The term "lockset" commonly refers to the assembly of door hardware that is used to hold a door in a closed position (Fig. 1). However, some holding hardware would more accurately be described by the term "latchset." A latch is a device that fastens a door in the closed position, is usually operable from both sides, and is constructed without a "deadbolt" or key-operated lock bolt. (A deadbolt differs from a lock bolt in that it is not beveled or spring loaded.) When a bolt is incorporated into a latch, the unit is known as a lock. A lockset includes not only the operable parts of the assembly but also the knobs, levers, handles, escutcheon plates, and other accessories that are typically included with them. The doorknobs, levers, pull handles, and push plates are also known as the operating trim. Locks may be of four types: cylinder, unit, integral, and mortised.
1.
Cylinder Locks
Cylinder locks are those types of locks that operate with a key-in-the-knob. The assembly is installed through holes bored in the door face and edge. Where a lock is not needed, this type of unit can be provided with a latch only. Cylinder locks are both relatively inexpensive and simple to install.
2.
Unit Locks
Unit locks are factory assembled as a single unit; all of their parts are contained within a metal frame. These locks are installed in a notch that must be cut in the edge of the door.
3.
Integral Locks
Integral locks are preassembled locks and incorporate both the security of mortise locks and the economy of cylinder locks. They are installed in a mortise (a recess cut into a door stile to receive the lock).
4.
Mortised Locks
Mortised lock assemblies are fitted into a mortised recess in the door. All of the parts are contained in a concealed unit, which has holes to receive the spindle of the operating knob or lever.
