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Amortise lock (also spelledmortice lock inBritish English) is alock that requires a pocket—themortise—to be cut into the edge of thedoor or piece offurniture 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 olderbuildings constructed before the advent ofbored cylindrical locks, but they have recently become more common in commercial and upmarket residential construction in the United States.[citation needed] The design is widely used in properties of all ages in Europe.
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.[citation needed]
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 orrim 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.[1]
An early example of the use of mortise locks in conjunction with rim locks within one house exists atThomas Jefferson'sMonticello. In 1805, Jefferson wrote to hisjoiner 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 alsoescutcheon 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.[2] Jefferson ordered his locks from Paris. Similarly, mortise locks were used in primary rooms in 1819 atDecatur House in Washington, DC while rim locks were used in closets and other secondary spaces.[3]
The mortise locks used at Monticello werewarded locks.[2] 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.[4]
Warded locks were used in Europe from the Roman period onwards. Two English locksmiths,Robert Barron andJeremiah Chubb, played a major role in creating modernlever tumbler locks. 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.[5]
The next major innovation to mortise lock mechanisms came in 1865.Linus Yale, Jr.'spin 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.[5]
Mortise locks may include a non-locking latch operated by a door handle. An upright two-bolt lock is termed asash 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 adead lock. Dead locks are commonly used as a secure backup to a sprung non-deadlocking latch, now often a pin tumbler rim latch.[note 1][according to whom?] 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, uselever 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 theEuro 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 thelock body (the part installedinside the mortise cut-out in the door); thelock trim (which may be selected from any number of designs ofdoorknobs,levers, handle sets and pulls); astrike plate (orbox keep), which lines and reinforces the cavity in the door jamb or frame into which the bolt fits; and thekeyed cylinder which operates the locking/unlocking function of the lock body.
The installation of a mortise lock can be undertaken by an average homeowner with a working knowledge of basicwoodworking tools and methods. Many installation specialists such as carpenters use a dedicatedmortising 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 actuallyweakens the structure of the typical timber door, the embedded lock is typically stronger and more versatile than the newerbored 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 heavierreturn spring 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 theUnited States include Accurate, Arrow,Baldwin, Best, Corbin Russwin,Emtek Products, Inc, Falcon, Penn,Schlage,Sargent, andYale. 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.
| Fundamental concepts | |
|---|---|
| Lock hardware | |
| Keys | |
| Mechanical locks | |
| Electronic locks | |
| Other lock types | |
| Lock picking | |
| Door hardware | |
| Emergency access/exit | |
| Security alarms |
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| Miscellaneous | |
