The cylinder lock
Modern locking systems are works of art of precision engineering, but even they do not offer absolute security.
Locking technology, that's how the technical jargon soberly describes a competition: With a mix of modern materials technology, physics and mathematics, manufacturers of security systems such as cylinder locks make life difficult for thieves and burglars. Even if every lock can ultimately be cracked, the effort required should deter criminals. The basic principle of mechanical locks is simple and was already known in ancient times. A spring mechanism presses a bolt firmly into a recess in the door frame, a key can push this bolt back. So that a thief is not satisfied with a simple hook as a lockpick, locking pins block the bolt. They are lifted by the pro of the key bit and thus clear the way. This principle was already known to the Romans.
Simple systems like this are only suitable for living room cupboards or garden sheds. From bicycle locks to company locking systems, the cylinder lock is the security standard. The key moves a roller in a tube, also turning a metal lug that runs in a groove in the tube. This, in turn, engages in a mechanism that ultimately pulls back the door bolt(s). They consist of the actual pin and a bolt fitted with a spring. If the right key is inserted, its profile lifts or presses these elements in such a way that all the pins are in one line and disappear into the cylinder - it can now be rotated.
Top products such as those from the German manufacturer Winkhaus not only have vertical but also cross-action fuses that are moved via indentations in the side surfaces of the key. There are even magnetic systems on the market: Tiny magnets in the key pull or repel bolts.
A simple beard already has five positions for the notches, each of which can have about eight possible depths. That already gives 32,768 possible profiles. The we alth of combinations results in hierarchies, as required by locking systems. For example, for an apartment building: Every resident can use their key to open the front door and general basement rooms, but beyond that only their own apartment. Or the hierarchy for a school complex: the caretaker must be able to enter all rooms, a physical education teacher next to the staff room and his classrooms the corresponding exercise facilities, etc. The more complex a system is, the more combinations are available: the risk of similar keys becoming very small. The security card belonging to the respective locking system protects against unauthorized copying: only its owner receives a duplicate key.
But how do burglars always manage to reach their target? And how can locksmiths help people who have locked themselves out? If the door was not locked at all, a simple check card is sufficient. Pushed against the slope of the bolt between the door and the door leaf, she pushes it back. Burglars also use this trick to break into houses, the "credit card" is then a metal plate. In any case, it's worth really locking the door when you leave a sensitive area. Experienced people can also open middle-class locks in a few minutes. They apply torque to the cylinder via a clip. It would rotate in the lock were it not for the extended locking pins. These are then successively palpated with fine instruments and snap back. The cylinder can now be rotated exactly once. However, special safety latches cannot be outwitted in this way. They react sensitively: Because they are not properly positioned by the key, they slide along the roller, so to speak, which moves due to the torque. The safety latches cant and block the lock against further improper movement.
Some burglars don't even try to open a lock. Simple products can be pulled out, drilled out or cut out completely. Once the cylinder has been removed, the door bolt can easily be pulled out of the door leaf with pliers. Security door hardware helps against pulling. Very good locks are also made of hard alloys, have a core made of special steel and possibly other reinforced areas. A special bolt anchors the cylinder in the door.
But even the best cylinder lock does not provide security if it is easy to circumvent. Therefore, the door must also be secured on the wall side - by installing a special security door leaf that is screwed firmly into the wall.
Did you know?
- Safe locks have several bolts, an invention dating back to 1818. Lamellae arranged one behind the other are lifted into the correct position by the steps in the key bit in order to free up a channel for the bolt set the correct number and a bolt will drop to a different position, unlocking the door.
- Today's cylinder locks are often modular, i.e. they consist of individual cylinder elements that can be combined.
- Locking systems in companies and security-related facilities often replace mechanical keys with chip cards. This enables additional functions such as recording working hours or controlling the light and heating. Radio and infrared keys that send an encrypted code have been developed to prevent car theft.
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