Locksmith Lock Mechanisms 3 — Questions and Answers
Question 1: In a lever tumbler lock, what must happen for the bolt to retract?
- All levers must be lifted to the exact correct height to align their gates with the bolt stump (Correct answer)
- The levers must all fall to their lowest position
- Spring pressure must be relieved from the driver pins
- The cam must disengage from the follower
Correct answer: All levers must be lifted to the exact correct height to align their gates with the bolt stump
Each lever tumbler must be lifted by the key to precisely align its gate (slot) with the bolt stump, allowing the bolt to slide and retract.
Question 2: Which lock mechanism is most commonly found in high-security padlocks used for commercial applications in the US?
- Warded mechanism
- Wafer tumbler mechanism
- Pin tumbler mechanism with hardened steel inserts (Correct answer)
- Simple cam mechanism
Correct answer: Pin tumbler mechanism with hardened steel inserts
High-security commercial padlocks typically use pin tumbler mechanisms combined with hardened steel inserts and anti-drill plates to resist physical attacks.
Question 3: What is a 'spool pin' designed to do in a high-security lock?
- Replace the standard cylindrical driver pin to resist picking by creating a false set (Correct answer)
- Increase the spring tension on each pin stack
- Prevent the key from being withdrawn once inserted
- Lubricate adjacent pin stacks automatically
Correct answer: Replace the standard cylindrical driver pin to resist picking by creating a false set
Spool pins have a narrow center section; during picking, they catch at the shear line and cause the plug to partially rotate to a false set, signaling the picker that further work is needed.
Question 4: A rim cylinder lock is typically mounted:
- Inside a mortise cutout in the door edge
- On the surface of the door with a connecting bar to a rim lock case on the interior (Correct answer)
- Within the door knob assembly
- Recessed into the door frame strike
Correct answer: On the surface of the door with a connecting bar to a rim lock case on the interior
Rim cylinders mount through the door face from the outside and connect via a tailpiece or connecting bar to a rim lock case attached to the interior door surface.
Question 5: What does the term 'key bitting' refer to?
- The process of cutting warding grooves into a blank
- The specific cuts made on a key blade that determine which locks it will operate (Correct answer)
- The angle at which the key enters the keyway
- The number of pins a key must lift
Correct answer: The specific cuts made on a key blade that determine which locks it will operate
Key bitting refers to the pattern and depth of cuts along the key blade that correspond to the height of each pin stack in the lock.
Question 6: In a tubular (ace) lock, how does the key differ from a standard pin tumbler key?
- It is thicker and made of hardened steel
- It has a hollow cylindrical shape with cuts arranged radially around its circumference (Correct answer)
- It operates levers instead of pins
- It uses magnetic coding rather than mechanical cuts
Correct answer: It has a hollow cylindrical shape with cuts arranged radially around its circumference
Tubular lock keys are cylindrical and hollow, with bitting cuts arranged in a circle around the key tip that correspond to pins arranged radially in the lock.
Question 7: What is the 'bible' in a pin tumbler lock?
- The manufacturer's pinning chart for that lock model
- The portion of the lock shell that houses the pin stacks and springs above the plug (Correct answer)
- The keyway profile diagram
- The legend printed on the lock's packaging
Correct answer: The portion of the lock shell that houses the pin stacks and springs above the plug
The 'bible' is the upper portion of the lock shell (housing) that contains the pin chambers, driver pins, and springs directly above the plug.
Locksmith Lock Mechanisms 3
In a lever tumbler lock, what must happen for the bolt to retract?