Change lock

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Open mortise lock - the change is visible on the left side: an elongated, rod-shaped and in this case two-part component with a central joint. If the nose (the driver) of the lock cylinder (not inserted in the picture) has pushed the bolt all the way to the right after turning the key twice, then the lower part of the change has also moved so far to the right that the nose at the next Rotation from below against the change. The lower part of the change passes the impulse on to the upper part via the joint. Because of the second joint on which the upper part is mounted, it rotates to the right. Since the top end of the change is latched into the latch, the latch also moves to the right and releases the door.

The designation of the parts of a mortise lock . Most modern mortise locks have the function of a change lock.

A mortice lock is a door lock , the lock latch with the key may be operated (shift function according to DIN 18251-1); this means that no handle is required to open the door .

When the extended bolt has been completely withdrawn into the lock by turning the key, the key "changes" its function and it now also pulls back the latch.

Apartment and house doors are mostly not provided with a handle on the outside, but with a permanently mounted knob so that the door cannot be opened from the outside even if it has just fallen into the lock and not been locked. The door must be equipped with an interchangeable lock so that it can be opened from the outside with the key alone.

However, there is a risk here that the door can no longer be opened from the outside if a key has been left inside and the door falls into the lock. Normal lock cylinders prevent the key from being fully inserted if a key is already on the other side. Care should therefore be taken to use a double cylinder that has a hazard function. The interchangeable lock can also be operated here if a key is on the opposite side.

Names of the individual parts

A square pin is used to transmit power from the door handle to the follower . It is also called a mandrel pin or pusher mandrel. If the square pin of a change lock is only operated from one side, it does not necessarily have to extend beyond the handle follower to the opposite side of the door leaf. It can be attached to one side of the door handle and pushed into the door lock together with it.
In most cases, however, a continuous pin is used that extends into the knob on the opposite side and is freely rotatable there.
The special pin of a change lock is also called a change pin.

Door fittings that do not have a door handle on the outside and can therefore be opened simply by using the key are also referred to as change fittings . A change set consists, for example, of two door plates , a door knob and a door handle, which in this case is also called a change handle.

Mortise lock without change

Footnotes

1. ↑ Change pen in the Fermatec security technology dictionary
2. ↑ Change set in the Fermatec security technology dictionary