Pin Tumbler & Cylinder Mechanisms Flashcards

What is the purpose of the 'shear line' in a pin tumbler lock?

Answer: It is the gap between the plug and shell where pins must align to allow rotation

The shear line is the interface between the plug and the shell; when all pin stacks align at this line, the plug can rotate freely.

Which component in a pin tumbler cylinder directly contacts the key cuts?

Answer: Key pins (bottom pins)

Key pins, also called bottom pins, rest directly on the key blade and are lifted by the key cuts to different heights.

A locksmith discovers a cylinder where the plug spins freely without a key. What is the most likely cause?

Answer: All springs are broken or missing

If all springs are broken or absent, driver pins cannot drop back to block the shear line, allowing the plug to spin without a key.

What does 'master wafer' or 'master pin' refer to in a masterkeyed cylinder?

Answer: A small spacer pin inserted between key and driver pins to create an additional shear line

Master pins (also called master wafers) are short pins added between the key pin and driver pin, creating a second shear line that allows a master key to operate the lock.

In a standard 6-pin tumbler cylinder, how many pin chambers are present in the plug?

Answer: 6

A 6-pin cylinder has six chambers in the plug, each holding one key pin aligned with the corresponding key cut.

What is 'bible' in the context of a pin tumbler cylinder?

Answer: The upper housing of the cylinder shell that contains the driver pins and springs

The bible (or shell body) is the upper portion of the cylinder housing that retains the driver pins and springs above the plug.

Which action during lock picking exploits manufacturing tolerances in a pin tumbler cylinder?

Answer: Applying rotational tension to bind pins one at a time at the shear line

Single-pin picking applies tension so that manufacturing tolerances cause one pin to bind at the shear line at a time, allowing the picker to set each pin individually.