A Moment of Science

Under Lock And Key

Want to pick a lock? Align the pins, and doors will open up to you.

Correct key with cyclinder

Photo: harry harris (flickr)

A key's grooves raise each of the pins the correct length, allowing the cylinder to turn freely.

Have you ever tried to pick a lock but had no luck? Despite how easy detective and spy movies make it seem, picking a lock requires more than a paperclip and a simple turn of the wrist.

Do The Twist

When you put a key in the lock and twist, you turn what’s called the “cylinder,” which then turns a part of the lock called the “cam.” It is the cam that makes the bolt slide in or out of the door jamb.

Inside the lock are several shafts running through the cylinderand into the casing around the cylinder. Inside these shafts are pins of various lengths.

Without a key inside, the bottom half of each pin rests inside the cylinder, while the top of the pin extends beyond the cylinder to the surrounding casing, holding the cylinder in place. If you try to twist the cylinder without correctly moving the pins, the top pins will catch on the casing.

Breaking And Entering

This is where the correct key comes in.

When you insert the key, its notches raise the pins just enough so they are aligned with the space between cylinder and casing. Since all of the pins are even and clear the casing, the cylinder turns freely.

So the next time you find yourself locked out, just remember alignment is the key.

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