हमसे सीखे कोई जीने का सलीका। सफर कैसा भी हो, मौज़ उडाये जाते हैं।। - Amir

Two Locos in Front for speedy movement Nd 1 or 2 Locos for Banking Purpose
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Question: What is a banker in Railway Terms?
Answer: A banker is a locomotive that assists in hauling a train up a steep gradient. A banker is attached to the rear of the train and pushes the train from the rear while the normal locomotive of the...
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train pulls it as usual from the front.
Bankers are used for two reasons. One is that, of course, the leading loco may need assistance on a steep gradient. However, a more important reason to have a banker at the rear when ascending a grade is to protect the train from a possibility of coupling failure and consequent parting which would cause a portion of the train to hurtle backwards because of the gradient (guard's brakes being generally inadequate for such a situation). When descending a grade, bankers may be attached at the front to provide extra brake power (or sometimes just to allow the locos to be returned to their shed after having banked trains up the grade earlier, without taking up a separate slot on the timetable).