The security door has used the B key silver that A key yellow is still useful? Can be thrown away

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The AB key of the anti-theft door can still be opened after the B key is used, which is not normal. >>>More

The marble room in the pit corresponding to the different depths of the A (decoration key) and B key has a special structure and is equipped with a 1mm steel ball between the upper and lower marbles. When the A key is used, the height of the lower marble in the marble chamber plus the height of the small steel ball is just flush with the lock cylinder, so the lock cylinder can be unlocked by twisting the lock cylinder with the A key; When using the B key, just the small steel ball can be pushed 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 open the lock cylinder (this principle is the same as the mother and son key system), but when the lock cylinder rotates at a certain angle, the small steel ball will be affected by the action of the spring spring, and fall into the blind hole that is cleverly designed on the lock cylinder in advance (this is the difference with the 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. >>>More

To be correct, it is the ABC key, 1 temporary key A for the contractor, 1 B key for destroying the temporary key function, and 5 C key for yourself. Of course, most of the security doors are only divided into AB keys, A keys for the contractor, and B keys that become invalid after using the A key. The principle is that the protrusion of the second key destroys the steel ball inside the door lock that the A key opens normally, so that the shape of the internal lock hole changes. >>>More

A, B, C key lock, it has A, B, C three keys.

The function of the A, B, and C keys is that when people install the lock, the owner can hand over the A key to the house decoration personnel for them to unlock the door in and out of the house, so the A key is also called the "decoration key"; The C key can also be used normally. When the decoration is completed, the owner does not need the decoration personnel to enter the room, the owner inserts the B key into the lock hole and turns the lock cylinder (circle), the A key loses the function of unlocking, and the key can be used normally in the future. >>>More

The owner uses the official key.

The bai key turns a du 360 degree circle outside the door, that is, after the zhi double insurance once, the decoration key dao key will be invalid. >>>More