Combination Locks
Combination locks are locks that open only when their dial is turned to a predetermined position or sequence of positions on its dial face. These positions may be numbers or letters. Combination locks are not opened by a key but rather by the alignment of its interior parts in a specific position. When all of the rings inside the lock align, they allow a spring-loaded bolt to slide through, which releases the bolt and opens the lock. Simply closing the lock and moving the dial to a different position resets the lock.
In the past, the reliability of combination locks was questioned due to the seemingly relative ease of picking locks. More recently, however, better manufacturers of combination locks design false gates in the discs, which makes picking the lock extremely difficult. In fact, a lock with four discs can use any of 100,000,000 possible combinations, so guessing the correct combination is highly unlikely.
Two primary types of combination locks exist: hand and key change. Pushbutton lock, common hand combination locks, are frequently installed in office doors for security. In these locks, pushing three or four buttons in sequence or altogether releases a deadbolt that opens the door.
Combination locks are constructed to last a lifetime, and their parts are not intended to require repair or replacement. Typically constructed of steel, combination locks are also often coated to resist corrosion. Combination locks retain a reputation for durability and reliability and are utilized in a wide range of applications.