Schlage Locks: Setting the Industry Standard

Residential and Commercial Security

The Parts of a Pin and Tumbler Lock Key

If you’ve ever wondered how a key works, it helps to start with a diagram of a typical pin and tumbler type key. Pin and tumbler locks are the most common types of locks in the world. They can be found on virtually every home and commercial property in the industrialized world, both inside and out.

This Schlage Key diagram is labeled, and we will examine each part individually:

Diagram of a key

Diagram of a key

1) Head: This is the top of the key, the part that you hold on to when inserting the key into the lock cylinder.  The head needs to be big enough to support the force of the rotation of the key, otherwise the key may break off inside the lock cylinder.

2) Shoulder: Keys may be cut with one or two shoulders.  The shoulder(s) is like a guard which prevents the key from being inserted too far into the lock cylinder.

3) Shaft: This is the part of the key that gets inserted into the lock cylinder.  This is where the cutting takes place.  Most keys have cuttings on only one side of the shaft, but some have cuts on both sides.

4) Ridges/Teeth: The raised/pointed cuts on the key shaft.

5) Notches: The “valleys” between the ridges/teeth.

The ridges/teeth and notches are the most important parts of the key.  It is these cuts in the key shaft that determine whether a key will open a particular lock or not.  A key will only open a lock if its cut matches the pins inside the pin and tumbler lock.

When the matching key is inserted, the gaps between the red (key) pins and the blue (driver) pins

When the matching key is inserted, the gaps between the red (key) pins and the blue (driver) pins align.

A key that does not match up will do one of two things.  Either the shaft will not go into the lock cylinder at all, or the key may be inserted, but it won’t be able to rotate.  Forcing it to rotate will break the key shaft off and/or damage the key cylinder.

By Jenny Schweyer


January 28, 2009 - Posted by | Commercial and Residential Security | , ,

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