HOW STUFF WORKS
QUIZZES

The Ultimate Master Key Quiz
by Staff
Did you ever think why your door key opens only your lock, and each of your neighbors' keys opens only each of theirs -- but the superintendent can open everyone's locks? How many keys does he carry anyway? The key to this question is in this quiz.

### If a large apartment building has a hundred apartments, how many keys does the superintendent need to open the doors?

• none because the owners have their own keys
• one
• 100

### What is the most common lock design?

• tumbler lock
• pin lock
• cylinder lock

### What happens when you turn the cylinder in a cylinder lock?

• It turns a cam.
• It turns a plug.
• It turns a spring.

### Using the correct key to open a cylinder lock is comparable to:

• stringing together a string of beads
• conducting a wrestling match
• solving a puzzle

### What are the main components of a pin and tumbler lock?

• small metal pins
• tiny, metal, tumbler-looking receptacles
• neither of the above

### How are the pins grouped together?

• they're not grouped; they fit singly in the unit
• in threes
• in pairs

### What keeps the plug from turning?

• the position of the bottom pins
• the position of the upper pins
• the housing unit

### What is meant by the term, the shear line?

• You insert a key into a lock and the key is aligned with the two sides of the lock.
• The right key is put into the lock and the pins line up perfectly.
• A master key that can open any door &quot;shears&quot; against the pins.

### In locks of a specific group that can be opened by a master, some pin pairs are separated by a third pin. What is this third pin called?

• master wafer
• spacer
• both of the above

• a gap
• a spacer
• a notch
more stuff
more stuff