Pin Tumbler & Cylinder Mechanisms Flashcards
7 cards from real CPL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pin Tumbler & Cylinder Mechanisms flashcards as text
What is 'top of stack' in the context of a pin tumbler cylinder?
Answer: The driver pin (or spring) positioned at the top of each pin chamber in the shell
The top of the pin stack refers to the driver pin (and spring above it) sitting in the shell chamber above each key pin.
Which condition describes 'overset' pins during single-pin picking?
Answer: A pin stack set too high, with the driver pin above the shear line and the key pin crossing it, blocking rotation
An overset pin occurs when too much upward force pushes a key pin across the shear line, causing it to block the plug instead of the driver pin.
What is the primary advantage of a rotating-element (RE) security pin in a pin tumbler cylinder?
Answer: It rotates freely, resisting the tactile feedback a picker uses to detect binding
Rotating (RE) security pins spin under picking pressure, eliminating the tactile feedback that pickers rely on to detect the binding pin.
A locksmith is impressioning a lock. What does a 'mark' on the key blank indicate?
Answer: A spot where a pin tumbler has bound against the blank, showing where a cut is needed
During impressioning, binding pin tumblers leave a bright scratch or mark on the key blank at the exact positions where cuts must be filed.
What does the term 'key section' (or 'key blade profile') refer to?
Answer: The cross-sectional shape of the key blade that must match the keyway
Key section refers to the cross-sectional profile of the key blade, which must match the specific keyway shape to enter the cylinder.
When a cylinder has 'tight pin chambers,' what problem can arise during operation?
Answer: Pins may stick and not return to their rest position, causing intermittent lock failure
Tight or corroded chambers can cause pins to bind and not drop freely, leading to intermittent failures where the key may not turn consistently.
In a double-cylinder (double-keyed) deadbolt, what is different compared to a single-cylinder deadbolt?
Answer: Both interior and exterior sides require a key to operate; there is no thumb turn
A double-cylinder deadbolt has pin tumbler cylinders on both sides of the door, requiring a key to lock or unlock from either side with no thumb turn.