Sliding blade features

A sliding knife is a knife which can be opened by sliding the knife blade out the front of the handle. One method of opening is where the blade exits out the front of the handle point-first and then is locked into place (an example of this is the gravity knife). Another form is an O-T-F (out-the-front) switchblade, which only requires the push of a button or spring to cause the blade to slide out of the handle, and lock into place. To retract the blade back into the handle, a release lever or button, usually the same control as to open, is pressed. A very common form of sliding knife is the sliding utility knife (commonly known as a stanley knife or boxcutter). A gravity knife is a knife with a blade contained in its handle, and which opens its blade by the force of inertia or gravity.[1] As the gravity knife requires gravity or spinning motion to propel the blade out of the handle, it differs fundamentally from the switchblade, which opens its spring-propelled blade automatically upon the push of a button, switch, or fulcrum lever.[1] The main purpose of this opening method is that it allows opening and closing to be done one handed, in situations where the other hand is occupied. A major historical use has been in issue to parachutists to cut off their parachutes when tangled in a tree or similar. The gravity knife uses a button, trigger, or fulcrum lever to release the blade from both the open and the closed positions, and may use a side-folding or telescoping (out-the-front, or OTF) blade. While most military gravity knives utilize a locking blade design, other types may not mechanically lock open but rely instead upon friction to wedge the rear section of the blade against the interior of the handle.[2] Factory-made g avity knives have various types of buttons, triggers, and fulcrum levers, which usually are used to release the blade from both the open and the closed positions. A utility knife is a knife used for general or utility purposes.[1] The utility knife was originally a fixed blade knife with a cutting edge suitable for general work such as cutting hides and cordage, scraping hides, butchering animals, cleaning fish, and other tasks. Today, the term "utility knife" also includes small folding or retractable-blade knives suited for use in the modern workplace or in the construction industry. The fixed-blade utility knife was developed some 500,000 years ago, when humans began to make knives made of stone.[1] These knives were general-purpose tools, designed for cutting and shaping wooden implements, scraping hides, preparing food, and for other utilitarian purposes.[1] By the 19th century the fixed-blade utility knife had evolved into a steel-bladed outdoors field knife capable of butchering game, cutting wood, and preparing campfires and meals. With the invention of the backspring, pocket-size utility knives were introduced[when?] with folding blades and other folding tools designed to increase the utility of the overall design. The folding pocketknife and utility tool is typified by the Camper or Boy Scout pocketknife, the U.S. folding utility knife, the Swiss Army Knife, and by multi-tools fitted with knife blades. The development of stronger locking blade mechanisms for folding knivesЧas with the Spanish navaja, the Opinel, and the Buck 110 Folding Hunter[citation needed]Чsignificantly increased the utility of such knives when employed for heavy-duty tasks such as preparing game or cutting through dense or tough materials.