Safety Engineering

Safety Engineering
Safety Engineering
Video: Safety Engineering
Video: Safety Engineering 2023, February

This article will consider the widespread types of mechanical locks and cylinders used in metal doors, their classification, types, methods of application and principles of operation.


One of the foundations of security in metal doors of any manufacturer is locks. This may seem paradoxical, but most often the cost of a good lock exceeds the cost of the door in which it is installed, several times, or even an order of magnitude. Your safety and peace of mind are directly dependent on the quality, strength and durability of the lock. Convenient and easy to use, with a nice key, but at the same time a highly secure lock - an ideal, but alas, not always an option.

The main reason for using locks, according to one or another parameter that does not meet the above conditions, is the price. Most door manufacturers try to keep their products as cheap as possible. As a result, we get a good door with bad locks. And many do not have enough money for expensive imported machinery.

It should be admitted that imported locks are still superior to ours in most technical characteristics (well, and at a price), but not every imported lock is better than a cheap domestic one.

In recent years, there have been a lot of Chinese and Italian locks on the market that are not suitable for use in metal doors. These locks, comparing favorably with Russian ones in external design, are mostly intended for use in wooden doors, where the load and requirements are lower. The use of these locks entails a lot of problems, such as broken handles and failure at the most inopportune moment.

Domestic locks are also not all suitable for metal doors, due to the fact that during their development (which was sometimes 10 - 20 years ago) metal doors did not exist, and the designers did not take into account the increase in loads when using a lock in a heavy door. Locks of similar models are still produced today. Attracted by the cheapness, many firms install them in their doors, causing the consumer to suffer. The main feature by which a lock of this class can be distinguished is the manufacture of the entire lock, or part of it (for example, handles) from a soft or fragile material such as silumin. The use of plastic in the lock mechanics is also unacceptable.

Next, we will consider the main types of locks by their purpose, by the type of installation and the principle of the secret mechanism.

Locks are installed on the door in different ways. They can be embedded, applied or hung. Next, mortise locks will be considered as the most common and reliable.

By purpose, the locks are divided into two groups

  • Fixing - locking (lock with handles, bottom lock) Locking (handleless lock, top lock)

A distinctive feature of the first group is the presence of handles that remove the tongue - the retainer. In the vast majority of doors of any production, such a lock is installed. The meaning of its action is simple - to fix the door in the closed position. A door without this lock, when locking, you will have to hold it with your hand, knee or … (belly). It is understood that this lock also has a locking part (i.e. a secret part and a bolt). A device designed only to fix a door is called a latch.

The second group of locks does not have a retractable tongue - a latch and serves only for locking.

In most domestic entrance doors, two locks are used: locking - locking and locking.

According to the principle of the secret mechanism, the locks are also divided into two groups:

  • Lever (or flat - leveled) Cylinder (larval or pin)

Lever locks

Lever locks are often, unknowingly, called safe locks, since earlier locks of this particular group were almost always used in safes (if you do not take into account rotary coding locks, which are not used in doors and will not be considered). In fact, a safe lock should be called a lock with an increased level of protection and secrecy of the mechanism. A real safe lock must work in more severe conditions, for example, the lock must open well - close even after a fire. This is achieved due to the fact that there are no elements subject to combustion in its mechanism. For example, there are no springs and parts made of spring wire (which anneal at high temperatures and cease to function). Often, a safe lock is called a lock with round locking elements (crossbars), which is a mistake.

Types of keys for lever locks

The leveler system of the castle is the most ancient and was used in a simplified form in the first castles invented by man.


The basis of its action is a set of plates (levers) which, lining up under the action of the teeth (beard) of the key in strictly defined positions, allow turning the lock mechanism. The mismatch of at least one levers with the "correct" position makes it impossible to open the lock. The larger the levers, the more difficult it is to pick the lock. With sufficient protection of the mechanism from drilling, with high-precision manufacturing of levers, with a large number of them and if there are special teeth on them (making it difficult to work with a master key), opening a lock of this type is very difficult even for a professional bear-kitten (a specialist in opening locks). The disadvantage of this system is the relatively large key and the inconvenience in replacing the mechanism (for example, in the event of a key loss). The whole castle has to be changedsince the levers and the drive of the locking elements are interconnected. (This problem was solved by the Italians, who produced several types of locks with a replaceable set of levers)

Opening of the lever type lock

This type of locks can be opened using special picks. For such constipation, burglars use flat L-shaped plates and hooks. It is thanks to complex manipulations with them that it is possible to lift all the plates of the secret mechanism. Accordingly, the larger the levers, the higher the secrecy of the lock and the more difficult it is to open it. It would seem that everything is simple, but this is far from the case. In addition to the dexterity and sensitivity of the hands, the professional must thoroughly understand the interior of the castle.

Cylinder lock system

The cylinder lock system is a product of modern technology and appeared in the 20th century. Locks of this type are more common these days due to their ease of use and replacement. In fact, if necessary, it is not the lock mechanism that changes, but only its secret part - the cylinder, known to most as the larva. This element of the lock, transmitting the turn of the key to the mechanism, is a secret (encryption) device that works with only one specific key combination. The action of the mask is based on the principle of building a combination of heights of small cylindrical elements (hence, apparently, the name). As in the lever lock, the mismatch of at least one element makes opening impossible. The degree of secrecy is determined by the number of cylindrical elements, the accuracy of their manufacture, possible positions in height,the location inside the mask and the ability to access the master key. There are larvae that use plates rather than cylinders. Such masks are more often used in cars (door, trunk, ignition), since they are less sensitive to dirt and water, but are considered less secret.

Secret mechanisms of the Abloy type (Finland) stand somewhat apart. The key in this lock is semicircular with beveled cuts of different depths (such keys are called Finnish). In them, the code is based on washers rotating in a cylinder. This is a very tamper-resistant type of lock. According to the degree of secrecy, he belongs to one of the first places. It is extremely difficult to open it by picking a key or a master key. It's easier to break. True, this is only possible if there is no protection against hacking, i.e. the absence of a freely rotating hardened washer, which protects against possible drilling of the code mechanism, as well as armor protection for the keyhole, which resists the rough blows of a sledgehammer, etc. etc. Unfortunately, only "native" Finnish castles meet all these requirements.

Cylinder systems are distinguished by the degree of secrecy. There are three types:

  • Low security - low secrecy: from 10 to 5000 combinations, and no security elements

    Middle security - medium secrecy: from 5,000 to 1,000,000 combinations, security elements may be missing

    High security - the highest secrecy: over 1,000,000 key combinations (usually 2-4 million), security elements are required.

  • Image

    A typical representative of the first group (Low security) can be seen in 80% of all doors in any entrance. Some models of such larvae can be opened in a few seconds with a hairpin or paper clip. These are cheap locks with low precision of the secret mechanism. Unfortunately, the overwhelming majority of domestic castles do not rise above this group. A distinctive feature of these cylinders can be considered the so-called "English key" and "cross key" (see figure)


    The second group (Middle security) on the domestic market is represented mainly by imported cylinders such as KALE (Turkey) and "SUPERLOCK" aka "YARDENY" or "GARD" (Israel) and the like. A distinctive feature is the so-called "key - punch card". The key has one or two rows of indentations of different sizes. Because of them, the key got its name.

    The third group is represented by the world leaders in the production of secret mechanisms. These are MUL-T-LOCK (Israel), ABLOY (Finland), VACHETTE (France), CISA and MOTTURA (Italy). The cylinder mechanisms of these companies cannot be opened with a master key, even the most sophisticated one - vibrating. Each of the leading firms has its own technology that allows you to bring the number of key combinations to several million. MUL-T-LOCK uses pin-in-pin technology - i.e. locking cylinders are telescopically positioned one in the other. The ABLOY system is fundamentally not unlike anything at all, and VACHETTE has locking cylinders at inconceivable angles across the entire area of ​​the key. The materials from which the cylinders of this group are made are acid and wear resistant. Victory rods and balls are hidden in all places of the cylinders seemingly accessible to the burglar,on which the drills break. MUL-T-LOCK, VACHETTE, CISA, and MOTTURA use key-to-punch card keys, and ABLOY uses Finnish keys.

    A huge number of key combinations allows you to make unique systems such as "MASTER KEY" (MUL-T-LOCK). In this system, each of several neighbors can use his own key to open the driveway, the door on his own floor and his own apartment, and at the same time also the lock on the gearbox of his car, and not a single key will fit someone else's door or car. MUL-T-LOCK also developed the INTERACTIV system, where an impression cannot be made from the key, and the SVETOFOR system is reprogrammed after using a new key.

    Domestic metal doors (with our own locks) mainly use a cylinder lock - locking - locking and lever - locking.

    In imported doors, as a rule, one lock is installed, locking - locking, but with additional security elements.

    And finally, a few tips:

    • equip your door with an alarm;

      don't skimp on good locks - it's more expensive for yourself;

      do not advertise your absences;

      do not let imaginary "locksmiths", "electricians" into the apartment;

      do not believe the "fire victims" who ask for alms.

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