North Carolina Locksmith Practice Exam

Which part of the cylinder surrounds the plug and contains tumbler chambers?

1. Shell

2. Strike

3. Spring Latch

4. Trim

The correct answer is: Shell

The shell of a lock cylinder is the outer casing that provides structural support and protection for the inner mechanisms, including the plug and tumbler chambers. This component encloses the plug, which is the part of the cylinder that can be rotated with the correct key, allowing for the locking and unlocking of the mechanism. The tumbler chambers, where the pins or tumblers reside, are integral to the locking system's functionality, as they interact with the plug to either allow or prevent rotation based on whether the correct key is inserted. The strike refers to the plate installed on a door frame that serves as a receiving point for the latch or bolt but does not encompass the locking mechanisms. A spring latch typically refers to a type of latch mechanism that uses a spring to operate, not related to the cylinder structure itself. Lastly, trim is the decorative or functional exterior part of the lock that often houses the door handle or knob, providing access but not encompassing the internal workings like the shell does. Understanding the role of the shell helps locksmiths and those in training appreciate how each component contributes to the overall function and security of a lock.