How to use the AB key of the security door

The marble chamber in the pit corresponding to the different depths of the A and B keys has a special structure and is equipped with a 1mm steel ball between the upper and lower marbles. When using the A key, the height of the lower bullet in this marble chamber plus the height of the small steel ball is just flush with the lock cylinder, so the A key can be used to twist the lock cylinder to unlock; When using B key, just can be small steel ball ejected out of the lock cylinder, that is to say, the lower bead and the lock cylinder are flush at this time, so the B key can also be twisted to unlock the lock cylinder (this principle is the same as the child and mother key system), but when the lock cylinder rotates at a certain angle, the small steel ball will be subjected to the effect of the upper spring spring, fall into the blind hole that is cleverly designed on the lock cylinder in advance (this is the difference with the child and mother key system), some people call this small blind hole a trap, very appropriate. The diameter of this blind hole is larger than the small steel ball, but smaller than the diameter of the marble, otherwise the marble will fall and the lock cylinder will be stuck and cannot be unlocked.

Once the small steel ball falls into the blind hole, it can only rotate with the lock cylinder, will not run out of the blind hole, will not have an impact on the use of B key, but when using the A key, because there is no small steel ball, so the lower ball in this marble room can not be flush with the lock cylinder (the height of the difference small steel ball), it is not possible to unscrew the lock cylinder to unlock. 2. If the two keys A and B are compared and carefully observed, experienced people will find that one of the seven pits on the key is different (most people don't pay much attention to it and think that there is no difference between the two keys). Since the deepest pit at a certain position on the A key, the shallowest pit at this position on the B key (even flat, no pit), is generally the position of the 7th or 1st marble.

Speaking of which, I think people in the know must have an idea in their hearts, so Tongzhou District unlocks and reminds the majority of homeowners to take back the A key after it is used up, and properly store or destroy it. 3. In order to make it easy for people to distinguish, the manufacturer has 6 B keys encapsulated with a transparent hard shell, and 2 A keys are hung outside. There are also differences in the color of some A and B keys, 2 A keys are yellow, and 6 B keys are white.

6 B key encapsulated on the back of the instruction manual, the owner should read clearly before use, recognize the use of the two keys, do not get confused, to avoid the use of two kinds of keys.

The A key is the excessive key given to the workers during the decoration, the B key is used by themselves after the decoration, and the B key is invalid from this moment once the B key is clockwise (the normal direction of opening the door).

The manual says that it is clockwise or counterclockwise to rotate 360 degrees with the B key, and whether to use the A key to open the door first and then rotate 360 degrees with the B key or directly rotate 360 degrees with the B key.

The so-called A key and B key are a lock mode commonly used in home security doors today. Usually a security door has 2 A keys and 5 B keys. The A key, also known as the "worker's key", is used by workers during renovation.

At the end of the decoration, use the B key, that is, the "master key", to turn around in the lock, and the A key will automatically become invalid, and you can only use the B key to open the door.

A B If the key is used before and after the renovation, it is a good solution for customers to avoid replacing their own doors, and before the B key is used, the A key can open the outer door normally! Once the B key is inserted into the lock hole of the door lock, clockwise (in the normal direction of opening the door), the A key will be invalid from that moment on.