Mortice is a lock that requires a pocket—the mortice—to be cut into the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortice 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. They are widely used on all ages of domestic properties in Europe.
Mortice locks may include a non-locking sprung latch operated by a door handle. These are termed ‘sash locks’. A simpler form without a handle or latch is termed a ‘dead lock’. Dead locks are commonly used as a secure backup to a sprung non-deadlocking latch, usually a pin tumbler rim lock.
Mortice locks have historically, and still commonly do, use lever locks as a mechanism. Older locks may have used warded locks. This has led to a popular confusion between the two; the term ‘mortice lock’ is widely known and used, but usually in reference to lever keys. In recent years the Euro cylinder lock has become common, using a pin tumbler lock in a mortice housing.
The parts included in the typical mortice lock installation are the lock body (the part installed inside the mortice cut-out in the door); the lock trim (which may be selected from any number of designs of doorknobs, levers, handle sets and pulls); a strike plate, or a box keep, which lines the hole in the frame into which the bolt fits; and the keyed cylinder which operates the locking/unlocking function of the lock body. However, in the United Kingdom, and most other countries, mortice locks on dwellings do not use cylinders, but have lever mechanisms.
It cannot generally be undertaken by the average homeowner since it is labor intensive and requires a working knowledge of basic woodworking tools and methods. Many installation specialists use a 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 mortice lock actually weakens structure of the typical timber door, it is stronger and more versatile than a bored cylindrical lock, both in external trim, and functionality. Whereas the latter mechanism lacks the architecture required for ornate and solid-cast knobs and levers, the mortice lock can accommodate a heavier return spring and a more solid internal mechanism, making its use possible. Furthermore, a mortice lock typically accepts a wide range of other manufacturers’ cylinders and accessories, allowing architectural conformity with lock hardware already on site.
The purpose of a mortice lock is to act as a combination of locks. It is dual action meaning that it acts as a door knob and a deadbolt.
source: Wikipedia
