1. Multi-dial combination lock
The simplest combination lock, commonly found in bicycle locks with low security settings, uses multiple dial rings. There is a recess in the middle of each circle. There are several protruding teeth on a shaft in the center of the lock to hold the dial ring. When the dial ring turns to the correct combination, the lock can be opened. This kind of lock is the easiest to open. Many of these locks can be opened without knowing the password. Unless its internal components are made flawlessly, as long as the shaft is pulled out, one of the teeth will tighten the dial ring more tightly than the others. At this time, turn the tightened dial ring until a small "click" sound is heard, indicating that the tooth has entered the correct recess. Repeat this step and the lock can be opened soon.
2. Rotating disc type combination lock
The rotating disc type combination lock can have only one dial. The dial pushes several balance discs or cams on the back. It is customary to turn the dial clockwise to the first number when opening this lock, and then to the second number counterclockwise, and so on to the last number. There are usually recesses on the cam. When the correct combination is entered, the positions are aligned and the lock can be opened.
These lock kinds are more secure, but their are not without their shortcomings. For example, for some password padlocks, the lock head can be tightened. And then turn the dial until it can no longer move, so that the password can be found. There is also a specific relationship between the numbers of some rotating disc type combination locks, which greatly reduces the possibility of the combination of passwords. Inexpensive combination padlocks can be opened with special linings without the use of passwords. The combination lock used on the box has a strict structure. An experienced locksmith can rotate the dial while using the earpiece to carefully listen to the sound of the cam inside the lock to determine the possible combination.
3. Mechanical combination lock
Mechanical combination locks are relatively stable, durable, and do not require power supply. However, it is relatively slow to learn the operation method because the operation is inconvenient, and professionals are required to change the password.
4. Electronic combination lock
The electronic combination lock has the advantages of fast operation, simple modification of the combination, and the lock can be unlocked only by inputting numbers of 0 to 9. Although the price of electronic combination locks has dropped in recent years and the quality has improved, it is not as stable and durable as mechanical combination locks because of its complexity.
5. Card-swiping combination lock
The card-swiping combination lock enables you to use your own IC card to open the safe door. The operation is simple, but the requirements for the IC card are relatively high. If it comes in contact with a strong magnetic object, the magnetism of IC card may be weakened and therefore it cannot open the combination lock.
6. Fingerprint combination lock
It is difficult to find the same fingerprint in this world, so fingerprint recognition technology is applied to the safe, which is highly confidential and easy to use. And it's usually designed as knob lock. However, the requirements on humidity are strict! The position of the finger that can be recognized is also relatively restricted! As to this kind of fingerprint door knob lock, even if it is the same finger, if the position before inputting the fingerprint is different from that before opening the door, the recognition may fail!
7. Other types of the combination lock
Some door locks have a numeric keypad, and it is required to type a series of numbers in sequence when opening. This type of lock is electronically controlled and is commonly found in office rooms. The advantage is that as long as the employee is told the password, there is no need to copy the key. However, if someone tells an outsider the password, the lock becomes useless. Therefore, the password of this type of combination lock needs to be changed frequently. This kind of lock has a 3 to 6 digit password, which is extremely confidential.