CML Lock Mechanisms & Hardware 2 — Questions and Answers
Question 1: What is the primary function of a cam in a pin tumbler lock cylinder?
- To tension the plug during picking
- To actuate the locking bolt or latch when the plug rotates (Correct answer)
- To align the driver pins with the shear line
- To prevent key extraction when under tension
Correct answer: To actuate the locking bolt or latch when the plug rotates
The cam is attached to the rear of the plug and directly actuates the locking mechanism (bolt or latch) as the plug rotates.
Question 2: In a high-security lock, what is the purpose of a sidebar?
- To increase the number of bitting positions
- To provide an additional locking mechanism that must align before the plug can rotate (Correct answer)
- To protect against drill attacks on the plug face
- To allow the lock to be masterkeyed more easily
Correct answer: To provide an additional locking mechanism that must align before the plug can rotate
A sidebar is a secondary blocking mechanism that requires its own set of cuts or rotations to align before the plug is free to turn, defeating common picking techniques.
Question 3: What differentiates a 'dead latch' from a standard spring latch?
- A dead latch uses a mortise cylinder instead of a rim cylinder
- A dead latch has a plunger that deadlocks the latch bolt to prevent it from being pushed back (Correct answer)
- A dead latch is always operated by a key from both sides
- A dead latch bolt is tapered on both sides instead of one
Correct answer: A dead latch has a plunger that deadlocks the latch bolt to prevent it from being pushed back
A dead latch has a small auxiliary plunger that, when depressed by the strike plate, prevents the latch bolt from being pushed back by a credit card or similar tool.
Question 4: Which warding type in a lock cylinder is designed specifically to prevent the insertion of incorrect keys?
- Sidebar warding
- Milling warding
- Paracentric warding (Correct answer)
- Profile warding
Correct answer: Paracentric warding
Paracentric warding features complex keyway profiles with curves extending past the center line, making it difficult to insert non-brand keys and increasing picking resistance.
Question 5: A locksmith is examining a Medeco lock. What is the unique feature that distinguishes Medeco's security over standard pin tumbler locks?
- It uses ball bearings instead of driver pins
- Its key cuts have angular bitting that rotates the pins to align a sidebar (Correct answer)
- It incorporates a secondary disc detainer system
- It uses a figure-eight keyway for restricted key control
Correct answer: Its key cuts have angular bitting that rotates the pins to align a sidebar
Medeco cylinders require key cuts to both lift pins to the shear line AND rotate them to specific angles so sidebar slots align, combining height and rotation for dual authentication.
Question 6: What is a 'false gate' in the context of combination lock design?
- A secondary dial used for emergency opening
- A shallow notch on a wheel that momentarily mimics the true gate to defeat manipulation (Correct answer)
- An incorrect combination entry that triggers a relocking device
- The gap between the dial face and the lock body
Correct answer: A shallow notch on a wheel that momentarily mimics the true gate to defeat manipulation
False gates are shallow notches machined into combination lock wheels that cause the fence to partially drop, creating misleading feedback to someone attempting to manipulate the lock.
Question 7: When installing a cylindrical lockset, what is the correct relationship between the latch backset and the edge bore?
- The edge bore must always be 1 inch larger in diameter than the backset measurement
- The edge bore center must be located at the same distance from the door edge as the specified backset (Correct answer)
- The backset is measured from the door hinge, not the edge
- The edge bore diameter determines the backset automatically
Correct answer: The edge bore center must be located at the same distance from the door edge as the specified backset
The backset is the distance from the door edge to the center of the cross bore, and the edge bore must be centered at that exact distance to ensure proper latch alignment with the strike.
CML Lock Mechanisms & Hardware 2
What is the primary function of a cam in a pin tumbler lock cylinder?