Mortise Lock: A Guide to its Definition, Parts, Measurement and Operation
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Mortise Lock: A Guide to its Definition, Parts, Measurement and Operation

Views: 0     Author: Site Editor     Publish Time: 2023-04-14      Origin: Site

A mortise lock is a reliable and popular door lock that is commonly used in residential and commercial buildings. This locking mechanism provides a high level of security and long-lasting durability, making it an excellent choice for a wide range of applications. This article will help you better understand a mortise lock: what is, its parts, how to measure it and how does it work.

mortise lock set

What is a Mortise Lock?

A mortise lock(another name is mortice lock) is a lock that can be fitted inside the door-to be cut into the edge of a timber door or steel door. Once installed, when the door is open, you can only see forend, latch and deadbolt. And the strike plate of mortise lock is mounted on the door frame. This lock consists of various parts that work together to secure the door.

What are the Parts of a Mortise Lock?

You may be wondering what makes a mortise door lock. There are many types of mortise lock. Today we will take our European standard mortise lock as an example to illustrate the main parts of a mortise lock. A mortise lock consists of various parts, here are name of mortise lock parts:

1. Lock case

2. Latch & Deadbolt

3. Follower

4. Perforation for cylinder

5. Forend

6. Strike plate

mortise lock parts

Let's look at these components in detail.

1.Lockcase - Mortise lockcase is the main part of mortise lock that contains the mechanism to lock and unlock the door. Material is Galvanize steel SECC, which is anti-fingerprint.

2. Latch & Deadbolt - The main function of latch and deadbolt is to keep the door closed and locked. Latch is a component of a mortise lock that extends from the lock body and latches into the door jamb to keep the door closed. When the door is closed, the latch bolt is extended, and when the key of the cylinder is turned, the latch bolt retracts, allowing the door to open. Deadbolt is a component of a mortise lock that extends from the lock body and provides an additional level of security. It is operated by the knob or key of lock cylinder, When you turn the the key to lock the door, the deadbolt will project, providing added strength and security.For fire doors, latch plays an important role in fire prevention when there is a fire.

3.Follower- A square hole on lockcase for inserting a standard spindle of lever handle. It operates latch when you turn handle. Size of the square hole is usually 8x8mm.

4.Perforation for cylinder -This part is used to match the lock cylinder, our mortise lock are European standard, so the supporting lock cylinder is Euro profile cylinder.

5.Forend - You can also call it faceplate. It’s part of the mortise lock through which the lock is fixed to the door leaf and through which latch bolt and deadbolt pass.

6.Strike plate - Strike plate is mounted on the door frame through which the latch and deadbolt reach into the door frame, to achieve the function of closing the door.

How to Measure a Mortise Lock?

Measuring a mortise lock is essential to ensure it fits the door correctly. For mortise lock dimension, our European mortise lock confirms to DIN 18251 standard. To measure a mortise lock, you need to know the measurements as below:

1. Center distance

2. Backset

3. Lockcase length, width, thickness

4. Forend length, width, thickness

5. Latch projection & Deadbolt projection

6. Follower

mortise lock dimension

1. Center distance - Refers to the distance from the centre of the lock follower to the centre of the profile cylinder perforation.

2. Backset - Refers to the distance from the front edge of the forend to the vertical axis position of the lock follower and hole for profile cylinder.

3. Lockcase length, width, thickness - Length is the overall height of the lockcase only. Width refers to distance from the front edge of forend to the edge of lockcase. Thickness refers to the height of the highest point on the front and back sides of the lockcase.

4. Forend length, width, thickness - It's one part of mortise lock through which latch and deadbolt pass. The forend can have rounded or right-angled corners. Just measure the longest and widest parts of it.

5. Latch projection & Deadbolt projection - Refers to the height of the latch or deadbolt above the forend when locked.

6. Follower- Measurement refers to the size of square hole.

How Does a Mortise Lock Work?

A full mortise lock set include mortise lock, lever handle and profile cylinder. Lever handle can withdraw the latch, allowing the door to open. Thumb turn or keys of profile cylinder is turned to operated the deadbolt to close the door(Thumb turn or keys of profile cylinder can also withdraw the latch)


Different mortise locks have different styles, size and components. No matter what style of mortise door lock, they are very popular in modern society. Mortise locks are known for their durability and reliability. They are available in various finishes, including stainless steel, brass, and chrome. They are also compatible with different types of doors, including wooden door, steel door, and fire doors. The mortise lock is easy to install and maintain, making it a popular choice for commercial projects and public buildings.

If you are in need of European mortise lock, look for a reputable mortise lock manufacturer or supplier, just contact us, we are professional fire proof door hardware manufacturer with more than 10 years experience. Our CE mortise lock is in compliance with EN12209 standard, passed 200,000 test cycles. It is widely used in fire doors of commercial buildings. Look forward to your consultation and cooperation!

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