doors as they do not provide adequate levels of security externally
| Fundamental concepts |  | |
|---|---|---|
| Components and hardware | ||
| Keys | ||
| Mechanical locks | ||
| Electronic locks | ||
| Other lock types | ||
| Lock picking | ||
| Security alarms |
| |
| Miscellaneous | ||
