Pin Tumbler & Cylinder Mechanisms Flashcards

What is 'plug retention' in a pin tumbler cylinder, and which component typically provides it?

Answer: Keeping the plug inside the shell; typically provided by a retaining clip, C-clip, or tailpiece assembly

Plug retention keeps the plug from sliding out of the shell and is usually achieved with a retaining clip, C-clip, or cam/tailpiece that captures the plug in the housing.

The 'bitting list' for a key system is used to:

Answer: Document all valid key cut combinations within a key system to manage key codes and avoid duplication

A bitting list is a master record of all assigned key combinations in a key system, helping the locksmith manage codes and prevent issuing duplicate keys.

Which type of spring is most commonly used in modern pin tumbler cylinders?

Answer: Coil (helical) spring

Coil (helical) springs are the standard in pin tumbler cylinders because they fit compactly above the driver pins in the pin chambers.

What does 'cross-keying' mean in a masterkey system, and why is it problematic?

Answer: A condition where a change key operates a lock it should not, due to master pin combinations creating unintended shear lines

Cross-keying (or phantom keys) occurs when the combination of master pins creates an accidental shear line that allows an unauthorized change key to open another change-key lock in the system.

What is the purpose of warding in a pin tumbler cylinder's keyway?

Answer: To physically block incorrect or unauthorized key blanks from entering or fully inserting into the keyway

Warding consists of projections inside the keyway that allow only keys with matching cuts or clearances to insert, providing a first level of key differentiation.

A locksmith is asked to 'rekey to a factory original' on a residential lock. This means:

Answer: Set the pin tumblers to match the original factory key bitting using the manufacturer's key code

Rekeying to factory original means pinning the cylinder to match the original key bitting as specified by the manufacturer's code records.

Which statement best describes the difference between a 'change key' and a 'master key' in a pin tumbler master key system?

Answer: A change key opens one specific lock in the system; a master key opens multiple or all locks in the system

A change key (or sub-master key) operates a single lock or specific group, while a master key is designed to operate all locks within its level of the key system.