Each lock has its own differences in construction, which determines its different functions. As for the principle of unlocking, the principle of unlocking is the same for most locks, except for some locks such as magnetic card lock and electronic lock. General locks, such as ordinary door locks, pull lock locks, cross door locks, etc., although their styles and structures are different, but the principle of unlocking is exactly the same. As the saying goes: 'there is no change without it! 'The reason why these locks and unlocks are the same is that their lock centers are all round objects. People who have studied physics know that only circular objects can rotate freely. The square flat shape means that the object can't be turned at will. It's also a better way to unlock the lock. Its unlocking principle is the same as that of using a paddle, but it needs to grasp more than just using hands. Some locks with I-shaped bullets are easier to unlock. The way to unlock is to extend the gun needle installed in front of the unlocking gun into the key hole. Before extending it, you must Push the push rod well to form a dislocation, but the pushing force must not be too strong. First, start to buckle the board machine from the outside, then one bullet and one bullet. If not, then the bullet from the inside to the outside. The bullet can make the upper and lower bullets separate to achieve the purpose of unlocking. It is applicable to the lock with large key hole ratio, such as the cross lock of the common billiard door and the common car lock.