Master Key Systems and Keying Flashcards

In a master key system, what is the 'change key' (also called 'servant key')?

Answer: The lowest level key that opens only one specific lock in the system

A change key (servant key) operates a single specific lock in the master key system, providing the most restricted level of access.

What is a 'master key' in a keying hierarchy?

Answer: A key that operates all locks in a specific group or the entire system, in addition to its own change key level

A master key operates all locks in its designated group by working in combination with the change key bitting through the use of master wafers (pins).

What are 'master wafers' (also called top master pins or master pins) in a pin tumbler master key system?

Answer: Additional small pins placed in chambers that allow the lock to be opened by both the change key and the master key

Master wafers are short pins added to a chamber, creating two shear lines — one for the change key and one for the master key — allowing both to operate the lock.

What is a 'grand master key' (GMK) in a master key hierarchy?

Answer: A key that operates all locks in the entire system, superseding all master keys and change keys

A grand master key sits at the top of a multi-level master key hierarchy and operates every lock in the entire system, across all groups and levels.

What is 'key control' in the context of a master key system?

Answer: The policies and hardware (restricted keyways, key tracking records) that prevent unauthorized key duplication and track key issuance

Key control encompasses the procedures, hardware, and documentation that prevent unauthorized key duplication and track who holds which keys in the system.

What is the 'maximum adjacent cut specification' (MACS) and why is it important in key cutting?

Answer: The maximum allowable difference in depth between adjacent cuts on a key, ensuring the key can be inserted without breaking the lock or key

MACS defines the maximum depth difference between any two adjacent cuts; exceeding MACS creates a key that cannot be smoothly inserted or withdrawn and may damage the lock.