Mechanism
The classical Abloy design consists of a notched hemicylindrical key, and a lock with detainer discs with holes ranging from a hemicircle (180°) to a 3/4 circle (270°). The key is inserted and rotated 90 degrees. Notches, machined to an angle, correspond to complementary angles in the holes of the discs. For example, if the hole is 270°, the key is 180°, and if the hole is 240° (270° minus 30°), the key is 150° (180° with 30° notch) of the circle. In addition, there is a notch in the perimeter of each disc. A sidebar inside an opening in the lock cylinder around the discs, and an edge in the casing obstructs the movement of the cylinder beyond the 90°.
When a correct key is inserted and turned, all the discs will rotate such that notches in the perimeters line up. This allows a sidebar to drop from the cylinder into the groove made by the lined-up notches in the disks, so that it does not obstruct the cylinder, allowing the cylinder to rotate and open the lock.
The lock is locked again by rotating it into the other direction, sliding the sidebar back into the cylinder opening and allowing the straight edge of the key to return the discs to the scrambled "zero" position.
Read more about this topic: Disc Tumbler Lock
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