12 Key Door Knob/Lock Parts Guide: Names, Function & Diagram

The one question arising in our minds is why it’s important to know about the door knob parts or door lock parts. The answer is that when our door knob or lock is not working correctly, then we need to show it to the repair person. He might suggest replacing the entire door lock. If anyone knows about every part of a door knob, then he can replace only the damaged part. So it will save lots of money along with valuable time. This article gives you all information about door lock anatomy, components, names, and diagram.

Door Knob Parts Diagram

Door Knob/Lock Parts, Names, and Diagram

Door Knob Parts Names

  • Cylinder or Lock Body
  • Bolts
  • Strike Plate
  • Keyway
  • Rotor
  • Cotter Pin
  • Spring
  • Stator
  • Trim
  • Face Plate
  • Spindle
  • Door Knob or Handle

Parts of a Door Knob/Lock and Functions

Cylinder or Lock Body

The cylinder is the main part of the door lock where we insert the key. This cylinder is also called a lock body. The lock body consists of the total locking mechanism of the door lock.

It consists of a spring and several spring-loaded pins. To open the lock, we need to insert the correct key with the right pattern in the correct direction.

When we insert the right key in the keyhole, the uneven edge of the key pushes the pin to fit the height of the key in the lock body. All pins move at the correct place, which causes the cylinder to open and allows the bolt to move.

It causes the door to open. Cylinder locks are one of the common examples of exterior locking arrangements.

Bolt or Latch

The bolt or latch is the part of the door lock made up of metal. It extends from the door and engages with the door frame when the cylinder is in the locking position and disengages when the cylinder is in unlock position.

The function of bolts is to give permission to stop or permit opening the door. There are many types of latches used in a door locking mechanism.

Below are some common examples of bolts or latches.

Spring Bolt

The spring bolt or latch bolt is a spring clip used to hold the bolt in place. When the door is in the unlock position, the spring clip compresses.

It helps the bolt to move in the lock body, which causes the door to open. When the spring releases, the spring retains its original position as previously.

The spring bolt automatically locks itself without any key while shutting the door. This type of locking mechanism is very useful when we rush the leave the house and helpful for those who forget to lock the door every time.

The main drawback of this door lock is that there are chances of forgetting the key inside the house.


The deadbolt is one of the secure locking mechanisms because it does not use any spring. This deadbolt door lock gets open or closed by the correct key only.

Barrel Bolt

The long metal cylinder in the horizontal direction is used in the barrel bolt. This mechanism is guided using a thumb during locking or unlocking the door.

When we lock the door, the barrel bolt engages with the hole in the metal cavity, and when we unlock the door barrel bolt is drawn out from the faceplate.

These barrel bolts are used on the inside of the bathroom door. But this is not the ideal locking mechanism for an external lock because the door breaks when someone kicks the door hard.

Hinge Bolt

Hinge bolts are available on the sides of the door, and it provides additional security to the door lock. It helps to prevent the door from opening when someone tries to enter forcefully.

This hinge bolts mechanism is found on the wooden door, which uses a hardened steel bolt that extends from the door frame and it locks the door when this bolt goes to that hole.

Hook Bolt

These types of locking mechanisms are commonly found on sliding doors. They use a spring bolt on a pivot with a hook-shaped head.

Strike Plate

The strike plates are made up of metal attached to the door at the same height as the latch. The strike plates contain an opening into which the bolt engages when the door is in the locking position, whereas the bolt disengages when the door is in unlock position.

The lip guides the bolt in the correct direction in some strike plates. Strike plates are the parts of a door lock that are easy to replace when damaged.


Keyway is the slot or opening in a cylinder or lock body where we insert the key and rotate it in the right direction.


The rotor is placed inside the cylinder of the door lock. When we insert the correct key in the keyhole and rotate, the rotor gets turned to release the bolt.

Cotter Pin

The Cotter pin is the only reason to turn the rotor when we insert the correct key in the keyhole of the door lock. Its material is metal that undergoes pressure applied from the spring.

It is aligned in the grooves and forms the correct pattern, so the bolt gets moved.


The stator is the additional part of the door lock which interacts with the rotor and enables the rotor to turn when the key aligns in the correct grooves.

Trim or Rose

The trim is another part of metal that extends from the door and contains the keyway. It is not found in every type of door lock but is commonly found in the cylindrical lock. It is placed before the doorknob

Face Plate

It is a metal plate fixed to the external vertical edge of a door. It has a hole in it through which the bolt can pass and lock into the corresponding strike plate on the doorframe.


The spindle is a part of the door lock connects the door handle or knob on both sides of the door. A spindle is a square rod that releases a latch inside the door.

It allows the door to open when the doorknob rotates left/right, and the handle is pushed in a downward direction.

Door Knob or Door Handle

The doorknob or Door Handle is the basic part of door locks. The outside part of the door lock is called an exterior doorknob or handle, whereas the inside part o the door lock is called an interior doorknob or handle.

This interior or exterior doorknob or handle fits separately or comes with a locking frame. When the doorknob rotates toward the left or right, it opens the door, whereas the handle pushes downward to open the door.

The doorknob looks more attractive and improves the aesthetic of our door also.

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