What Happens When the Key Is Turned?
All of that portion of the lock which is shown below the round central post is operated by the key. The square stud is attached to the bolt, and in figure 1, it is seen that the projections on the flat tumblers prevent the stud from moving forward, holding the bolt in retracted position. When the key is turned as shown in figure 2, it raises the tumblers releasing the stud, and then pushes the bolt out, the tumblers falling into position as shown in figure 3, with the projections again engaging the stud and preventing the bolt from moving until the key is turned backward, again raising the tumblers and releasing and retracting the bolt.