| Kill switch | |
|---|---|
 A kill switch without a cover | |
| Classification | Mechanical component |
| Industry | Automotive, boating, energy, engineering, entertainment |
| Powered | Varies, some mechanical |
Akill switch, also known more formally as anemergency brake,emergency stop (E-stop),emergency off (EMO), oremergency power off (EPO), is asafety mechanism used to shut offmachinery in anemergency, when it cannot be shut down in the usual manner. Unlike a normal shut-downswitch or shut-down procedure, which shuts down all systems in order and turns off the machine without damage, a kill switch is designed and configured to abort the operation as quickly as possible (even if it damages the equipment) and to be operated simply and quickly (so that even apanicked operator with impairedexecutive functions or a bystander can activate it). Kill switches are usually designed to be noticeable, even to an untrained operator or a bystander.
Some kill switches feature a removable, protective barrier against accidental activation (e.g. aplastic cover that must be lifted orglass that must be broken), known as amolly-guard. Kill switches are features of mechanisms whose normal operation or foreseeable misuse might causeinjury ordeath; industrial designers include kill switches because damage to or the destruction of the machinery is less important than preventing workplace injuries and deaths.
A similar system, usually called adead man's switch, is a device intended to stop a machine (or activate one) if the human operator becomes incapacitated or leaves the machine unattended, and is a form offail-safe. They are commonly used in industrial applications (e.g.,locomotives,tower cranes,freight elevators) and consumer applications (e.g.,lawn mowers,tractors,personal watercraft,outboard motors,snow blowers,motorcycles andsnowmobiles). The switch in these cases is held by the user, and turns off the machine if they let go. Some riding lawnmowers have a kill switch in the seat which stops the engine and blade if the operator's weight is no longer on the seat.
Onrailways,[1] an emergency stop is a full application of thebrakes in order to bring atrain to a stop as quickly as possible.[2] This occurs either by a manual emergency stop activation, such as a button being pushed on the train to start the emergency stop, or on some trains automatically, when the train haspassed a red signal or the driver has failed to respond to warnings to check that they are still alert, which is known as adead man's switch. A similar mechanism is thewatchdog timer.
In largeships, an emergency stop button pulls thecountershaft for thefuel pumps to the stop position, cutting off the fuel supply and stopping the engines. With acontrollable-pitch propeller, the stop button may declutch the engine from the propeller.
NASCAR requires all their stock cars to be equipped with asteering wheel–mounted kill switch, in case theaccelerator pedal sticks and the driver needs to shut down the engine.
A related concept is thedead man's switch, where the operator must be holding a button or lever any time the vehicle is operating. A common example of this is the kill switches used byboaters andjetskiers wherein a cord connects the kill switch to the operator (usually by the operator'slife jacket or clothing), 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 runaway 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 without the risk of being injured by the boat's propeller. A similar device is featured on most lawnmowers: a lever on the handle either disables the ignition system and applies a brake to theflywheel (on a gasoline lawnmower), or cuts the power to the motor (on an electric lawnmower), as long as it is not held down.
Monster Truck Racing Association requires all of theirmonster trucks to be equipped with kill switches (either remote or in cab), in case the monster truck loses control and the driver needs to shut off the engine. Monster trucks' kill switches are tested before races.[citation needed]
Early aviators usingrotary engine–powered aircraft fromthe beginnings of their usein 1908, up through the end ofWorld War I in 1918 had what could be called a reversed functionality version of the "dead man's switch" for cutting theignition voltage to the spark plugs on such a power-plant, to give a degree of in-flight speed control for a rotary engine. This was often calleda "blip switch" or "coupe switch" (from the French termcoupez, or "cut") and when not being pressed, allowed the high voltage from the engine'smagnetos to operate the ignition with normal engine operation in flight—pressing the "blip switch" cut the flow of high voltage from the magnetos, stopping the combustion process in the cylinders. When such a "blip switch" was intermittently used on landing approach, this allowed a limited degree of engine speed control, as rotary engines generally did not have a conventionalthrottle in theircarburettors to regulate engine speed, but only for governing the fuel-air ratio for start-up and full-speed operation.
Kill switches are also used on land vehicles as ananti-theft system and as an emergency power off. Such devices are often placed inbait cars and configured so that observing police can trigger the switch remotely.[3] This same idea can make the stolen object, such as asmartphone, useless to both the thief and whoever buys it, yet allow the true owner to reactivate it when/if it is recovered.[4]
Insmartphones, a kill switch is a security feature that allows the phone's owner to remotely render the smartphone inoperable if it is lost or stolen. From 2015 this feature is legally required inCalifornia for smartphones.[5] There are alsohardware kill switches on some phones, such asPinePhone, where the user can, by moving a hardware switch inside the phone, disable hardware like the camera, microphone, Wi-Fi or LTE.[6]
By analogy to physical kill switches,kill switch can be used to refer to a mechanism incorporated in software that can be activated by its manufacturer or licensor, for example if the product is withdrawn, or a maintenance fee has not been paid, or a device has been lost or stolen.[7][8] It can also refer to kill switches for the stopping ofmalware such as in theWannaCry ransomware attack.[9][10]
There is a debate about implementing kill switches inrobots[11] and advancedartificial intelligence systems.[12]
Google started to work on a hardware kill switch forAI in 2016.[13]
On large industrial machines, an emergency stop button is typically located on the panel, and possibly in several other areas of the machine. Often, an emergency stop is made wireless using a remote control. This provides a rapid means to disconnect the energy source of the device to protect workers.[14] Forfail-safe operation, the emergency stop button is a normally closed switch, which ensures that a broken wire will not prevent it from being activated, but may accidentally activate the emergency stop.
In theEuropean Union, most types of machinery are required to be equipped with an emergency stop according to theDirective 2006/42/EC. Exceptions apply for machinery in which an emergency stop would not lessen the risk as well as for portable hand-held/hand-guided machinery.
A kill switch in a nuclear reactor plant is calledSCRAM. It is usually characterized as an acronym for "safety control rod axe man", though this is probably abackronym.
Early computers were large electrical devices and typically had an emergency off switch located on or near the operator's console.
Emergency stop functions are frequently used onmachine tools, including equipment like wood and metalsawing machines,grinding machines,drilling machines,milling machines and machining centres andlathes. The emergency stopsafety function, and general requirements for emergency stop devices are set out in ISO 13850.[15] Machine specific (type-C) standards often include specific requirements for the emergency stop functions, but in the absence of a relevant type-C standard, therisk assessment should be used to determine whether or not an emergency stop function would be useful in avoiding or limiting harm. The ISO machinery safety standard types are defined in ISO 12100,[16] and this nomenclature is used by other standards development organizations, likeANSI in the US, andCSA in Canada.[17][18]
A machinery's emergency stop control is considered a complementary protective measure[16] because it is intended to complement the primary safeguarding measures likefixed guards, movable interlocked guards or safeguarding devices. The primary safeguarding measures prevent injury automatically, either by enforcing distance between a hazard and a person, or by eliminating the hazard by stopping hazardous motion or switching off a source of hazardous energy.
By contrast, an emergency stop requires a deliberate action on the part of a person who must first recognize that some hazardous condition is about to arise or is arising, and who then must activate the emergency stop function by pressing the emergency stop button or activating another emergency stop device such as a pull-cord switch.
A kill switch is also used forgasoline pumps or any other device that pumps large amounts ofexplosive orflammablechemicals. There is commonly a single kill switch for all pumps at apumping station.
Elevators[19][20] often have a red two-way button on the control panel which is either marked "Emergency Stop" or "Run/Stop". Normally, the button is in the "up" or unpushed position, allowing the elevator to "run" in normal service. When the button is pushed, the elevator comes to an immediate stop. When the button is pulled back out, it resumes normal service, thus the reason for the use of the phrase "Run/Stop".Escalators will typically have a key-operated control that will turn the escalator off, or change its direction to up or down. Next to the key switch will be a red "Emergency Stop" button, which is used in the event of equipment failure, or where there is a potential for injury, such as when someone's shoe gets stuck in the "comb" at the top or bottom of the escalator and there is a risk of serious injury. The key switch is used to return the escalator to service after it has been stopped.[21][22]
Treadmills[23] often use a safety key with one end magnetically attached to the machine and the other end clipped to the user's waist. If the safety key is pulled out, such as in the event of a fall, the treadmill stops immediately. In other cases, some other treadmills have a more traditional kill switch, often mounted towards the rear of one of the hand railings.[24][25]
The emergency stop on anamusement ride is similar to that on industrial equipment. Typically brakes on a ride are designed to be disengaged when power is applied; disconnecting power will cause all brakes to engage. Most amusement rides have a computer that can, similar to the rail example provided above, engage the emergency stop when such a ride is determined to be out of operating specification, or an accident involving a passenger or ride employee has happened.[26]
Range safety systems can automatically destroy errant vehicles in-flight. Range-safety officers may also manually destroy vehicles; this method was used to destroy errantsolid rocket boosters in theSpace ShuttleChallenger disaster.
intercom .. emergency alarm button .. emergency stop switch
emergency shut-off switches on escalators.
The emergency stop switch is a safety device used in emergency situations to stop the treadmill
Media related toEmergency stop buttons at Wikimedia Commons
