Mortise locks work by extending a solid bolt from the lock mechanism into a specially cut pocket in the doorframe, known as the mortice.
Understanding the Mechanism
Mortise locks are a type of lock system installed within a door, rather than mounted on its surface. They are known for being one of the most readily available and secure types of locks. Their name comes directly from their core functional principle: the use of the mortice.
Here's a breakdown of the key components and how they interact:
- The Lock Body: This substantial metal casing fits into a large, rectangular pocket cut into the edge of the door itself. It contains the internal workings, including springs, levers (in traditional locks) or gears, and the locking bolt.
- The Bolt: This is the solid metal bar that extends from the lock body into the doorframe to secure the door. It is typically operated by turning a key or a thumbturn.
- The Mortice: This is a pocket or recess that is cut into the internal face of the doorframe directly opposite the bolt when the door is closed.
The fundamental action of a mortise lock is simple:
- When the lock is engaged (either by key or thumbturn), the bolt is pushed or thrown outwards from the lock body in the door.
- This bolt travels across the gap between the door and the frame.
- The bolt then enters and slots securely into the mortice pocket cut into the doorframe.
- When the bolt is in the mortice, the door is unable to move and is securely locked. The door cannot be opened until the bolt is retracted from the mortice, typically by turning the key or thumbturn back in the opposite direction.
This design, embedding the lock body within the door and securing it into a matching pocket in the frame, makes mortise locks very robust and resistant to forced entry compared to surface-mounted alternatives.
