Combination lock information. About the combination mechanism, combination door locks, padlocks, picking. Also places where you can buy combination lock.

Combination Cable Lock (Click to enlarge)

Is a type of lock in which a sequence of numbers or symbols is used to open the lock. The sequence is usually a specific permutation rather than a true combination. The sequence may be entered using a single rotating dial which interacts with several discs or cams, or by using a set of several rotating discs with inscribed numerals which directly interact with the locking mechanism. One of the simplest types of combination lock, often seen in low-security bicycle locks, uses several rotating discs with notches cut into them. The lock is secured by a pin with several teeth on it which hook into the rotating discs. When the notches in the discs align with the teeth on the pin, a combination lock can be opened.

Combination Door Lock:

Many doors use locks which require the user to enter a numeric sequence on a keypad to facilitate entry. These combination locks usually require the additional use of electronic circuitry. The chief advantage of this system is that if used for the door of a large office, each employee can be told the code number without having to supply a key to each person. However, if the code number is learnt by someone outside the desired group or is not changed regularly, it could allow easy access to a potential intruder.

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Combination Padlocks and Cable Locks:

Combination locks found on padlocks or safes may use a single dial which interacts with several parallel discs or cams. Customarily, a lock of this type is opened by rotating the dial clockwise to the first numeral, counterclockwise to the second, and so on in an alternating fashion until the last numeral is reached; the cams typically have an indentation or notch, and when the correct combination is entered, the notches align, allowing the latch to fit into them and open the lock. Also as padlocks, there are Combination Cable Locks, for the same purpose of padlock but having a large cable.

Price Range: US$3.99 - US$23.08 / £2.12 - £12.26

Combination Lock from Master Lock (Click to enlarge)

Combination locks are one of the best secure systems. But many locks of this type can be opened without knowledge of the correct combination. Opening a combination lock depends on slight irregularities in the machining of the parts. Unless the lock is machined precisely, when the pin is pulled outward, one of the teeth will pull more strongly than the others on its corresponding disc. This disc is then rotated until a slight click is heard, indicating that the tooth has settled into the notch. The procedure is repeated for the remaining discs, resulting in an open lock, and a correct combination, in very little time.