Anatomy of a Residential Door Lock

Brass DoorknobThe typical residential door lock is a device used for securing a door in place, and allowing or denying access to what's behind the door. The lock is released by a physical object such as key, keycard, fingerprint or a combination of these things.

There are many parts of a door lock. Knowing how a residential door lock works and learning about its key components should give you some idea as to where the problem may lie if it doesn't function properly. Just keep in mind that some of the more sophisticated or expensive door locks can have additional components.

The Key Components of a Residential Door Lock

1. Knob – Residential doors often use knobs that use keyed entry, where there is a keyhole on the outside of the door, and there a hidden locking mechanism on the inside. It locks by turning or pressing a small button. For aesthetic purposes, the knob can take on different shapes including round balls, levers, triggers, etc., but they all work the same way.

2. Dead Latch – Also called the cylindrical dead latch, it is the component that retracts or engages with the key. It is the metal tongue-like protrusion that is located at the side of the door which makes the door knob join together through the latch. A dead latch may become broken, sticky, and ineffective. The use of a flexible latch may be the best way to achieve added security because standard latches can be easily forced open.

3. Strike Plate – Comes in many different designs, it is aligned with the dead latch and is attached to the door frame. This is where the dead latch goes through in order for the door to have a secure lock and a positive closure.

4. Rose Insert – A plate that is located in the middle of the door and the inside knob.

5. Cylinders – It is the most essential aspect of the door lock, the lock cylinder contains the key’s code and it will determine whether the door will lock or unlock. If you have the wrong key, the lock cylinder would not allow unlocking of the door.

6. Key – Not technically a part of the door lock, the key is used to lock and unlock the residential door from the outer side of the knob.

How a Residential Door Lock Works

To increase security in homes, residential doors have one of two types of door locking mechanisms. The door lock in your home may either be a deadbolt lock or a simple lock. The door knob may look simple, but it is a little bit more complex. There are a variety of pins and springs inside the cylinder that work with the key to lock and unlock the door.

The Pin and Tumbler mechanism means that there are a whole series of small pins that have different lengths and are placed in pairs having one on top of the other. Normally, door knobs have five pairs of pins that interact with a key that locks and unlocks the door.

When the correct key is inserted, the notches in the key will push the pins upward and allows the cylinder to move. It is designed to push all of the pins to the correct point where the cylinder can be free to rotate and unlock the door. Inserting a wrong key will not allow the cylinder to move in any way.

The locking mechanism of the cylinder also depends on the cam, the sole part that will rotate with the cylinder. The cam will release a spring to lock the door and should be reversed for it to unlock. Residential doorknobs also have lock buttons that will trigger the spring and will lock the door from the inside.

So those are the basics of a door lock. Your's probably works as described above. But like any device with moving parts, things sometime go wrong or wear out. This is when our Coral Springs locksmith service can help. If you're experiencing problems with the door locks in your home or business, give us call at 954-878-8878.