If once all the doors were wooden, today most of the entrance doors to apartments and porches, not to mention the gates of country houses, are made of metal. And not always their design allows the use of mortise locking devices, in such cases, an invoice lock is installed.
Benefits of overhead locks
A padlock for a metal door has several advantages that can shift the scales to its side when choosing:
- When installing an installation that does not require special skills and a complex tool, that is, you do not always need to call a locksmith, and the owner can easily install the lock himself.
- For installation, it is not necessary to open the frame, and in many cases the door leaf, while preserving its protective functions as much as possible.
- Repair of locks that do not need to be removed from the cavity of a metal box is easier to carry out, as well as their replacement.
- The full thickness of the door locking device is protected from rough mechanical breaking. At least, it will not be possible to silently remove the lock or violate its integrity.
In addition, the flat sheet design of the door (into the staircase, for example) can dictate its installation conditions for the lock.
Disadvantages of overhead locks
But, unfortunately, the ease of installation also turns out to be the ease of unlocking the lock from the inside of the apartment without a key, if, say, robbers managed to get into it through a window. And besides, the overhead lock for a metal door cannot be upgraded and exchanged for another design.
With the help of a pry bar or a hammer, such a locking device is easy to open, if not afraid of noise.
Whatever their design, the appearance of the inside of the door with overhead locks is much less aesthetic (and dust has to be cleaned) than a smooth canvas.
Mounting a padlock
The door bill lock, regardless of the model and design features, is installed on the inside of the door so that it completely protrudes above the door leaf (overlays). To fix the case, a special strip is used, welded or bolted to the door.
If there is none in the plank or in the door leaf, the holes for the fasteners of the locking mechanism and the counterpart, as well as for the key, are marked. Then these holes are carefully drilled.
The laid-on lock of the simplest design is screwed onto the door leaf from the inside with screws and the strip of its inlet is set outside. That's the whole installation of the padlock.
True, these are the main stages. And additional actions, such as installing handles or a cylinder, depend on the design features of the locking device.
Classification of overhead locks
Overhead locks are classified according to several criteria. And perhaps the most important of them is the degree of security of the castle.
According to the design features, locks can be crossbar or bezelless, designed for left-side or right-side doors. Now you can choose a suitable patch lock for a metal door without turning it upside down and then opening it in the opposite direction.
Locks can be double-sided, opening with a key from the outside and inside, or one-sided, which can be opened with a key only from the outside. They may have additional functions, such as, for example, a latch lock with a latch, fixed or spring.
Overhead locks are made of different materials, which affects not only the cost, but also the reliability and durability of the device.
Materials for the manufacture of locks
When choosing locks, you must pay attention to what material they are made of. So, plastic is generally not suitable for heavy metal doors. Soft silumin or brass, brittle cast iron, although it is stronger than non-ferrous alloys, are also not a good choice.
At the door to the porch, which should serve as protection and in severe frosts, the shockproof cast-iron lock in the winter becomes fragile and can be destroyed by minor mechanical influences.
High-strength steels withstand both temperature extremes and shock, and locks from them are characterized by high anti-burglary qualities.
Classification of padlocks by type of locking mechanism
By the type of locking mechanism, three types of locks are distinguished, including overhead locks:
- Cylinder. In addition to simplicity and reliability, a major advantage is the easy repair of locks by replacing the larva (cylinder mechanism). The degree of protection of the castle depends on its complexity.
- Level locks. They are considered the most reliable. Sledgehammers are called curly plates located inside the castle. The more of them, the more reliable the castle. But the warty keys with which the plates move are large enough, as, indeed, the locks themselves. Judging by the reviews, not everyone likes these bulky mechanisms from the inside of the door. Another drawback of lever locks is that they can only be opened with a key from the inside.
- Smartlocks. No keys are needed for these modern mechanisms. They open with a code, like many doors to an entrance. But abrasion of buttons from frequent pressing leads to the fact that the code ceases to be a secret, and it has to be changed often.
Smartlocks, by the way, can be opened using a pattern of the retina or fingerprint. Most likely, such locks for safes are suitable - and only personal ones, but they are very expensive.
Classification by mode of action
According to the method of operation, overhead locks can be divided into mechanical, which are most common today and are opened with keys, and electrical devices.
Electromechanical devices are the same code smartlocks. Such a door bill lock consists of a bolt mechanism and a dashboard on which a programmed code is dialed. Its significant drawback is the dependence on the availability of electricity. It is necessary to turn it off, and the lock stops working, and the door remains open.
The same drawback is inherent in electromagnetic locks, which are universally installed on the porch door in multi-storey residential buildings. The locking mechanism is tuned to the electromagnetic fields of the keys and opens as soon as the magnetic key is brought to the reader on the external panel.
It’s almost impossible to break these locks without preparation; expensive code is needed to select the code.
Expensive electromechanical or magnetic locks can operate from a battery installed on the inside of the door. And then their main drawback is eliminated.
Lock Security Classes
There are four classes of security locks. They are determined not only by mechanical strength, which does not allow elementary knocking out of the lock. By the way, many negative reviews about overhead locks are based on the experience of distant and not very childhood, when it was possible, having stretched a little, to knock out overhead locks on wooden doors that open inwards. Modern metal doors open outwards, and it is almost impossible to knock such a structure out of a metal frame.
Another parameter that affects the security class is the degree of security of the lock, that is, the ability to pick a master key:
- First-class security locks open in minutes. This is an English (or cruciform) castle.
- The second class includes locking mechanisms that can be opened in about 10 minutes, both silently and with the help of a power tool, which undoubtedly attracts attention. If the security class is not specified in the accompanying document, then the mark that the lock is suitable for interior and exterior doors already speaks of this.
- Judging by the numerous reviews, the most requested locking device is an overhead lock for a third-class metal door. Opening time of such a lock is from 15 to 30 minutes, and it does not do without noise. Many models have additional protective pads. Level locks belong to this class of safety.
- Locking mechanisms of the fourth class can resist hacking from half an hour to three hours, depending on the degree of complexity of the lock and additional locks. They are used, for example, in safes and doors of rooms to which increased requirements for protection are imposed.
Secrecy of a padlock
The security of the lock includes security (protection against mechanical impact and hacking with a master key), the number of key and lock combinations, the device's durability and the likelihood of keys matching.
There are three levels of secrecy. The simplest locks made of low-strength materials with the number of possible combinations of up to 10 thousand belong to a low level of secrecy.
Average secrecy is already from 5 thousand to 5 million combinations. In such devices, the locking mechanism is made of high quality materials, and manufacturers save on materials of the case and handles.
Locks for safes have the highest level of secrecy. They are protected from mechanical impact and breaking, the materials are even resistant to acid, the key profile is very complex, there are up to a billion possible combinations of keys and locks, and the manufacturing accuracy of parts is high.
Safe overhead locks
Locks for safes and valuables can be called the top of overhead locks for metal doors. They can be locked with a key and using a mechanical or electronic combination, with magnetic or biometric identification.
Mechanical locks are most often lever locks; two grooves have keys to them. Less common are cylindrical or pump-action locks with diagonal notches on the crossbar, matching the key notches. When you press the key of its notches, the crossbars are disengaged from the counterpart. Complex geometry allows you to open the lock only when the notches are absolutely coincident.
Electronic locks allow you to complicate the keys and increase the number of operations or tie the work with the safe to a specific artist with certain biometric indicators, fingerprints, for example.
Popular models of padlocks
Overhead locks are a lot of cheap, but saving on price leads to a primitive and quick hacking and a negative attitude towards overhead locking devices in general.
According to reviews, the most popular in terms of price and quality are the locks of the Polish company GERDA. This company pays attention to the aesthetic function of its padlocks. They are available not only in various colors, but also in several styles.
The overhead cylinder lock of the Gerda ZN 100 and ZN 200 models is designed for entrance and internal doors, but has a sufficient degree of secrecy, reliable operation and is equipped with anti-slip ergonomic rotary handles.
High-quality lever locks are produced by the Russian-Italian company CISA - Elbor. For example, Elbor Sapphire 1.09.56.MA with the fourth safety class, 12 levers and the number of combinations in excess of 10 million.
Castle bill "Dori-4 classic" - the most famous product of the Sevastopol company DORI. It has no analogues in the world. Despite the fact that it is coded, the lock withstands shocks of up to 500 kg and has two dozen useful functions.
Overhead locks for metal doors are numerous. They are produced by well-known manufacturers who seriously care about their own reputation, and therefore about high quality products. When choosing a lock, you need to carefully study the accompanying documentation and check the quality of the mechanism. For example, clicks and mashing indicate that the parts are poorly adjusted and can lead to problems during operation.