Sidebars are employed in locks either as a primary or secondary mechanism to prevent rotation of the plug. Though sidebars are also commonly found in wafer locks and disc tumbler locks, for the purpose of this manual we will be looking solely at the use of sidebars in pin tumbler locks. As a general rule, pin tumbler locks that employ sidebars fall under the category of high security locks.
Where sidebars are used as the primary method of blocking rotation of the plug, the pins themselves do not cross the shear line. They are contained within the plug, and have grooves or notches that must be aligned to allow the sidebar to retract into the plug, freeing the plug to turn within the shell. In this design, the traditional combination of key pins and driver pins is replaced by a set of single pins.
Where sidebars act as a secondary mechanism, the pin stacks will, as usual, consist of both a driver pin and a key pin, with the key pin crossing the shear line when the pin stack is at rest. There may be additional pins that interact with the sidebar. Alternatively, alterations of the primary pin stack may allow for the retraction of the sidebar.
Medeco locks have long since employed a unique sidebar system. Their patented system of rotating key pins allows one set of pin stacks to function both as a primary locking mechanism, as well as a secondary locking mechanism that interacts with the sidebar. The pin stacks function just as any common pin tumbler lock, with the driver pins preventing plug rotation. What is different, however, is that the key pins are cut to a chisel shape. Angled cuts on the key will rotate the key pins to a predetermined number of degrees causing gates, or grooves, in the key pins to align with a sidebar that acts as a secondary locking mechanism. In order for the lock to open, each pin stack must not only be lifted to the correct height to line up the separation between key and driver pins with the shear line, but also rotated to line up the gates in the sides of the key pins with fingers on the sidebar. If both of these conditions are not met, the plug is unable to rotate. This system makes picking Medeco locks exceptionally difficult. As if this system weren’t enough, recent additional security features employed in Medeco’s M3 line have made manual picking virtually unattainable in any practical sense. I know of no one currently that can claim the ability to pick, in any conventional manner, a Medeco M3 in less than 30 minutes, provided they do not have any advanced knowledge about the characteristics of the lock. Images of the internal mechanism of a standard biaxial Medeco lock are shown in illus. (needed through needed)
In some locks, such as the those made by Scanlock (no longer manufactured) and Scorpion, there is a completely separate set of pins that work in conjunction with the sidebar. These dedicated pins are not divided into key pins and driver pins; rather, each individual pin has a notch cut in the side which can accommodate the sidebar. When all sidebar pins are lifted to the correct height, the sidebar is free to enter into the notches in the pins and retract into the plug. If the primary pin stacks have been picked the plug is free to rotate in the shell. Of course, this is easier said than done. Detailed photos of the sidebar and sidebar pins from a Scanlock are provided in illus. (needed through needed).