How a Pin Tumbler Lock Works

How do key locks work?

    For every lock (F.1), there is a unique key. For the lock to work, only that key can fit. The reason for this is the ridges on the key. In each lock, there is a cylinder-like object that protects the main part of the lock, called a case(F.3). The metal circle that we put our key in is known as the plug(F.4). The plug only turns when the correct fitting key is put in. The opening  that we put the key into is called the keyway. In the inside of the case, there is the main mechanism that allows a key lock to work. There are multiple hollowed out shafts. Each shaft has a spring, and two pins. The pins are tiny cylindrical objects that smoothly slide through the shafts. There are two pins; the driver pin and the key pin(F.5)

. The spring is arranged touching the top of the shaft, with the driver pin under it and the kay pin under the driver pin. When a key is inserted, the ridges push the key pin up, contracting the spring. When the contacting part of the key pin and the driver pin align with the edge of the plug, the plug is able to turn. When the key pin does not align, the pin will block the plug from turning. Imagine you are in a building. There is a key for each lock, but there is also a master key. For this, the lock can have one or more extra pins inside, known as master pins, placed in between key pins and the driver pin. The master key pushed up so the edge of the driver pin and the master pin align with the edge of the plug. This way, both the normal key and the master key can be used to open the lock. Thank you for reading.

- Karthik Surapaneni

 F.1

 F.2

 F.3

 F.4

 F.5