Well I have one doubt to clarify.

I heard like this somewhere don't remember exactly

The present day diesel engines used by Indian railways do they convert the mechanical power to electric power and then drive the wheels using a motor? .

Similarly during breaking a load is applied on the wheels so it reduces speed. .

Sir it was an electric one, which they changed to another at Kanpur.
But Sir on the same tracks if Shatabdi can run over 150kmph then... are the coaches of Shatabdi fit to run at more than 160?
At Howrah once I went to drop my cousin, then an empty loco was moving after the train departed, then I requested the driver to let me come over there I wanted to see the mechanism and he scolded me to get away...

Thats a good news about magnetic lev, I have had just heard about it being used since a long time in Japan etc. If you start discussing about the mag lev trains then I have a lot of things to clear about, will ask then only. After diesel are you moving to electric locos? Then please do come at the magnetic part later for sure.

And, in Kolkata metro, since they are quite old I doubt about their performance in comparison to Delhi metro. Plus, I dont know if they are using microprocessors controlled braking or not, but they are pretty aggressive..don't know whether poor suspension is also contributing in that


Edit: In your rough diagram of a diesel engine I saw "air intake" and "air compressor", how do they differ from each other?
Also, from the side view I see when a train is standing then a part of piston/hydraulic system like is in the relaxed state but just before they start to move then that thing gets inside (I guess it happens because driver releases the brakes?)
Also, what is that sound produced like compressed air is released for few seconds (even when the train is standing)

In Diesel Electric as the name implies the diesel engine is used to drive an Alternator which in turn provides the power for the motors attached to the wheels through gear system...Please go through previous pages for further clarifications...
In later models of Diesel Electric Locos, apart from the physical braking another form known as regenerative / Dynamic braking is also used. What is done is the Input to motor is totally disconnected ,and the motor is connected to a series of high power Resistors. The motor when not receiving input, and is also turning ,becomes a generator of electricity,and by putting resistors in it's output we are effectively loading the motor ,which in turns offers resistance to it's rotary movement.

Here is a Pictorial representation of Normal Traction,when the Axle motors are receiving power.





Here is what happens under Dynamic braking when the Motors are turned into generators and Resistors are used to load on the power from the motors to have Dynamic braking.

replies in bold.

Till a few years back, the max RPM of the Diesel Loco Engine was Limited by a Mechanical regulator.
The idling RPM was around 400 and the max was 1,000.These are called Speed Governors..... Here is a pic of the mechanical limiter ..



To accelerate the engine in tune with required Voltage ,current and hence Power from the Alternator, a throttle control was used...Here is a pic of the mechanism of the Throttle Control..



These two types of RPM and Throttle Control were widely used in the ALCO Diesel engines belonging to the WDM 2,and 3 class of engines.

Here are some Links to Indian Railways diesel Locomotives including information about the Diesel engine,type of drive(AC/DC) wheel configuration used,tractive effort etc.,....A MUST READ for getting in-depth Knowledge about the Diesel Traction in India...



Here is a link to most frequently asked question and Answers



And here is how the Indian railways system classifies it's Engines..

• W = Broad Gauge
• Y = Meter Gauge
• Z = Narrow Gauge (2' 6")
• N = Narrow Gauge (2')

The second item, '[power]', is one or two letters identifying the power source:

• D = Diesel
• C = DC traction
• A = AC traction
• CA = Dual-power AC/DC traction
• B = Battery electric(rare)

The third item, '[load]', is a single letter identifying the kind of load the loco is normally used for:

• M = Mixed Traffic
• P = Passenger
• G = Goods
• S = Shunting
• L = Light Duty (Light Passenger?) (no longer in use)
• U = Multiple Unit (EMU / DEMU)
• R = Railcar

Why does diesel engine convert it to electric power and then transmit to wheels? . Wouldn't there be high energy losses associated with it?

Or are the mechanical complexities too big to transmit power directly?

I wonder how many Indian railway engines will pass pollution test .

None of them bro...they have not even think about it, I must say...

Just imagine transferring the diesel engine power to the wheels through a clutch system....It will be a huge clutch,and imagine clutch failure half way through journey,and it's replacements,gear box it's SIZE and it's oil, and gear shifters etc.,There is infact a huge loss of power through this kind of transmission than with the electric system,due to the mechanical linkages involved. Added to that is the smooth delivery of high torque(about 3,000 HP) needed to move about 3,500 tons of load(coaches/wagons)....Electric traction is the way to go.
The Old ALCO 251 series used in India were not confirming to the pollution control norms..In fact one of the reason ALCO sold the company and wound up operations in US.The present generation ALCO engines in India are being fitted with Micro processor based fuel Injection system ,along with it's sophisticated Technology,and have become more Fuel Efficient and less smoky.
But the winner here is the GM EMD made WDP 4 Diesel which gives higher power(4,000 HP) and is almost smokeless...It is a TWO STROKE DIESEL.....an injected Two stroke design which is superior to the 4 stroke design,of the ALCO engine.

So that justifies it, too much moving parts means increased failure chances .

And a two stroke diesel engine almost smokeless . Wow!.
I hope for production line bikes in India with pollution less two stroke petrol engine.

Yes and the GM EMD diesel has Tier 2 certification for pollution control..In USA the present norm is Tier 3...Indian Railways is set to get their Diesel Locos to Tier 3 and also increase WDP-4 power from 4,000 HP to 4,500 HP.
It had been proved that a Two stroke engine with Fuel injection technology is least polluting and gives better Power and FE...Already there are conversion kits available abroad for small gasoline engines

Here is a video of the TWO stroke GM EMD Diesel starting...Notice any smoke ?

Cranking of a WDP4!! - YouTube

and here is a ALCO WDM 3A...4 stroke diesel..



and a IR modified WDM 3 C with Micro processor controlled Fuel injection,etc., spotted doing 115 Kmph...notice negligible smoke.....an example of Indian Railways at it's best innovation..

I think it is common for all diesels to emit black smoke under sudden acceleration.
Even my 1400cc IDI turbocharged diesel car does that.
May be due to rapid cooling of the cylinder by diesel as more diesel is injected than what it can burn ?

What we see as black smoke is the partial/unburnt diesel coming out as smoke. If the engine is suddenly accelerated ,and the amount of Air breathed in the inlet is less then the AFR becomes rich leading to this. In Manual injection this is very pronounced, while in MPF Injected it is less because the injectors instantaneously reduce the amount of diesel injected, based on sensor's input to the ECM.

Alco(?) V16 at Loco Workshop, Parel. Took the picture when we had a IV last year and when i was considerably nubile. I noted that the Turbo charger had its exhaust case connected in reverse, i.e the exhaust enters the casing from the lip (centre) and is thrown out from the side. Isnt the exhaust gases supposed to hit the impeller at an angle and then get thrown out from the centre?



^This is how its supposed to be, and in that turbo the exhaust comes in from where it is supposed to come out, and flows out from where it is supposed to come in, (if you check the previous pic closely, then it will be clear sorry for lack of any better picture)

At that time i felt that the thing is driven by the crank (i.e is a supercharger) and the exhaust blower sucks air from the exhaust port of the engine, to scavenge it better.

Later on i thought that the impeller in the exhaust casing would have been designed differently keeping in mind exhaust flow rate and pressure.

So which thesis is right?

Have some more pics to show you, is it possible to share fb albums here?


Also How 'exactly' does this xpressor work? the top half does the compression work and the crank does the vacuum work?

PS: thats not me in the picture.