"Emergency stop" redirects here. For when trains make an emergency stop, see Emergency brake (train).
Kill switch
A kill switch without a cover
Classification
Mechanical component
Industry
Automotive, boating, energy, engineering, entertainment
Powered
Varies, some mechanical
A kill switch, also known more formally as an emergency brake, emergency stop (E-stop), emergency off (EMO), or emergency power off (EPO), is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner. Unlike a normal shut-down switch 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 a panicked operator with impaired executive 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. a plastic cover that must be lifted or glass that must be broken), known as a mollyguard. Kill switches are features of mechanisms whose normal operation or foreseeable misuse might cause injury or death; 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 a dead 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 of fail-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 and snowmobiles). 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.
Vehicles
An emergency switch in Japan
On railways,[1] an emergency stop is a full application of the brakes in order to bring a train 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 has passed a red signal or the driver has failed to respond to warnings to check that they are still alert, which is known as a dead man's switch. A similar mechanism is the watchdog timer.
In large ships, an emergency stop button pulls the countershaft for the fuel pumps to the stop position, cutting off the fuel supply and stopping the engines. With a controllable-pitch propeller, the stop button may declutch the engine from the propeller.
NASCAR 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.
A related concept is the dead 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 by boaters and jetskiers wherein a cord connects the kill switch to the operator (usually by the operator's life 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 the flywheel (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 their monster 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]
Pioneer-era planes and World War I aircraft
Early aviators using rotary engine–powered aircraft from the beginnings of their usein 1908, up through the end of World War I in 1918 had what could be called a reversed functionality version of the "dead man's switch" for cutting the ignition 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 called a "blip switch" or "coupe switch" (from the French term coupez, or "cut") and when not being pressed, allowed the high voltage from the engine's magnetos 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 conventional throttle in their carburettors to regulate engine speed, but only for governing the fuel-air ratio for start-up and full-speed operation.
Anti-theft
Kill switches are also used on land vehicles as an anti-theft system and as an emergency power off. Such devices are often placed in bait cars and configured so that observing police can trigger the switch remotely.[3] This same idea can make the stolen object, such as a smartphone, useless to both the thief and whoever buys it, yet allow the true owner to reactivate it when/if it is recovered.[4]
In smartphones, 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 in California for smartphones.[5] There are also hardware kill switches on some phones, such as PinePhone, where the user can, by moving a hardware switch inside the phone, disable hardware like the camera, microphone, Wi-Fi or LTE.[6]
See also Brick (electronics) – an electronic device that can no longer function due to software malfunction
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 of malware such as in the WannaCry ransomware attack.[9][10]
Google started to work on a hardware kill switch for AI in 2016.[13]
Industrial machinery
The arrows indicate that the stop button must be turned to reset the switch before the equipment can be restarted.
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] For fail-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 the European Union, most types of machinery are required to be equipped with an emergency stop according to the Directive 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 called SCRAM. It is usually characterized as an acronym for "safety control rod axe man", though this is probably a backronym.
Machine tools
Emergency stop functions are frequently used on machine tools, including equipment like wood and metal sawing machines, grinding machines, drilling machines, milling machines and machining centres and lathes. The emergency stop safety 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, the risk 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, like ANSI in the US, and CSA in Canada.[17][18]
Complementary protective measure
An emergency stop button with a custom-made plastic molly guard to prevent it from being pressed accidentally
A machinery's emergency stop control is considered a complementary protective measure[16] because it is intended to complement the primary safeguarding measures like fixed 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.
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]
Gym
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]
Amusement rides
The emergency stop on an amusement 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]
Military and other equipment
It is thought that some electronic chips used in equipment, particularly military, have a secret "kill" function that disables the equipment. It has been reported that French and Israeli electronic warfare units have used kill switches to disable opponents' military systems.[27] Systems have also been infected with malware specifically designed to damage them.[28]
John Deere tractors have been criticised for it being impossible for owners to service or repair them; only John Deere has access to computer code required for this and to accept non–John Deere replacement parts. Vital equipment from other manufacturers such as critical medical equipment has similar restrictions. Remote locking by the manufacturer may also be possible.[29] It was reported that during the 2022 Russian invasion of Ukraine Russian troops stole Ukrainian farm equipment, but that the dealers who owned the equipment locked it remotely.[30]
Safety engineering is an engineering discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety engineering. Safety engineering assures that a life-critical system behaves as needed, even when components fail.
In engineering, a fail-safe is a design feature or practice that, in the event of a failure of the design feature, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent safety to a particular hazard, a system being "fail-safe" does not mean that failure is naturally inconsequential, but rather that the system's design prevents or mitigates unsafe consequences of the system's failure. If and when a "fail-safe" system fails, it remains at least as safe as it was before the failure. Since many types of failure are possible, failure mode and effects analysis is used to examine failure situations and recommend safety design and procedures.
A railway air brake is a railway brake power braking system with compressed air as the operating medium. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on April 13, 1869. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell Westinghouse's invention. In various forms, it has been nearly universally adopted.
A safety-critical system or life-critical system is a system whose failure or malfunction may result in one of the following outcomes:
A dead man's switch is a switch that is designed to be activated or deactivated if the human operator becomes incapacitated, such as through death, loss of consciousness, or being bodily removed from control. Originally applied to switches on a vehicle or machine, it has since come to be used to describe other intangible uses, as in computer software.
A vehicle start-stop system or stop-start system automatically shuts down and restarts the internal combustion engine to reduce the amount of time the engine spends idling, thereby reducing fuel consumption and emissions. This is most advantageous for vehicles that spend significant amounts of time waiting at traffic lights or frequently come to a stop in traffic jams. Start-stop technology may become more common with more stringent government fuel economy and emissions regulations. This feature is present in hybrid electric vehicles, but has also appeared in vehicles that lack a hybrid electric powertrain. For non-electric vehicles, fuel economy gains from this technology are typically in the range of 3–10%, potentially as high as 12%. In the United States, according to the Department of Energy, idling wastes more than 6 billion U.S. gallons of fuel per year.
Elisha Graves Otis was an American industrialist and founder of the Otis Elevator Company. In 1853, he invented a safety device that prevents elevators from falling if the hoisting cable fails. On March 23, 1857, he installed the first safety elevator for passenger service in the store of E.V. Haughwout & Co. in New York City.
On trains, the expression emergency brake has several meanings:
An aerial work platform (AWP), also known as an aerial device, elevating work platform (EWP), aerial lift, cherry picker, bucket truck or mobile elevating work platform (MEWP) is a mechanical device used to provide temporary access for people or equipment to inaccessible areas, usually at height. There are distinct types of mechanized access platforms and the individual types may also be known as a "cherry picker", "boom lift" or "scissor lift".
A built-in self-test (BIST) or built-in test (BIT) is a mechanism that permits a machine to test itself. Engineers design BISTs to meet requirements such as:
A push-button or simply button is a simple switch mechanism to control some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased switches, although many un-biased buttons still require a spring to return to their un-pushed state.
Chainsaws and chainsaw operations have specific risk control methods.
A motor vehicle has lighting and signaling devices mounted to or integrated into its front, rear, sides, and, in some cases, top. Various devices have the dual function of illuminating the road ahead for the driver, and making the vehicle visible to others, with indications to them of turning, slowing or stopping, etc., with lights also indicating the size of some large vehicles.
A panic alarm is an electronic device that can easily be activated to request help during an emergency where danger to persons or property exists. It is designed to contact assistance quicker, easier, and simpler than a conventional phone call.
A Shopping Cart Conveyor also known as Vermaport, Cartveyor or shopping cart escalator is a device used in multi-level retail stores for moving shopping carts parallel and adjacent to an escalator. Shoppers can load their shopping carts onto the conveyor, step onto the escalator, ride the escalator with the cart beside them and collect the cart with the contained merchandise at the next level.
An elevator or lift is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems such as a hoist, although some pump hydraulic fluid to raise a cylindrical piston like a jack.
Sifa is a type of deadman's control system used on German-influenced European railways. Although deadman's pedals are commonly used on railways worldwide, Sifa systems are specifically those codified by German Industrial Norms VDE 0119-207-5.
Safety relays are devices that generally implement safety functions.
A presence sensing device (PSD) is a safety device for press brakes and similar metal-bending machines. The device operator often holds the sheet metal work-piece in one place while another portion of the piece is being formed in the die. If a foreign object is detected, the PSD immediately retracts the die or stops the motion of the ram. PSDs protect the operator and other employees in the area.
ISO 7010 is an International Organization for Standardization technical standard for graphical hazard symbols on hazard and safety signs, including those indicating emergency exits. It uses colours and principles set out in ISO 3864 for these symbols, and is intended to provide "safety information that relies as little as possible on the use of words to achieve understanding."
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
