Disc tumbler lock
Encyclopedia
Wafer tumbler lock
A wafer tumbler lock is a type of lock that uses a set of flat wafers to prevent the lock from opening unless the correct key is inserted. This type of lock is similar to the pin tumbler lock and works on a similar principle. However, unlike the pin tumbler lock, the wafer is a single piece...
or a pin tumbler lock
Pin tumbler lock
The pin tumbler lock is a lock mechanism that uses pins of varying lengths to prevent the lock from opening without the correct key...
, this mechanism does not use springs. From a security standpoint, the disc tumbler lock cannot be bumped
Lock bumping
Lock bumping is a lock picking technique for opening a pin tumbler lock using a specially crafted bump key. One bump key will work for all locks of the same type.-History:A US patent first appears in 1928 by H.R. Simpson called a "rapping" or bump-key...
. Because they do not contain springs, they are better suited for areas with harsh conditions and are often used at outdoor locations like railroad and public utility installations.
Disk tumblers are difficult to pick and are sold as "high security" locks. Picking the lock is not impossible, but requires a lot of time, a dedicated, professionally made tool and special expertise. This level of difficulty tends to drive attention to alternative methods of gaining entry. The locking mechanism can be disabled destructively by drilling into the lock to destroy the sidebar. Anti-drilling plates can be installed to prevent this.
In areas of the world where this type of lock has historically been rare or unknown, the term "disc tumbler lock" is sometimes mistakingly used to refer to wafer tumbler lock
Wafer tumbler lock
A wafer tumbler lock is a type of lock that uses a set of flat wafers to prevent the lock from opening unless the correct key is inserted. This type of lock is similar to the pin tumbler lock and works on a similar principle. However, unlike the pin tumbler lock, the wafer is a single piece...
s, which are much less secure and are commonly found on desks and file cabinets.
The lock was invented by Emil Henriksson in 1907 and manufactured by Abloy. Another popular brand in Malaysia is Solex. ABUS
ABUS
ABUS is a German lock manufacturer founded in 1924, based in the town of Wetter in North Rhine-Westphalia. The name ABUS is an acronym for August Bremicker und Söhne KG....
manufactures padlocks and cycle locks employing disc tumbler cylinders in their Plus line.
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 slot, 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.