Traditional Culture Encyclopedia - Traditional culture - What is the simplest way to unlock the old round-headed lock?

What is the simplest way to unlock the old round-headed lock?

The method is as follows:

Step 1: Find an ID card or a hard and thin plastic card, as shown below.

Step 2, slowly insert it from the gap between the door lock and the door crack, as shown in the figure below.

Step 3: Gently swing the handrail of the revolving door back and forth regularly, as shown in the figure below.

Step 4: Insert the card slowly and touch the "tongue" of the inverted lock, as shown below.

Step 5: Try to repeat. You can pull the "tongue" of the lock and the door can be opened, as shown in the figure below.