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A mortise lock (also spelled mortice lock in
British English British English is the set of Variety (linguistics), varieties of the English language native to the United Kingdom, especially Great Britain. More narrowly, it can refer specifically to the English language in England, or, more broadly, to ...
) is a
lock Lock(s) or Locked may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainme ...
that requires a pocket—the mortise—to be cut into the edge of the
door A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide securit ...
or piece of
furniture Furniture refers to objects intended to support various human activities such as seating (e.g., Stool (seat), stools, chairs, and sofas), eating (table (furniture), tables), storing items, working, and sleeping (e.g., beds and hammocks). Furnitur ...
into which the lock is to be fitted. Mortise lock describes only a method of fitting the lock, and says nothing about the quality or key mechanism. In some parts of the world, mortise locks are found on older
building A building or edifice is an enclosed Structure#Load-bearing, structure with a roof, walls and window, windows, usually standing permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, a ...
s 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 properties of all ages in Europe.


History

Mortise locks have been used as part of door hardware systems in the US since the second quarter of the eighteenth century. In these early forms, the mortise lock mechanism was combined with a pull to open the unlocked door. Eventually, pulls were replaced by knobs. Until the mid-nineteenth century, mortise locks were only used in the most formal rooms in the most expensive houses. Other rooms used box locks or rim locks; in contrast with embedded mortise locks, the latch itself is in a self-contained unit that is attached to the surface of the door. Rim locks have been used in the United States since the early eighteenth century. An early example of the use of mortise locks in conjunction with rim locks within one house exists at
Thomas Jefferson Thomas Jefferson (, 1743July 4, 1826) was an American Founding Fathers of the United States, Founding Father and the third president of the United States from 1801 to 1809. He was the primary author of the United States Declaration of Indepe ...
's
Monticello Monticello ( ) was the primary residence and plantation of Thomas Jefferson, a Founding Father, author of the Declaration of Independence, and the third president of the United States. Jefferson began designing Monticello after inheriting l ...
. In 1805, Jefferson wrote to his
joiner Joinery is a part of woodworking that involves joining pieces of wood, engineered lumber, or synthetic substitutes (such as laminate), to produce more complex items. Some woodworking joints employ mechanical fasteners, bindings, or adhesives, ...
listing the locks he required for his home. While closets received rim locks, Jefferson ordered 26 mortise locks for use in the principal rooms. Depictions of available mortise lock hardware, including not only lock mechanisms themselves but also escutcheon plates and door pulls, were widely available in the early nineteenth century in trade catalogues. However, the locks were still expensive and difficult to obtain at this time. Jefferson ordered his locks from Paris. Similarly, mortise locks were used in primary rooms in 1819 at
Decatur House Decatur House is a historic house museum at 748 Jackson Place in Washington, D.C., the capital of the United States. It is named after its first owner and occupant, the naval officer Stephen Decatur Jr. Built in 1818, the house is located at ...
in Washington, DC while rim locks were used in closets and other secondary spaces. The mortise locks used at Monticello were
warded lock A warded lock (also called a ward 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 i ...
s. The term "warded lock" refers to the lock mechanism, while the term "mortise lock" refers to the lock method of fixing. 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. Warded locks were used in Europe from the Roman period onwards. Two English locksmiths, Robert Barron and Jeremiah Chubb, played a major role in creating modern
lever tumbler lock A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or '' fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load, and effort, the lever is ...
s. Chubb's lock was patented in 1818. Again, the term refers to the lock mechanism, so a lock can be both a mortise lock and a lever tumbler lock. In the modern lever tumbler lock, the key moves a series of levers that allow the bolt to move in the door. The next major innovation to mortise lock mechanisms came in 1865. Linus Yale, Jr.'s pin tumbler mortise cylinder lock used a cam on the end of the key cylinder to operate the bolt or latch. This innovation allowed keys to be shorter as they no longer had to reach all the way through a door. Pin tumbler locks are still the most common kind of mortise door lock used today.


Mechanism

Mortise locks may include a non-locking latch operated by a door handle. An upright two-bolt lock is termed a sash lock. The upright case was invented for the new design of glazed or part-glazed door — the 'sash door'. Sash doors have upright styles too narrow for the earlier horizontal lock case, in which the case is wider than it is tall. Most modern mortise door locks are now upright rather than horizontal. Upright latches should have lever handles, horizontal latches now usually have knob handles. A lock without a latch is termed a dead lock. Dead locks are commonly used as a secure backup to a sprung non-deadlocking latch, now often a pin tumbler rim latch.The type commonly called a "Yale" lock. Mortise latches, which might or might not be deadlocking, have also been made, but are now uncommon. Mortise locks have historically, and still commonly do, use lever locks as a mechanism. Some older mortise locks have used warded lock mechanisms. This has led to popular confusion, as the term "mortise lock" was usually used in reference to lever keys in traditional European terminology. In recent years the Euro cylinder lock has become common, using a pin tumbler lock in a mortise housing. The parts included in the typical US mortise lock installation are the lock body (the part installed ''inside'' the mortise cut-out in the door); the lock trim (which may be selected from any number of designs of
doorknob 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 building, residential and commercial buildings, internal doors, cupboard doors and vehic ...
s,
lever A lever is a simple machine consisting of a beam (structure), beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, l ...
s, handle sets and pulls); a
strike plate This is a glossary of locksmithing terms. Glossary References External links {{Locksmithing Locksmithing Locksmithing is the work of creating and bypassing lock ...
(or box keep), which lines and reinforces the cavity in the door jamb or frame into which the bolt fits; and the keyed cylinder which operates the locking/unlocking function of the lock body.


Selection and installation

The installation of a mortise lock can be undertaken by an average homeowner with a working knowledge of basic
woodworking Woodworking is the skill of making items from wood, and includes cabinetry, furniture making, wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first materials worked b ...
tools and methods. Many installation specialists such as carpenters use a dedicated mortising jig which makes precise cutting of the pocket a simple operation, but the subsequent installation of the external trim can still prove problematic if the installer is inexperienced. Although the installation of a mortise lock actually ''weakens'' the structure of the typical timber door, the embedded lock is typically stronger and more versatile than the newer bored cylindrical lock (or tubular lock) format, both in external trim, and functionality. Reinforcing plates can be bolted to the door surface over the mortise to strengthen the door. Whereas the newer mechanism lacks the physical volume and mechanical stability required for ornate and solid-cast knobs and levers, the mortise lock can accommodate a heavier
return spring Return may refer to: In business, economics, and finance * Return on investment (ROI), the financial gain after an expense. * Rate of return, the financial term for the profit or loss derived from an investment * Tax return, a blank document or t ...
and a more substantial internal mechanism. Mortise locks are available in a wide range of functional security configurations, and are widely installed in industrial, commercial, and institutional environments, and in Europe, domestic doors. Furthermore, a typical US mortise lock typically accepts a wide range of other standardized manufacturers' cylinders and accessories, allowing architectural and functional conformity with other lock hardware already on site. Manufacturers of mortise locks in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
include Accurate, Arrow, Baldwin, Best, Corbin Russwin, Emtek Products, Inc, Falcon, Penn, Schlage, Sargent, and
Yale Yale University is a private Ivy League research university in New Haven, Connecticut, United States. Founded in 1701, Yale is the third-oldest institution of higher education in the United States, and one of the nine colonial colleges ch ...
. Distributors such as Nostalgic Warehouse carry a wide range of decorative trim and accessories to dress up the appearance of a lock installation. Also, many European manufacturers whose products had previously been restricted to "designer" installations have recently gained wider acceptance and use. Some cabinet locks have also been fitted as mortise locks, though they are uncommon.


Notes


References


Further reading

*Peter Brett. ''Carpentry and Joinery'' Nelson Thornes, 2004.


External links


Lockwiki main page
{{Locksmithing Locks (security device) Door furniture