How do padlocks work?

What's inside these mechanical devices that give you peace of mind?

(Image credit: MasterTux/Pixabay)

Most of us leave the doors to our houses locked, feeling a sense of assurance that our cherished items are protected. But what about when you’re in public? How can you keep your valuables out of reach from strangers without having to keep them on your person? This is where padlocks come into play.

From the tiny padlocks keeping the pages of diaries private to bulky, reinforced locks keeping iron gates secure, they’re as popular today as they’ve ever been. This compact and intricate system is used to attach two items together, such as a door and a frame, two ends of a chain or a chain and a fixed frame.

These portable security devices have served us for longer than you may think. The first padlocks appeared in ancient Egypt, before becoming more advanced for various uses and widespread across the world. Some theories suggest that the ‘pad’ from the name means ‘gate’, and that early forms of padlocks were predominantly used to attach to gates – preventing trespassing.

This security is very important, as we often become emotionally attached to our belongings, even if it’s not something high in financial value. Whether we need to secure our bikes up outside or keep our clothes and valuables contained in a locker at the gym, padlocks ensure we don’t have to keep a constant eye on our possessions and keeps them safe from being stolen.

Padlock unlocked

How the unique pattern on a key causes the tumblers to turn within

(Illustration by The Art Agency/ Nick Sellers)

Cracking the code

Not all padlocks need keys. Combination padlocks often use a four-digit code to unlock. Inside these padlocks, four separate dials are connected to four cylindrical discs. With ten digits from zero to nine to choose from, only one of these numbers on each of the discs makes a gap within the cylinder line up in the correct place.

When the correct combination is set, a series of gaps allows the shackle to slide out with no obstacles. To re-lock the padlock, all the numbers need to be shuffled again, keeping the lock closed. While it would take a significant amount of time to break the code without knowledge of the correct combination, these padlocks are thought to be less secure than those using keys. However, keyless systems mean there is no possibility of losing a key and being locked out from your possessions. Taking the time to try out all possible combinations would look suspicious, but you would be able to get in eventually.


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