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Different Parts of a Door Lock and When to Replace Them

Fact checked by Teddy B.Miller

parts of a door lock

Why do we need to know about parts of a door lock? The thing is, when our door lock no longer works as intended, we tend to replace the whole thing right away. But, the problem might occur to a small part of the lock, so purchasing a whole new one might be a waste.

Besides, various lock types on the market make it challenging to choose one for residents or offices. So, if we are familiar with basic locksmithing terminology, we can distinguish different locks to decide the suitable one we need.


What Locks Do We Often Use?


Most commercial and residential properties use traditional locks (also called mechanical locks) to protect their interior. Perhaps it is the first type of lock that comes to your mind when thinking about door locks operating with a key, handle, or knob.

This article will show the main parts of a traditional door lock, both external and internal elements, along with signs you need to replace them. You might want to search for the door lock parts names diagram in case you need better visualization.

Parts of a Cylinder Lock & Signs for Replacement


We will discuss different components of a door lock. It is better for you also to learn the replacement signs of some crucial door parts, such as the cylinder or strike plate.

1. Cylinder


A lock cylinder consists of the whole locking mechanism. Inside the lock, it plays the main role, so most people refer to it as the lock body.

This unit is loaded with a spring and several pins. They do not turn by chance, only when you push them in the correct direction and pattern them by the compatible key. As a key enters a keyhole, it goes into the cylinder; then, the key ridges make contact with these spring-loaded pins.

After the pins are correctly aligned, the cylinder opens to allow the bolt movement and unlocks the door. Cylinder locks are widely used for exterior door locks, thanks to their considerable security.

Signs for replacement:

  • Difficulty or sticking key rotation inside the lock
  • A broken key inside the cylinder.

2. Bolts

Small but important parts of a lock, bolts will protrude from your door to make a door frame engagement when the cylinder is locked, then recede when unlocked. This part stops or permits the opening of a door.

Since there are multiple bolt types for door lock use, you should take a look at the most common ones below:

1, Spring Bolt/Latch Bolt


A spring bolt/latch bolt functions with a spring clip holding it in place. When the door is unlocked, it compresses the spring; thereby, the bolt moves into the lock body and allows your door to open.

When this spring is released, it reverts the bolt to the natural locked position. This means shutting the door will result in the automatic self-lock of the spring bolt without the need for a key.

It allows us to leave the house knowing it locks securely behind us.

Yet, keep in mind that this type of lock can easily lock you out of the house while your key is still inside. This mostly happens when you go out to throw out the garbage or collect mail. Just seconds later, the door has been slammed shut by a breeze, along with a spring bolt that locks you outside.

That explains why these lock owners usually have extra keys outside the house to help access their property if such situations occur.

2, Deadbolt


A deadbolt does not function with a spring system. You can only lock or unlock it using a key from either of the door sides. Most people agree that deadbolts offer more security than spring bolts since you cannot force them back into your lock without the compatible key.

3, Barrel Bolt


A barrel bolt contains a long, horizontal metal cylinder guided by a push of thumb for the locking or unlocking of your door. The barrel bolt engages with the door frame’s matching metal cavity when you lock it and withdraws inside the faceplate when opened.

You will often find such bolts on internal doors, for example, the bathroom. On the other hand, they are not the best choice for external ones because they fall apart easily if your door is kicked down. But some homeowners add these bolts to external doors on top of a spring bolt or deadbolt to enhance security.

4, Hinge Bolt


Hinge bolts are fitted on the door side to add extra security. When someone is attempting to break-in, the bolt mechanism prevents your double doors from being forced off the hinges.

This lock type is suitable for any doors made out of wood with a hardened steel bolt. It will protrude from your door frame, then locks into a hole when you close the entire door.

3. Strike Plate


The strike plate is a metal piece fixed to your door frame at the equal level of the lock. Its opening hole engages with the bolt whenever you lock the door. In some cases, a strike plate has a lip for the correct direction guide of the bolt.

Signs for replacement:

  • Either wrapped, cracked, or bent
  • Stripped screws

4. Keyway


This is one of the important parts of a door lock mechanism, as it allows inserting the key and pushing through to get to the lock cylinder.

5. Rotor


A rotor is engineered in the lock cylinder and turns when you insert the correct key for bolt release.

6. Cotter Pin

After you enter the compatible key into your door lock, the rotor turns, thanks to the cotter pin. This metal piece undergoes pressure from its spring and aligns with the key grooves, forming the correct pattern to release the bolt.

7. Spring


The spring is basically a coiled piece made from flexible metal to add pressure to the cotter pin. It prevents the pin from moving the rotor unless you adjust a specific pin set to align correctly.

8. Stator

You might never hear of small parts of a door lock called the stator, an additional component to the cylinder lock, and it makes an interaction with the rotor. It enables the rotor to turn as a key aligns with correct grooves.

9. Trim

This is another metal plate that houses the keyway and protrudes from your door. Normally, its position is below the door handle or knob. Not all locks have the trim, but you will usually find its presence on a cylinder lock.

People also call the trim a ‘rose’ or have other names for particular shapes, such as a circular trim known as a ‘ring’. Various types of trim are available to go well with your house style.

10. Face Plate


The face plate is fixed to the outside of the door’s vertical edge. Its internal hole for the bolt to pass and lock inside the door frame’s corresponding strike plate.

11. Spindle

A spindle is responsible for connecting the door knobs or handles on two sides. This rod shape is square because it releases the door latch to open it as soon as you turn the knob or push the handle down.

12. Knob Or Handle


A door handle/knob are the same door locks parts names. There will be an exterior handle/knob and an interior side on each cylinder door lock. You can fit them separately to your lock, or they are fixed parts on a lock frame.

You either twist the knob left or right to unlock a door, while you push a door handle downwards. In reality, a handle provides more grip than a knob. That is why the door handle is ideal for people with limited strength in their hands to operate the door.


After reading this article introducing these components, we hope that you have acknowledged a lot about various door locks parts. It will be far easier to fix or replace small units rather than spending money to get a brand new cylinder door lock just because of minor issues.

Care to let us know your opinion on the article? Feel free to drop a comment right below. Also, do not forget to share this with friends and family via social media to learn about this. It is never too late to know all the components of a cylinder door lock.

Thank you for reading.

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