Lock (technology)

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A lock is a device that is used to allow selected people access to certain areas and to deny other people this access.


The lock does not do this on its own, but is used together with other facilities, e.g. B. Doors, grilles, special bolts, lids, chains and more.

  • The necessary identification of the authorized access persons is usually done with the help of a key . This can work mechanically and / or electronically or be transferred to the lock as a combination of characters. This procedure assumes that only authorized persons are in possession of a valid key.
  • Self-locking locks close automatically after a certain period of time after opening if they are not used.
  • Locks with compulsory locking allow the key to be removed only after it has been locked.

Locking systems

Locks are differentiated based on the locks used and their design:

Drop bolt lock

The latch bolt lock is the oldest known lock in human history. The first references to drop bolt locks are images on Akkadian seals from the 3rd millennium BC, on which the god Shamash is depicted with a key in his hand. Drop bolt locks were also used in ancient Egypt . The oldest original find was made in the Palace of Khorsabad and dates back to around 750 BC. Dated.

In the upper area of ​​the lock there are pins and latch bolts that fall into holes in the bolt due to their own weight and block them. The brush-like key has prongs that lift the individual latch bolts and thus release the bolt again.

The variation results from the fact that different numbers of latch bolts can be installed in the various locks at very different distances. From a technical point of view, the latch bolt lock is the direct forerunner of the pin lock .

Drop bolt locks are still produced and used in certain regions of the world ( West Africa , Anatolia , Faroe Islands ).

Spring lock

Spring lock, bronze, 12th-14th centuries Century. Bremen, Focke Museum

The spring lock, usually a padlock, consists of two parts. The locking spring (expanding spring) that holds the two parts together is hidden inside. It looks like the barb on an Indian arrow. To lock, you press both parts of the lock together, while the locking spring is pushed through a hole, spreads on the other side and thus holds the lock parts together.

To unlock you have to push the key into the keyhole. The key presses the locking spring together again and you can pull the two parts of the lock apart.

Spring locks have been in use in today's Germany at least since the 1st century BC. Known. The oldest specimens were discovered in the oppidum of Manching , a Celtic town near Ingolstadt . Spring locks are still made in countries like India , Morocco , the People's Republic of China and Iran to this day.

Castles in the Roman Empire

Roman ring spanners from the 2nd or 3rd century

Like other technical achievements of the Romans, the Roman castles probably have Hellenistic forerunners, of which, however, hardly any archaeological evidence is known. However, numerous keys have survived from Roman times. The upswing in lock manufacture in Roman times was due on the one hand to the spread of metalworking in this era, and on the other to the urban way of life of the Romans, which encouraged the use of locks.

Occupation lock

Fig. 1: Tumbled key a: Beard b: Tube c: Die d: Diamond or ring e: Little head. Fig. 2: Crew

Crews , often referred to as Fully equiped or tangles referred to obstacles, iron rods or plates, which are installed inside the castle of the rotational plane of the key are. The complex patterns that are sometimes found in the key beards of ancient keys are used to circumvent these obstacles. The lock can only be unlocked if the key bit matches the shape of the crew.

The crews are the only security features in castle construction that survived the fall of the Roman Empire. Throughout the Middle Ages and up to the great innovations of the 18th and 19th centuries, the occupation remained the only effective security feature known in palace construction.

Bit lock

Tumbler locks are mostly found in apartment interior doors . They have only a barrier in the form of a plate before closing channel on which to transmit only the key with the right profile, and are protected by lock picking already with simple tools such as a Dietrich to open. 64 different profiles are common for tumbler locks in Germany. The locking bolt of a commercially available tumbler lock is only blocked with a steel spring, which is lifted from the lock by the closing surface of the key so that the key can move the bolt further. Tumbler locks in apartment interior doors usually have a snap bolt (latch) in addition to the locking bolt.

Bramah lock

Bramah key
Bramah lock

After almost all ancient castle constructions had been forgotten in the early Middle Ages, Joseph Bramah was the first to reintroduce fundamental innovations in security technology after a phase of stagnation that had lasted from around 450 AD.

The heart of the Bramah lock are metal plates that are notched at a certain height and arranged radially around the keyhole. The end of the key stalk has incisions of different depths.

These push the plates just deep enough into the lock that the notches around the cylinder are at the same height so that the key bit can turn it.

The lock invented by Joseph Bramah in 1784 lost more and more of its importance as a front door lock in the 19th century, as many components had to be laboriously manufactured by hand and it was therefore much more expensive to manufacture than the tumbler locks . In terms of security, however, it was clearly superior to its competitors and was therefore mainly used in vault construction.

In 1851, 41 years after the inventor's death, Alfred Charles Hobbs was the first to succeed in overcoming a Bramah lock. However, it took him 16 days to do this, while he opened the equally vaunted Chubb lock in a few minutes.

Guard lock by Robert Barron

Simple locks with tumblers are known from the Gothic period around 1300. The acorns raised by the key could also be called tumblers in the case of the latch bolt lock with a rotary key.

In 1778 the Englishman Robert Barron was the first to patent a tumbler lock. The idea of ​​installing tumblers in a lock was a radical innovation. The basic principle was later to be further developed by Chubb and still forms the basis for the construction of safe locks today.

In the barron lock there were two lever-like movable tumblers, brass sheets on which a pin is soldered. The latch had a horizontal slot, or channel, with notches up and down that the tumbler pins snap into and hold in place.

The key bit in turn had notches that lift the tumbler plates just enough that the pins can be lifted out of the notches and can slide through the channel in the bolt. If the incisions in the key bit were just a little too high or too low, the bolt was blocked and the lock could not be opened.

However, Barron was not yet consistent in implementing his idea and he stuck to the tried and tested by still providing his lock with a crew and adding the tumblers to this only as an additional security element.

Chubb lock

Animation of a Chubb lock

The English engineer Jeremiah Chubb developed another lock that is widespread worldwide with the Chubb lock , which he patented in 1818. The basic principle of the guard locking by Barron was also further developed at the same time by the Italian Tossi, who obtained a patent for a lock that was almost completely similar to the Chubb design. Such castles are also called Tuscan after Tossi . However, it was Chubb who helped the tumbler lock to its international reputation.

Chubb reversed the Barron principle, making it possible to use any number of tumblers. In his lock, the pin was attached to the bolt and the tumblers were provided with the slots as guide channels.

Like many 19th century designers, Chubb was so convinced of his invention that he offered a heavy cash prize to anyone who managed to open his lock without the accompanying key. The lock had previously been tested by experts from the British government. When a convicted burglar took up the challenge, Chubb's invention was trusted so much that if he succeeded, he would be released from prison. The former locksmith struggled unsuccessfully for over a week.

On July 22nd, 1851, the American AC Hobbs opened the lock on display in the Crystal Palace in just 25 minutes during the great world exhibition in London , without damaging it. He used a method later named after him ( Hobbs' opening method ). This is still used today by locksmiths around the world . With an instrument he developed himself, he was able to bring the tumblers into the correct opening position.

Disc lock

Key for a turntable lock

Disk locks are often found in furniture and wherever a small installation depth is required. However, disc locks are also used in automobiles and as bicycle locks . Spring-loaded discs serve as the locking mechanism. Without a key, the panes get caught in the cutouts provided and block the lock. The key holds the discs in the center of the core so that it can be turned to open. The same locking mechanism, used by both sides, is found in the double disc lock. The small thickness of the panes allows either a high density or a low overall depth. A suspension of the discs on an axis different from the locking channel turns the disc lock into a chubbing lock.

A completely different and significantly safer implementation of the disc lock uses unsprung rotating discs. This type of lock can be found z. B. Widely used in Finnish door locks and also in better padlocks, bicycle and motorcycle locks.

Double-bit lock

These keys belong to locks of the Kromer principle

The protector lock of the German Theodor Kromer was patented in the German Empire in 1874. Unlike its rival, the Bramah lock, it could be made completely by machine and was therefore cheaper. The protector lock is essentially a guard lock. The tumblers are not suspended like a lever, but are located in a rotatable core. The key has two beards and thus has a double effect on the tumblers and thus achieves a locking variation of 88 million.

Seldom used as a door lock, double-bit locks are usually found in lockers or in vault construction.

Pin lock

The majority of all locks today are pin locks. They were by Linus Yale jun. Invented in New York in 1865 . Several pillars of pins (pin pairs) pressed into the core by spring force , divided into housing and core pins, block the core until they are all pressed into the housing by the key so far that the division is due to the shear between the core and housing. Commercially available pin locks have 5 or 6 pin columns. Additional subdivisions in locking systems ensure that different keys can unlock the same lock.

The profiling of the keyhole and the key bit is also used to vary the locks; in locking systems, in addition to the pin divisions, the profiles can also be used to differentiate the locking authorization.

Most pin locks are made as a brass lock cylinder, but there are also expensive and secure stainless steel designs.

Dimple lock

Dimple wrench

The dimple lock is a sub-form of the pin lock. Here, indentations are drilled into the flat sides of the key, into which the pins slide, the closing surface of the key is thus perpendicular to the alignment of the pin columns. Dimple wrenches are reversible keys , so they have the same bores on both sides and can be inserted into the locking channel with their top and bottom facing the pin columns in order to open the lock. The advantage is that there is more space available on the flat side of the key and up to 25 pens can be used. At the same time, the use of opening tools is made more difficult. In addition to the holes for the pin tumblers on the flat sides, additional holes for horizontal and vertical profile control pins are often accommodated on the narrow long sides.

Tubular shaft lock

Tube locks (tubular locks), which are often found on fuses for portable computers, as bicycle locks or in key switches in alarm systems, have pin columns that are arranged in a circle around the shaft; the key, in the form of a short tube, has cutouts in which the pins are held at the correct height.

Cylinder lock

Lock cylinder of a cylinder lock (pin lock)

The cylinder lock is based on the concept of separating functions. The lock itself causes the actual locking (locking), while the function of the drive of the bolt or the latch as well as securing the locking mechanism against foreign keys (or other unauthorized opening attempts) is taken over by the lock cylinder (often a pin lock ).

For the different types of locking cylinders, see: Profile cylinder , oval cylinder and round cylinder .

Number combination lock (ZKS)

Travel Sentry Lock.jpg
Combination lock
Combination lock

Number combination locks (more correctly: digit variation lock , because digits and not numbers are varied (with sequence and repetition)) can be found in mechanical versions on suitcases, as bicycle locks as well as on safes or gun safes . Mechanical combination locks are usually based on rotating metal disks that are provided with a notch. The individual discs are rotated into the correct position by a mechanism, a function bar engages in the notches and the mechanism is unlocked.

As a mechatronic variant, it is less common on doors and safes. The electrical version can be found on some car radios and alarm systems . The mechanical variant works with discs that have locks on all numbers except those of the correct combination. The mechatronic version corresponds to an electronic combination lock (ELO) triggered by a servo motor or a similar device.

Some locks on briefcases or bicycles can be set to a desired number via a mode of operation that can only be carried out when the door is open, which means that several locks can be locked with the same lock very easily. Good bicycle locks only transfer the number indirectly and therefore not under tension to the locking mechanism, so that these are considerably more difficult to try from 0-999 (9).

ZKS can be counted among the standard locks, as the combination for opening can be made easily accessible to a larger group of people.

The ZKS developed in the second half of the 19th century and goes back to the letter lock developed by Giovanni da Fontana in 1420 .

Magnetic lock

Mechanical magnetic locks work like pin locks and use opposing magnets to lift the spring-loaded pins: Magnets in the lock and in the key lift the pins so that they can be unlocked. Further developments are based on rotating magnets in the cylinder core. The exact alignment of the magnets on the key is queried. This enables a very large number of variations in order to be able to implement the most complex locking systems.

Mechatronic locks

The interlock for a mechanical door or flap is always mechanical. The mechanical function of the bolt can be used in the event of a chip or power failure. The electronic function should work without wear or contact.

Mechatronic locks usually consist of two main modules: an electromechanical lock on the inside and an operating unit on the outside of a door. To connect the two components, a hole has to be drilled in the door or in the lock for a cable. This solution requires a voltage source for the electronics and the lock with relay and bolt, in the case of some products also in the key or code transmitter. Modern code generators work with piezo cascades as a voltage source. Alternatively, the code transmitter can also be supplied with voltage by the receiver via the air interface after the ID medium has 'woken up' the transmitter / receiver in the lock through the approach.

With some makes and design variants there is a risk that someone could gain access to this connection. As a safeguard, however, some mechatronic locks are designed in such a way that the mechanics are completely blocked as soon as manipulation takes place. Opening, even by authorized persons, may then no longer be possible.

Radio lock

Radio locks are mostly used in combination with electromechanical locks. A further development of this combination are mechatronic radio locks in which the electronic and mechanical functions are integrated and miniaturized. Radio locks are built into millions of automobiles.

Newer solutions are radio locks, which unlock the lock after prior authentication and data transmission with a secure protocol ( Bluetooth protocol) to the lock. The Bluetooth master will be, for example, a mobile phone or another code generator, the lock then forms the Bluetooth client or vice versa. Corresponding products have been on the market since the introduction of corresponding industrial standards ( e.g. BlueID technology ).

Motor lock

A motor lock closes the bolt by means of an electric motor. There are internal versions (the size of a lock cylinder) and external versions that are suitable for lock cylinders that have a knob (or similar) on one side. The advantages of motorized locks are that you cannot forget to lock and that access can also be made with another system ( combination lock , transponder , chip card, etc.).

Digital locking cylinder

A digital locking cylinder has the shape of a normal locking cylinder, but is activated by means of a transponder . There is (mostly) no normal keyhole. It is powered by one (or more) battery (s). A digital, battery-operated locking cylinder from SimonsVoss (today SimonsVoss Technologies GmbH) was presented for the first time in 1997.

Vexing lock

A concoction lock is a device in the form of a lock, which can be opened with a concealed / camouflaged device if the lock has not previously been locked with a key. The oldest known trick or puzzling locks are the Roman padlocks with mask lids from the 2nd to 3rd centuries.

Through lock

The through lock is a Berlin invention. It is also called a forced locking lock . It was invented around 1912 by master locksmith Johann Schweiger . The through lock is still produced today in Berlin-Biesdorf at KERFIN Schlossproduktion u. Metalworking made. There is a matching key for the mortise lock .

Electro-mechanical locks with Knock Code technology

Locks with knock-code technology are designed to prevent the risk of "eavesdropping" on the code transmission or the possibility of unauthorized persons entering the opening code on a trial basis. Such a lock is mounted on the inside of a door or container etc. and has no through-holes for mechanical keys or cables on the outside. This means that there is no access to the lock, which eliminates the disadvantage of electronic locks just described.

Using a code key, the "KnocKey", knocking signals are transferred to solid materials. The knocking signals of such a sounder form the "knock code" or "knock code". The coding is contained in the combination of the time intervals between the individual knock signals. So it is not the knocking tones themselves that are decisive, but rather the variable periods of time in between, the changes of which are small enough that the human ear can no longer distinguish them. Due to the algorithmically encrypted variation possibilities, there are billions of different combinations. The system works with all solid materials: wood, glass, plastic, metal and reinforced concrete.

The trivial patent was registered worldwide in 2001 by the inventor Ilan Goldman. One possibility would attack, for example, to provide a solid-borne sound - microphone to be deposited and a suitable recording device inconspicuous so that the knocking may be recorded. This problem of the so-called replay attacks is countered by using knock codes in the form of one-time keys (note: locks that are " keyed alike " are not advisable in this context), but a secure transmission channel for code transmission can be used do not provide this technology.

Shoot bolt lock

The shoot bolt lock is a lock in which the locking mechanism is not actuated directly at the locking point. Shoot bolt locks are usually released for unlocking or locking by actuating a lock cylinder . The locking elements (rods, bolts) are then z. B. moved via a rotary handle or rocker arm. It is used e.g. B. in garage doors, document cabinets, generally where the actuating force for the tumblers cannot be applied by the lock cylinder itself without the risk of damage to the cylinder and / or key.


Antique ornate iron padlock in a temple in Kathmandu (Nepal)
Brake disc lock
  • padlock
  • Box lock (lock in the lock case on the inside of doors or furniture and chests )
    • Mouse box lock (box lock in which the latch is not pulled into the lock, but lifted)
  • Mortise lock , also mortise lock, for doors - see also: door lock
  • In the car
    • Ignition lock with steering wheel and / or immobilizer
    • Doors and tailgate with central locking with radio remote control
    • For the roof rack with the fastening screws
  • With the motorcycle
    • Ignition lock with handlebar and / or immobilizer
    • Compartments and cases (some with central locking and radio remote control)
    • Case carriers at the fastening screws
    • Brake disc lock that is attached to the brake disc .
    • With a key or combination of numbers and a chain that is led through a frame, a wheel and possibly also around or through a solid object.
  • With the bike
    • With a key or combination of numbers and a steel cable that is guided through the frame, a bike and the hopefully permanently mounted bike stand.
    • With a chain (usually padded with a tube) and a padlock .
  • Key switch, switch with integrated lock that can only be operated with a key; z. B. in elevator systems
  • A lock is built into the handcuffs


Individual evidence

  1. ^ German dictionary of the Brothers Grimm, Volume 3, 1859, Col. 189
  2. Bicycle lock with turntable cylinder
  3. Castle (technology). In: Brockhaus Encyclopedia Online. NE GmbH | Brockhaus, January 17, 2020, accessed on January 17, 2020 .
  4. BlueID technology

Web links

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