15 Parts of a Door Lock – With Diagrams For Cylinder Lock & Padlock

The security of one’s house should be everyone’s number one priority, and choosing a lock for your door is usually difficult, which is why everyone needs to acquaint themselves with the different parts of a door lock because doing so will make it a lot easier to understand the differences and pros and cons of different types of locks.

The most commonly seen lock is the mechanical lock, used in both residential and commercial settings. They are the most basic type of locks – with a keyhole and a doorknob/handle.

What Are The Parts of a Door Lock ?

The Cylinder

The cylinder is the main part of the lock. It is laid with pins that are unique to every set of lock and keys, and will only be pushed into alignment when the correct key with properly corresponding ridges has been inserted, which will then allow the cylinder to spin, moving the bolt and thus unlocking the door.

The Bolts

Parts of a door lock

Bolts are what keeps a locked door from opening by latching into the doorframe. It is the part of the lock that protrudes from the side of the door when the door is locked. There are many different types of bolts, the most common of which are mentioned herein:

The Spring Bolt

Parts of a door lock

Spring bolts are made so that they are always locked, and when unlocked and left alone, the bolt springs back into its initial position of being locked. This means that the door locks automatically, without the need for a key.

If you forget to lock your door, or you can’t get the time to regularly, this is a great option, however, it is common for people with spring bolt locks to accidentally lock themselves out of the house with the key still inside, which is why people with these kinds of bolts usually keep a spare key hidden somewhere outside the property, for this kind of situation.

The Deadbolt

Deadbolts can only be locked or unlocked with the key, regardless if you’re inside or outside. They are usually considered safer, due to their mechanism not allowing the bolt to be forced back in without the correct key, something which can potentially happen with spring locks.

The Barrel Bolt

Barrel bolts are only useful for the inside of the door, as they use no key and are engaged or disengaged by hand. They consist of a horizontal cylinder that is pushed into place to latch the door onto the back or front of the doorframe. They are mostly used for toilets or bathrooms, or as locks for extra security for the inside of the front door.

The Hinge Bolt

Hinge bolts are an additional piece of security that can be very useful. They are mounted on the opposite side of the door of the main lock and help prevent the door from being taken off its hinges.

The Hook Bolt

Hook bolts are used for sliding doors, and they consist of a spring bolt that is attached to a hooked latch.

The Strike Plate

The strike plate is a metal plate, mounted on the door frame right next to the lock, with a hole for the bolt to pass through as it enters the frame. This ensures that the doorframe remains strong and doesn’t wear out or break over time.

The Keyway

A keyway, or keyhole, is where the key is inserted before it enters the cylinder.

The Rotor

The rotor is what moves the bolt once the correct key is inserted into the cylinder.

The Cotter Pin

The cotter pin is what allows the rotor to spin when the correct key is present. When put under pressure of the correct key, it releases the rotor and allows it to release the door.

The Spring

The spring is placed under the cotter pin, to prevent it from moving until all the pins from the cylinder are matched properly.

The Trim

This is the metal plate that sticks out of the door, and it is usually located under the doorknob. Not all locks have a trim.

The Face Plate

The face plate is mounted on the side of the door so that it sits in between the door and the frame when the door is closed. It has a hole, through which the bolt passes and locks into the doorframe.

The Spindle

The spindle is a four-cornered rod that connects both doorknobs to a latch, which in turn allows or stops the door from opening when the handle is in a certain position.

The Handle or Knob

The knob or handle is turned or pushed down, which then allows the door to open. Handles are usually considered better options, because of the better grip they provide.


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