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. Gym Treadmills 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. 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. 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. And systems have been infected with malware specifically designed to damage them. 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. It was reported that during the 2022 Russian invasion of Ukraine Russian troops stole