ABLOY: The Rotating-Disc Cylinder from Finland

Emil Henriksson and the 1907 Invention

ABLOY's history credits Emil Henriksson, an office-machinery mechanic in Helsinki, with inventing the "detainer disc locking cylinder" in 1907. ASSA ABLOY's own history puts the idea this way: a very secure lock could be built from rotating discs, "which must be set, using a key, in a particular position for the lock to be opened."

The earliest patent text we could read is Henriksson's American one. U.S. Patent 1,514,318, "Safety Lock," was filed May 29, 1919 and granted November 4, 1924. It names "Emil Wilhelm Henriksson, of Helsingfors, Finland" (Helsingfors is the Swedish name for Helsinki), as the inventor, with the patent assigned to Josef Herman Nordqvist of the same city. The patent says the lock suits "doors, safes, boxes and the like" and can also serve as a padlock.

A University of Helsinki history of Henriksson gives the Finnish patent dates as an application in July 1918 and a grant on February 15, 1919. We could read that article only through a search extract, so treat those two dates as reported rather than checked against the Finnish patent itself.

From Workshop to Company

ABLOY's published timeline and ASSA ABLOY's history agree on the early milestones:

ASSA ABLOY describes "Abloy" as a shortened form of the original company name. ABLOY's 2022 brochure gives the company's address as Joensuu, Finland.

How a Disc Detainer Works, in Principle

Henriksson's patent describes the core idea in plain terms. Inside the cylinder sits a series of discs, each with a notch, separated by spacer discs. The key's shank is shaped to fit the openings in the discs. As the key turns, it pushes or partly turns the discs "one after another." Only the correct key leaves every notch in the same position. When the notches line up, a locking element can drop into them and the cylinder can turn.

Compare that with a pin tumbler lock, where the key lifts pins to a shear line. In a disc detainer, the key rotates each disc to an angle. The idea of a separate bar that can only move when every element is aligned is shared with sidebar locks.

ABLOY describes the practical result as a mechanism "based on the use of rotating discs instead of traditional springs and pins," and its cylinder page says the design has "no springs or pins to wear, jam or freeze." Those are the manufacturer's own words.

Cylinder Platforms

ABLOY's 2022 key-systems brochure shows a "cylinder system evolution":

ABLOY's own documents do not agree on two of these dates. An older ABLOY history brochure gives 1976 for PROFILE and 2012 for PROTEC². This article reports both and does not choose between them.

The PROTEC launch year of 2001 also appears in a 2005 technical article by Dutch collector Han Fey. The same article describes PROTEC as the newest step in a line that runs through DISKLOCK, DISKLOCK PRO, and EXEC, all built on the rotating-disc principle. ABLOY's brochure makes the same point more simply: every one of its cylinder platforms is "based on the rotating disc cylinder mechanism."

Electromechanical Locking: CLIQ

In May 2001, ASSA ABLOY announced a technology called CLIQ that combined mechanics with electronics. In the announcement's words, "the key must not only fit mechanically, its identity, stored on a microchip, must also be approved by the lock." Each key is unique, so access rights for a lost key can be withdrawn. ABLOY's history brochure lists the electromechanical PROTEC CLIQ key system under 2006. It describes the system as a mechanical lock combined with "low-power electronics" so that access rights can be managed remotely. For the wider idea, see access control.

Patents and Key Control

Like other high-security makers, ABLOY ties key control to patents on its keys. Its 2022 brochure says that "duplication of patented keys is strictly controlled" and that "the security level of additional keys varies from local service to highly restricted procedures." The same brochure gives patent terms for current platforms:

• SENTRY and NOVEL: patented until 2027
• PROTEC²: patented until 2031

Patents expire, so the protection is time-limited. The general principle is covered in restricted keyways. For the role of key control in ratings, see high-security locks.

ABLOY's brochure also notes that "it is the customer's responsibility to define the required level of security," and that a locking system is only one layer alongside key management, alarms, and physical security. No cylinder is secure on its own; the door, frame, and strike plate matter too.

Master Keying

ABLOY's brochure says a variety of its products "can be keyed into one master key system," and describes multi-level systems laid out by building, floor, department, or user role. The University of Helsinki history makes a similar point about the original disc design, saying it made master keying practical. See master keying.

Related Topics

• Disc detainer locks: the mechanism ABLOY is built on
• High-security locks: ratings, key control, and the ABLOY example
• Sidebar locks: the shared "all elements aligned" principle
• Pin tumbler locks: the mechanism disc detainers replace
• Key control and restricted keyways: patent-backed key restriction
• Master keying: multi-level key systems
• Medeco: another patent-based high-security cylinder
• EN 1303: the European cylinder standard
• Yale & Towne: another lock maker now in the ASSA ABLOY lineage

Sources