Pulled tail is the colloquialism referring to the act of a guard or conductor of a railway to apply the emergency brakes when something unexpected has been noticed. This could be an excess of speed in a section of line known to have a lower speed, or strange noises and shaking that might indicate that the train has derailed or something has broken.
In the United States, local colloquialisms include 'pull the air' or 'big hole' as verb phrases describing this same action. In the UK, colloquially the guard would drop the tap and the passenger pull the chain to apply the emergency brake.
In the days before modern electrical communications, pulling the tail briefly was a way the guard could communicate to the driver that say a conditional stop was required at the next station.
Accidents preventable by pulling the tail:
Waterfall train disaster
Eschede train disaster - conductor fails to heed passengers complaint about strange goings-on.
Sutton Coldfield rail crash - guard (conductor) made a brief brake application, but was reluctant to take control from the driver.
2008 Chatsworth train collision - Engineer (Driver) did not report last two signals as required by rules, but conductor (guard) did not pull tail.
Winsford (1948) - A soldier on leave, himself a former signalbox worker, pulled the chain (emergency brake) of the train in order to exploit a short cut to their home. It took some time for train crew to find and rectify the triggered brake. In the meantime, a following train ran past a red signal and collided with the first trains, causing casualties. The soldiers did own up to pulling the emergency cord without good reason.
Norton Fitzwarren rail crash (1940) - strange noises on second train, chain pulled, nothing found, train restarted.
In the Violet Town railway disaster, there was no train radio for the driver to report the position of signals to the guard, while guard in rear car would have poor if any view of the green signals. Note that signals change to red as the engine passes them, so that the guard rarely has a good view of yellow or green signals. It is not clear if any intercom connected the driver and guard.
