Why does a goods train sometimes move backwards briefly before starting to move ahead from a stop?

18-07-2019

There are a few different reasons that this happens. One reason (and the official one stated in working timetables) has to do with ensuring the couplers (CBC's) along the rake are all engaged and locked before starting off. The backward push forces the couplers to engage if they are loose, not fully engaged, or if the coupler pins had been inadvertently (or maliciously) lifted while the train was stopped. Another reason is to compress the couplers along the length of the rake, so that when the loco starts moving forward, it has an easier time setting the wagons at the front in motion first before the rear wagons as the slack in the couplers plays out along the length of the rake -- it

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I’ve heard that some locos have ‘cruise control’. What does this mean?
June 20, 2019

Some locomotive classes such as the WAP-5 and WAP-7, as well as the WAG-9, have controls in the cab that can 'lock' the train to travel at a certain speed (the speed at the time the control or button is set). The button is known as the 'BPCS' button. The computerized loco controls then manage the tractive effort and braking effort and attempt to

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Why do trains sometimes feel like they are momentarily rolling backwards (or forwards) just after coming to a halt?
June 20, 2019

Today, almost all braking of trains moving at speed is done using the train brake system which activates (air) brakes along the length of the entire rake. The loco brake system is not used for bringing the train to a halt. However, as soon as the train comes to a halt, most drivers switch immediately to the loco brake system to hold the train at a

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What’s the cause of the characteristic jerk or momentary loss of power felt when a WDM–2 accelerates?
June 20, 2019

The WDM-2 loco, like most diesel-electric locos, has several configurations of its traction motors that are used as the loco accelerates from rest (Series Parallel - Series Parallel Shunt - Parallel - Parallel Shunt, and weak field configurations). There are three important transitions: At 30.8-39km/h 2S-3P Full Field to 2S-3P Weak Field, at

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What’s the method that IR uses to couple together multiple locos? or, What’s ‘Locotrol’?
June 20, 2019

Two to four or so locos can usually be coupled together to operate automatically, without any special provisions, with the crew manning only one of them. (This mode of operation is known as ‘Multiple Unit’ operation, or ‘MU’.) Using more than about 4 or 5 locos together without some form of automatic control for them is problematic

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What’s the ‘tractive effort’ of a locomotive?
June 20, 2019

The ‘tractive effort’ is a measure of how large a load the loco can pull and set in motion from a standstill — the maximum force it can exert at the drawbar or coupling. While the raw horsepower rating of the loco is important, it is not the whole story. The loco's weight also comes into play, as a heavier loco can pull a larger load without

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Other than diesels, were there other internal-combustion locos used in India?
June 20, 2019

For contemporary applications, see the section on alternative fuels. In 1905 Kerr Stuart delivered a 12hp 0-4-0 petrol-driven 2'6" loco to Morvi Railway and Tramways. In 1909, a railcar with a Dodge petrol engine was supplied to the Matheran Light Rly. In 1909, a 0-6-0 petrol-driven MG loco was supplied by McEwewn Pratt and Co. of Wickford in

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