Most key systems work with a pin tumbler lock. A key works as it lifts up a key pins within a keylock and all these key pins are different sizes. The key is unlocking as it is pushing the right set of grooves to lift the key pins to the correct height. With that simple example you can come to understanding of how you key system works. All that must happend for any standard pin tumbler to be converted for a master key system is to add a master wafer (aka master pin) between a driver and key pin. A master wafer is virtually a small hockey puck shaped pin. Once it is in place, the pin stack will have two shear lines. A shear line for a pin stack with a master wafer below or above the line.
Most large institutions don’t want their employees to carry around large number of keys. Similarly, these institutions would like to restrict access based on an individual’s standing, and responsibility, within the establishment. A master key system will allow for different levels of restricted entry. When a master key system is finished there may be a graduated level of access. In the example of a property manager, one tenant’s key will work on their lock but not on the neighbor’s lock. However, the property manager will have one key that works for both locks. This can work to create a number of possible keys. Say there are five chambers in the lock and five active pin stacks. If each one of those stacks has a master wafer, then each chamber will have two possible shear lines. That is 2 x 2 x 2 x 2 x 2, or two to the fifth power (2^5), which equals a total of 32 possible unique keys. Of those 32 possible keys, only two keys need to be made. One will be for the person with access to what that lock is securing, and another for the person that has access to what every lock is securing in the location.
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