How a Pin-Tumbler Lock Opens

In the picture

1. 1Housing: the fixed outer body that holds the pin chambers.
2. 2Plug: the rotating cylinder that the key enters and turns.
3. 3Pin stack: a lower pin and an upper pin that meet inside a chamber.
4. 4Spring: the coil that pushes the pin stack down when the key is removed.
5. 5Key: the toothed blade whose cuts lift each pin stack to the plug edge.

Examples

• A house key opening the front door.
• A bike lock key releasing the lock.

Quiz: How a Pin-Tumbler Lock Opens (Age 12)

1. 1

   According to the card, what must the right key do so the plug can rotate?

   • Push all pin stacks down with the spring.
   • Line up only the tallest pin stack.
   • Line up every pin pair.
2. 2

   What happens when someone tries to open the lock with the wrong key?

   • All pin pairs line up at the plug edge.
   • At least one pin stack is left in the way.
   • The spring turns the plug by itself.
3. 3

   Which part is the rotating cylinder that the key enters and turns?

   • Spring
   • Housing
   • Plug

The answers, each with its explanation, are in the app. This quiz is free there while the lesson is in the free week.