Yleisavainjärjestelmiä

Yleisavainjärjestelmiä, known in English as master key systems, are a type of lock security system that allows a single key, the master key, to open multiple different locks, while each lock can also be opened by its own unique key. This is achieved through a sophisticated arrangement of pin tumblers within the lock cylinders.

In a standard pin tumbler lock, a series of pins of varying lengths are positioned between the keyway and the shear line. When the correct key is inserted, the pins align at the shear line, allowing the cylinder to turn. In a master key system, an additional set of "master pins" is inserted between the regular pins. When the correct individual key is used, only the regular pins need to align at the shear line. However, when the master key is used, its specific cut allows it to align both the regular pins and the master pins at the shear line, thereby opening the lock.

These systems are commonly used in environments where access control needs to be managed efficiently, such as office buildings, hotels, and apartment complexes. They provide a balance between individual privacy and centralized control. For example, a building manager might have a master key to access all offices, while each office occupant has their own key to only their office. The design and implementation of master key systems require careful planning to ensure security and prevent unauthorized access. The complexity of the pinning can be extended to grand master key systems, where a grand master key can open all locks in a facility, and sub-master keys can open specific groups of locks.