Kill switch
| Kill switch | |
|---|---|
 An unprotected kill switch |
|
| Classification | Mechanical component |
| Industry | Automotive, Energy, Engineering, Entertainment |
| Powered | No |
A kill switch, also known as an e-stop, is a security mechanism used to shut off a device in an emergency situation in which it cannot be shut down in the usual manner. Unlike a normal shut-down switch/procedure, which shuts down all systems in an orderly fashion and turns the machine off without damaging it, a kill switch is designed and configured to a) completely abort the operation at all costs and b) be operable in a manner that is quick, simple (so that even a panicking user with impaired executive function can operate it), and, usually, c) be obvious even to an untrained operator or a bystander. Many kill switches feature a removable barrier or other protection against accidental activation (e.g., a plastic cover that must be lifted or glass that must be broken).
Kill switches are featured especially often as part of mechanisms whose normal operation or foreseeable misuse may cause injury or death; designers who include such switches consider damage to or destruction of the mechanism to be an acceptable cost of preventing that injury or death.
Contents |
[edit] Physical world applications
A similar system, usually called a dead man's switch (for other names, see alternative names), as its name suggests, is a device intended to stop a machine in case the human operator becomes incapacitated, and is a form of fail-safe. They are commonly used in locomotives, tower cranes, freight elevators, lawn mowers, tractors, jet skis, outboard motors, snowblowers and snowmobiles.
[edit] Vehicles
If it is used to shut down vehicles and machinery if the operator loses control or is ejected, then it is called dead man's switch. A common example of this would be the kill switches used by boaters wherein a cord connects the kill switch to the operator (usually by their life jackets), and if the operator is thrown overboard in an accident, the cord will pull the switch and immediately shut down the vessel's engine. This prevents it from becoming a run-away vessel that could impose a danger to other vessels or swimmers at sea, and allows the operator to swim back to the vessel and re-board it.
NASCAR (National Association for Stock Car Auto Racing) requires all their stock cars to be equipped with a steering wheel-mounted kill switch, in case the accelerator pedal sticks and the driver needs to shut down the engine.
Kill switches are also used on land vehicles as an Anti-theft system and as an emergency power off. Such devices are often equipped into bait cars and set up so that observing police can trigger the switch remotely.
[edit] Machinery
A kill switch is also used for gasoline pumps or any other device that pumps large amounts of explosive or flammable chemicals. There is commonly a single kill switch for all pumps at a pumping station. The kill switch is also used on such things as industrial band saws and belt sanders. Kill switches are also found on school-use electric powered tools such as drills and wood/metal lathes.
[edit] Musical instruments
An electric musical instrument, such as a guitar or bass guitar, may have a kill switch, also known as a stutter switch. It is used infrequently but most commonly in heavy metal music. Contrary to popular belief, a kill switch doesn't break the circuit but works by switching between the hot signal from a pick-up and the ground signal. A typical way of achieving this is (on a guitar with a volume control for each pick-up) by turning down the volume on one of the pick-ups then alternating the pick-up selector switch between that pick-up and one with the volume turned all the way up. They are sometimes used when a singer doubles as a guitar player and isn't playing or sometimes used as an effect during a song. Tom Morello of Rage Against the Machine and Audioslave, Victor Smolski of Rage, Buckethead (for example, "Jordan" and "Circarama"), Ace Frehley of Kiss (such as in the intro to the song "Cold Gin" from the Kiss Alive! album and during his concert solos documented in numerous 1970s video bootlegs), and Jonny Greenwood of Radiohead are well known for their use of the kill switch. Jack White uses a kill switch during some of his performances and in songs like "Icky Thump". Greg Ginn of Black Flag achieved the notorious feedback scream which opens most of the tracks on Damaged with a kill switch. Kill switches are rarely a feature in production model instruments, although they are mainly an after-market modification and a feature on custom shop instruments. The kill switch circuit can also be built into an effects pedal and controlled by a foot switch.
[edit] Gym
Treadmills often use a safety key that the runner clips to his or her waist, and if they fall or trip, the safety key is pulled out, and the machine stops immediately. In other cases treadmills use a more traditional kill switch, often mounted towards the rear of one of the hand-railings.
[edit] Information technology
[edit] Computer software
The concept of "kill switch" may also be applied to software as an anti-piracy feature, most notably in Windows Vista. It renders the software essentially useless to users running what is determined by the software author to be an illegitimately obtained, or pirated, copy. In the example of Microsoft Windows, the company developed a verification tool named Windows Genuine Advantage, that originally activated a kill switch, or reduced functionality mode, on what Microsoft's mandatory software deemed to be an unlicensed copy of the operating system. Software kill switches have been shown to have varying degrees of success, as false positives have been known to occur,[1] prompting some vendors like Microsoft to "turn off" the software kill switch in response to market pressure.
There is some anecdotal evidence that some software vendors install kill switches in their software to enforce[2] planned obsolescence, also known as a forced upgrade. This can cause considerable disruption[3] in said customer's business functions.
[edit] See also
[edit] References
- ^ "'Kill switch' dropped from Vista". BBC News. 2007-12-04. http://news.bbc.co.uk/2/hi/technology/7126902.stm. Retrieved 2009-12-25.
- ^ "Another reason to love FOSS - Software Kill Switches". 2008-07-11. Archived from the original on 2008-07-13. http://web.archive.org/web/20080713182644/http://www.raiden.net/?cat=2&aid=438. Retrieved 2010-03-25.
- ^ "Why proprietary software is dangerous for business-critical applications". 2006-08-28. http://www.linux.com/articles/56449. Retrieved 2010-03-25.
