Property managers and maintenance staff who work in large apartment buildings do not want to have to carry around a separate key for each and every unit. Locks can be keyed in a way that allows them all to be opened with a single master key, which makes things easier for people who need to be able to gain access to each apartment to make repairs.

The Cylinder Lock

The most common type of lock is the cylinder lock. In that design, a key turns a cylinder, or plug, which turns a cam. If the cylinder is turned in one direction, the cam pulls in on the bolt and the person can open the door. If the cylinder is turned in the opposite direction, the cam releases the bolt, a spring moves it into place, and the door cannot be opened.

The Pin-and-Tumbler Lock

The inside of a cylinder lock is designed in such a way that only the right key with the right design can open it. One of the most common types is a pin-and-tumbler lock. It has a series of small pins that vary in length and are arranged in pairs. The pairs of pins are arranged in a shaft that runs through the central cylinder plug and extends into the housing around it. Springs are located at the top of the shafts and hold the pairs of pins in the right position.

If a key is not in the lock, the bottom pin is completely inside the plug, and half of the upper pin is in the plug and half is in the housing. This prevents the plug from turning.

When a key is inserted in the lock, the pins are pushed to different positions so that the point where two pins meet is perfectly aligned with the space where the cylinder and housing meet. This point is known as the shear line.

Master vs. Change Keys

Some locks can be opened with two different keys. A change key will only open one lock, but a master key will open them all. In those locks, a few pairs of pins have a third pin called a master wafer or spacer separating them. If there is a third pin, the pins can be positioned in two different ways to open the lock. This allows someone to use a master key to open all the locks, but a change key will only open one lock so that residents cannot gain access to each other’s apartments.

All American Locksmiths can key many locks in a building so they can be opened with a master key. If you own or manage an apartment building and need to have access to all of the units to make repairs or to deal with potential emergencies, we can key them all so they can be opened with a single key. Contact All American Locksmiths today to learn more about our master key services.