Pin Tumbler Lock, also known as marble lock, bead lock, spring lock or pin lock, Class A lock, is one of the most common lock structures. The principle is to use multiple cylindrical parts of different heights (called springs, pins or beads) to lock the lock core. When the correct key is inserted, each spring is pushed to the same height and the lock core is released.
To unlock a pin lock, you can first use a torque wrench to apply a torque force to the lock cylinder, and then use a pin-shaped lock pick to push the lock spring or pins up one by one until all are aligned with the cutoff point. Usually, the pins in the lock cylinder are not completely in a straight line. Under torque, only one of them is most likely to press against the lock cylinder. When this pin is pushed to the appropriate height, the lock cylinder will turn a little bit more until it is pinned by another pin. When the heights of all the pins are aligned, the torque wrench can open the lock. Sometimes the locksmith will first use the lock pick to quickly and forcefully pull outwards in the lock to push the pins upward; this may occasionally push some of the pins automatically to the appropriate height to reduce the time required to unlock the lock.
Some simple padlocks have only two to three pins, and the lock cylinder only needs to be turned 1/8 of a turn to open. Experienced locksmiths can open the lock without a torque wrench or lock pick, just a safety pin. However, some well-structured pin locks have various special devices inside, which make it difficult for the lock pick to push the pin to the correct height.
Another way to open a pin lock very quickly is to use a vibrating lock pick gun, or "bump keys" to push the pins. The principle of both tools is the same: insert the tool under the lower pin and bump it upward quickly at the same time. At this time, the lower pin will hit the pin, causing the upper pin to be thrown high in a very short time. As long as you grasp the instantaneous separation of the upper and lower pins, you can open the pin lock. This method allows people to open a large number of pin locks without technical training, and has attracted attention around the world. In order to prevent this unlocking method, some locks have another lock in the lock core, which must be pushed open with the appropriate pit on the key before it can be rotated.