Automatic knives are a version of knife where the blade is concealed. Upon pushing a button, or something similar, the blade will quickly shoot out. In some states and countries, these knives are illegal.
Types and Pieces
Automatic switch blades come in many shapes and sizes, and because of this, the operating mechanism can slightly differ. However, usually the operating mechanism consists of a rectangular bar (which is connected to the button on the outside of the knife), and a spring that is connected to two L-shaped pieces of metal. Locking clips and springs work within a small space to exert pressure on the blade.
When you press the button on an automatic switchblade, the rectangular bar moves. This bar presses up against a locking clip. The locking clip has a small spring in it, so momentarily it holds the rectangular bar back. This puts tension on the larger spring, as it is connected to the L-shaped piece of metal, which in turn is pushing up against the blade. As the rectangular piece finishes pushing the locking clip out of the way, the tension that has been built up inside the spring from contracting against the locking clip fires the blade out of the handle via the L-shaped metal pieces. A second locking clip at the top, which constantly has pressure on it, slides under the blade once the blade reaches its zenith.
Automatic switchblade knives are illegal in some states. In the 1950s, popular movies portrayed shady characters brandishing automatic switchblades. Views and trends in pop-culture like this helped lead to the illegality of the knives in some states.