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Very true on this aspect. I am termed as a nut case to spend a couple of hours every week heading to various railway stations to observe these beasts.

Once I go back home, let me upload a few pictures and contribute to this thread.

Cheers.

Engine at the back is only used for Braking/Banking. Especially when the train is up or down the ramp. (steam engine hauling toy trains are not in this discussion)

More than one engine in the front can be because more reasons. You will typically see only diesel locos more than one being attached in the front. That can be the case when you need power of both locos to haul the train. Superfast trains with more than 22 rakes typically have two diesel locos (WDM4 class). This helps achieve a max speed of 110-120kmph. Classic examples being TN, GT, AP, KK, Kerala etc.

If the train is hauled by an electric locomotive (WAM4/WAM5/WAM7 etc), then you will only see one loco attached in the front. Because its powerful enough to haul the who train at the rated maximum speed.

An extra loco (typically a diesel) can also added in the front for the same braking reasons for which they are added in the back.

Two locos upfront are normally used in a many trains (long rake super fasts) like Karnataka express , and is a common sight.

One loco in the front and other at the back is used only in ghat sections. The trailing loco is a banking loco. The aim is to reduce the load on the couplings when negotiating the steep gradients.

The best a rail fan can ask for is to travel behind twin ALCOs, almost EMU like acceleration and the wonderful chugging sound so typical of the ALCO locos

Also, whenever I travel by train one of the things I notice and try to understand is how the coaches handle braking from the engine. Are all the coaches' brakes controlled from the loco engine or is it that the driver applies brakes on the engine and the coaches that run behind the loco bombard onto the ones in the front and decelerate?

Yes, when the engine driver brakes, the brakes of all the coaches operate in tandem.

Wow a great thread....read all through it now. Brings back all memories of my childhood and those long journeys from Pune to Trivandrum and Pune to Chennai, when i used to jot down all the WDM's and engine serial nos. in a small notebook. Never understood what all that Rail jargon meant until today. Thank you so much Gansan.

Now to trace out my little old notebook

Ok, that brings to another question - Not all the coaches' brakes will have the same bite, so, in case a few particular coaches have tight breaking and a rest few not so tight and don't decrease the speed as with others, wouldn't that affect the balance of the train on track? How is that controlled?

I think you mean 22 or more carriages here ?
The link up of a set of carriages in a train (or the whole set of carriages) is termed as a Rake.

Sorry my mistake. I should have said compartments/carriages and should not rake.
Thanks for correcting.

My 2cents here.
Not directly answering your question, but just some info for others who might be interested.

The older technology used in carriages were vacuum brakes, now they are all replaced by air brakes. If you observe the connection between 2 carriages you will see a black pipe (flexible one) running across. In junctions where they have to attach a coach, you will see the guy who couples them also connects these 2 black pipes between the carriages. I believe this is what controls the braking across carriages and are manned from the Engine.

Another point, If you pull the STOP Chain inside the carriage , it engages the brakes of the current carriage, and I believe some indicator in the Engine goes off.

Also if you observe the end of the outside of the carriage you will find a vertical lever sticking out. When the stop train chain is engaged in a compartment this lever flips from a vertical to a horizontal position. This lets the driver guard identify the carriage from where the chain was engaged just by glancing through the line of carriages.

I don't have a pic of it, maybe next time I pass a train will click one.

I don't think just the brakes of the coach in which the chain has been pulled is engaged. Whenever the brakes engage, it will be for all the wheels of the train. Engaging only the brakes of one coach suddenly may derail the train.

Whenever the train is stopped, all the brakes remain engaged. If we listen carefully, we can hear them disengage just before the train moves. If any of you travel by EMU trains, this will be more noticeable. As you mention, we can observe the air brake pipes being connected whenever a loco is attached to a train. If you stick around, you can also hear the compressor running for a few minutes and the brakes being bled. As for Cliffhanger's query about all the brakes not having the same bite, I really don't know. There must be some indication in the loco for this or there must be a routine inspection check for them. Like how they check for overheating (red) axles - you might have observed some fellows crouching near the track on either side and looking at the wheels just before the train enters the platform , with a flourescent light focussed at night times - well, they are checking for this! If there are any railway engineers on the forum, they can clarify better!

As for the indication for chain pulling, there is a red flag like equipment at the top in between the coaches, which will be raised in that particular coach.

A couple of snaps from my end.

WDM3A from Erode with the Miyalathudurai Express chugging up hill near Bidadi towards SBC - Bangalore City



KJM - Krishnarajapuram WDG3A with Chamundi Express going downhill towards MYS - Mysore. This seems like an off-link.



To add to the discussion about the brakes in a train. Here is my 2 cents.

There are 3 types of braking system (air and sometimes dual circuit - Vacuum and Air), namely engine/loco brakes, guard brake and dynamic brakes.

The dynamic brakes will be enabled as a rake is coupled with the Loco. I will try and get the picture from the EMD WDP4 Engines or probably from google. The lever of the Dynamic brakes pulled towards the Loco pilot will act as an accelerator and brakes when pushed.

This is something like this.


-2
-1
0
1
2

When the lever is pushed towards -2 the brakes engage and when it is at 0, the loco pilot would engage the parking brakes. When the lever is engaged towards 2 the same lever works like an accelerator.

My hunt is on for the pic.

Here is one from my side. This video was taken last Jan. The MAS - BZA Jan Shatabdi crosssing the Krishna Bridge. The train passing an iron girder bridge is music to my ears, in most cases they are passing alone slowly generating a nice rhythm of music.

I remember as kids when we used to make the almost annual trip to Vishakapatnam by the Coramandel express we used to drop coins at almost all major rivers.

YouTube - ‪Krishna Bridge‬‏

What did you mean by this?

Nice pictures btw. Looks like you literally sat on the adjoining track for the shots.:)

The off-link is an irregular loco coupled to the Rake. I was expecting a WDP4 from KJM for the Chamundi Express. Tippu express does get one. Hence the word off-link.

Not sure if it really was an off-link.