Master pin is a specialised component in lock tumbler mechanisms, pivotal in both the design and functionality of master key systems. It consists of a small pin, positioned within the lock cylinder, that allows different keys to operate the same lock. This pin acts as an intermediary between the driver pin and the key pin, creating an additional shear line which enables more than one unique key to operate the lock by aligning with these lines at different heights.
In master key systems, master pins are integral for hierarchical access control, often used in commercial and residential buildings to provide varied levels of security. The inclusion of these pins enables locks to be opened by both individual keys and master keys, which can open multiple locks within the same system. The precise arrangement and size of master pins dictate the complexity and security level of the master key system. The engineering of these systems requires meticulous planning of pin placement and key cuts to ensure security while providing convenience and system-wide access as needed. The use of master pins thus reflects a balance between accessibility and security in keyed lock systems.