Emergency brake (train)

On trains, the expression emergency brake has several meanings:

• The maximum brake force available to the engine driver from the conventional braking system, usually operated by taking the brake handle to its furthest position, through a gate mechanism, or by pushing a separate plunger in the cab.
• A completely separate mechanism from the conventional braking system, designed to stop the train as quickly as possible.
• A handle or plunger which may be applied by a passenger in an emergency, either stopping the train directly or sending an alarm to the driver so that they can stop the train.

Industry vernacular for when the emergency brake is applied is go into emergency, as in phrases like "the train may fail to go into emergency" or "the ability of the train to go into emergency is paramount".^[1][2]

The emergency brake applies considerably more braking force than the standard full-service brake. The engine driver or motorman will only use the emergency brake as a last resort, since it may cause damage; even with modern wheel slide protection, a train may develop wheel-flats, and the rails themselves can suffer profile damage.