A door lock works by using a cylinder mechanism that engages pins to prevent the door from opening unless the correct key is inserted. Let's break down the process:
Cylinder and Pins
The core of a door lock is the cylinder (also known as the lock body). This is the part where you insert your key. Inside the cylinder are a series of spring-loaded pins, typically arranged in a row. When the lock is in its locked state, these pins are positioned in a way that obstructs the cylinder's ability to turn. Specifically, the pins are split, and the break between the two parts of each pin is not aligned with the shear line (the point where the cylinder needs to rotate).
The Role of the Key
The key has a unique, uneven edge (the "bitting"). When you insert the correct key into the cylinder, the key's bitting pushes each of the spring-loaded pins upwards. The depth of each cut on the key corresponds to the height needed to lift the specific pin.
Unlocking Mechanism
When the correct key is fully inserted, the split in each pin aligns perfectly with the shear line of the cylinder. This allows the cylinder to rotate freely. Turning the cylinder activates the bolt or latch mechanism, which then retracts, unlocking the door.
Locking the Door
When you remove the key, the springs push the pins back down into their original positions, causing the breaks in the pins to misalign with the shear line again. This prevents the cylinder from turning, and the door remains locked. Many locks require you to turn the cylinder back in the opposite direction using the key to engage the bolt or latch fully, securing the door.
In summary, a door lock works by using a keyed cylinder with spring-loaded pins that align with the shear line when the correct key is inserted, allowing the cylinder to turn and unlock the door.
