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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 ...
A push-button (also spelled pushbutton) 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. [1] The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed.
The standard type consists of two circular indicator lamps and a square push button. The push switch marked "Train Stop Override" is used to pass a signal at danger with authority. It ignores the TPWS TSS loops for approximately 20 seconds (generally for passenger trains) or 60 seconds (generally for slower accelerating freight trains) or until ...
In the event of a hazard, the task of safety functions (e.g. E-STOP, safety gate or standstill monitoring) is to use appropriate measures to reduce the existing risk to an acceptable level. These many safety functions include: Emergency stop pushbuttons; Safety gates; Light beam devices; Pressure sensitive mats; Two-hand controls; Time delay
To make a PLC fail-safe the system does not require energization to stop the drives associated. For example, usually, an emergency stop is a normally closed contact. In the event of a power failure this would remove the power directly from the coil and also the PLC input. Hence, a fail-safe system.
Emergency Brake Handle on Bombardier commuter rail equipment, Sounder, Seattle, WA. In the USA, an emergency stop cord is not used. Any visible cord running within the body of a railway car would have been what was known as the "communicating cord". This was a method of signalling the engine operator (known in the US as the "engineer").
The above realizes the function: Run = (Start OR Run) AND (NOT Stop) This latch configuration is a common idiom in ladder logic. It may also be referred to as seal-in logic. The key to understanding the latch is in recognizing that the "Start" switch is a momentary switch (once the user releases the button, the switch is open again).
SCRAM button at the Experimental Breeder Reactor I in Idaho. Sometimes the switch will have a flip cover to prevent inadvertent operation. A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction.