# The Ultimate Combination Locks Quiz

Staff

Image: refer to hsw

Combination locks -- the keyless lock on your gym locker or the more complex ones found on safes -- are a very effective way of securing your belongings without the risk of losing a key. You turn the dial this way and that way, and eventually the lock opens. Wouldn't you like to know what's happening inside the lock? Take this quiz to learn more about how combination locks work.

# The wheel pack design used in modern combination locks has been around for how long?

The modern combination lock is based on a wheel pack mechanism that has been around for about 100 years.

# The combination dial is which part of the lock mechanism?

The combination dial is the numbered wheel that you turn to input the numbers of the combination.

# Which of these statements best defines a wheel pack?

A wheel pack is the collection of gears inside a combination lock. These gears are set to a particular combination, and work together to allow a combination lock to open.

# The combination dial is attached to which of these?

The spindle is a thin metal tube that extends from the dial, through the center of each gear in the wheel pack. When you turn the dial, the spindle rotates, and with it any gears that have been activated.

# What determines how many wheels there will be in a wheel pack?

Each time you change directions to input a number into the lock, you activate a different wheel in the pack. There will be as many wheels as there are numbers in the combination.

# The tab that extends outward from a gear wheel is called what?

Each gear wheel, or cam, will have a tab known as a drive pin, which extends outward toward the face of the combination dial.

# As a gear turns, its drive pin is caught by another small tab known as what?

As a gear turns, its drive pin will eventually latch onto a similar tab known as a wheel fly, which extends backward from the adjacent gear. When the drive pin latches unto the wheel fly, the adjacent gear joins the other rotating gears.

# Each wheel has a small gap in its perimeter known as what?

Along the perimeter of each wheel is a small notch, appropriately called a wheel notch. When the correct combination has been entered, the notches line up to create a gap.

# Which of these is likely to have a locking mechanism with a fence?

Large combination locks, like those you might find in a safe, have a component known as a fence. The fence keeps the mechanism locked by blocking the safe's bolt.

# What happens to a combination lock's fence once the wheel notches line up?

When a combination has been correctly entered, the fence will fall under it's own weight into the slot created by the lined-up wheel notches.