An emergency brake is a separate brake system in a vehicle for use in case of failure of the regular (hydraulic or air) brakes and commonly used as a parking brake in automobiles. Also called hand brake, many people shorten emergency and call the devices e-brakes.
In trains, control of emergency brakes is made available to the traveling passengers. Activating the brake will cause the train to automatically stop. Severe fines are often in place to dissuade people from activating the brake without good reason.
Use in the UK
This type of equipment was introduced to the United Kingdom by the Regulation of Railways Act 1868. Section 22 stated that "All trains travelling a distance of more than 20 miles without stopping are to be provided with a means of communication between the passengers and the servants of the company in charge of the train." At first, this means of communication was a cord running down the length of the train at roof level outside the carriages, connected to a bell on the locomotive. When the use of the automatic brakes was made compulsory in the Regulation of Railways Act 1889, the equipment was modified so that it operated the brakes, but the name communication cord has survived to the present day.
In most rolling stock built since the 1980s, passenger communication handles (PassComms) have been installed. When a PassComm is activated, an alarm activates in the driver's cab. The driver has around 3 seconds to press an override button, otherwise the brakes automatically apply. He must then stop the train in a safe place (i.e. not in a tunnel, or on an overbridge) and investigate the emergency. The driver can also speak to the person who pulled the handle, via a speaker/microphone mounted alongside the handle.