We will now explore the second most popular and used Diesel Locomotive with Indian Railways, the General Motors (GM) Electro Motive Division (EMD) made diesel Loco GT46PAC, known in Indian Railways as the WDP-4.

Indian Railway started their Dieselization programme with setting up of Diesel Locomotive Works, Varanasi in 1961. DLW produced first Diesel Locomotive in 1964 with ALCO designed DC-DC traction system. Since then DLW constantly upgraded the technology in house and produced fuel efficient and power upgraded Diesel locomotives in line with growing needs of Indian Railways. In 1994, it produced first locomotive with AC-DC Technology which was maintenance free and more efficient as compared to DC-DC Technology.
In its quest for the State of the Art Technology, Indian Railways signed a Technology Transfer contract with Electromotive Division of General Motors of USA in 1995. With this TOT, DLW has started manufacturing locomotives with AC-AC Traction system.
The WDP-4 Technology employs a Three Phase Transmission system. In this system,rectified DC output of the Main alternator is fed to Traction Control Converter (TCC), which in turn inverts DC to controlled AC output and supplies to traction motors for locomotion. The inverters presently employed are Siemens make Voltage-Source Pulse Width Modulated inverters with Gate Turn Off Thyristor Technology.

Here is the picture of a WDP-4.

Here is WDP-4 brief Specification.....

FUEL .................................DIESEL
TYPE OF ENGINE.............. ....TWO STROKE
NUMBER OF CYLINDERS....... .." V " 16 CYLINDERS
BORE x STROKE.................. ..230.19 X 279.4 MM
TOTAL DISPLACEMENT........... 1,86,160 CC
COMPRESSION RATIO............ 16:1
FUEL DELIVERY..................... DIRECT UNIT INJECTION
AIR INLET............................ TURBO SUPER CHARGED
VALVE PER CYLINDER............. 4 EXHAUST VALVES PER CYLINDER
INLET.................................. PORT CONTROLLED.
POWER ............................... 4,132 H.P @ 904 RPM.
MAX TRACTIVE EFFORT........... 53,000 Kgs
TYPE OF DRIVE...................... ELECTRIC A.C. MOTORS...4
ALTERNATOR MAX VOLTAGE...... 2,600 VOLTS.

SUSPENSION.......................... NON-INDEPENDENT COIL SPRING AXLE HUNG WITH TAPERED ROLLER BEARING
BRAKES................................. AIR BRAKES DIRECT CONTACT ON WHEELS

ANTI-LOCK............................. RADAR BASED
ENGINE OIL............................. 950 LITERS
FUEL..................................... 6,000 LITERS
TOTAL LENGTH........................ 21 METERS
WEIGHT................................. 1,26,000 Kgs

PRICE..ON-RAIL....................... 11.5 CRORES.

Here is a look at some of the parts....
The rocker arm and cam assembly...


The Fuel efficient TWO Stroke engine inside the LOCO


The 6,000 liter fuel tank suspended beneath the Loco, and the cylindrical Air tanks above it..



The massive Three Phase AC Generator....



The High speed Turbo Super charger...



The Radar for Anti Lock Brake System..



The Engine in upside down position getting inspected...in the foreground are the Crank Shaft and Cam shaft...



The Cylinder head housing the FOUR valves...note the size...



The Powered wheels...The AC motors are arranged to be in between the wheels..



The Microprocessor Display system...




Indian Railways Train their Loco Engineers(Drivers) with state of the art facilities...and here is a pic of the simulator used in training.



and here is what it looks like inside the simulator.

Lots to read and lots to understand. Read it in brief now .

And pretty impressed with the simulator training.

And one doubt in diesel engines what type of valves are used? Is it sodium filled or hydraulic automatically adjusted type?. Or does they need frequent adjustments?

Please go back to page6 and you will see the V 16 cylinder with material id along with what it is made of...you will get clarification for all the parts there.
The valves are actuated by Roller Rocker arms by a common Cam...here is a video

EMD GP18 16-567D Engine Operation - YouTube

Sodium filled valves are supposed to transfer heat from valve face to valve stem at a better rate. Thought they are used because of these big heavy duty engines.

Also hydraulic valves automatically adjust clearance they dont need to be adjusted so frequently.

And thanks for the video.

PSR sir, I have a question:

As just a railfan, I know that the locomotives are numbered after their 1000 horsepower. And alphabets for 100 horsepower. So, WDP4 means 4000 horsepower. But as you said, modern Diesel engines move an generator which supplies electricity to electric motors, to make it easier for long journey.

So a WDP4 makes: POWER = 4,132 H.P @ 904 RPM. Is this from diesel engine's crank or the electric motors? If its 4132 at the diesel engine's crank, then how much do the electric motors receive?

In other words, what's the transmission efficiency/ loss, including the diesel to electric conversion?

If you noticed ,all the tappets have adjusting screw with lock nuts...so Valve clearance for 4 X 16 = 64 Valves have to be done periodically..

Thanks for a good question...The HP rating is for the Diesel engine,at a specific RPM...If the RPM is increased the HP also increases...The Alternators are directly connected to the Crankshaft and spins at the same speed as Crank
The calculated efficiency of the Electric Traction circuit and equipment is 95 %...so if the power is expressed as 4,000 HP ,only 95 % is actual power doing the work of moving the load....how ever in Diesel Electric Locos other means of expressing useful power also comes into play..ie., Tractive Effort and Draw bar...
Tractive effort is simply the force exerted at the wheel rim of the Loco and is expressed in Pounds(Lbs) or in Kilo Newtons(KN).
Horse power is defined as the work done by a horse to lift 33,000 Lbs to One feet in one Minute.In Metric system power (Watts) is calculated as power needed when One Newton of force is moved to one meter in one second...in actual terms it is expressed as a horse power which is equal to 746 watts....
The relationship between Power and Draw bar pull is that a low speed and a high draw bar pull ,can produce the same high power as high speed and low draw bar pull.
So it is clear that if you need higher Tractive effort and Higher speed you need to increase the power.

In a Locomotive, The Voltage fed to the Traction Motor determines the speed , while the current in Amps produces the torque to pull the load.In other words at start the Motors will be consuming High Current at low Voltage for pulling power ,and at higher speeds the current will be less and Voltage will be high.

RDSO of Indian Railways was constantly looking for improvement to existing rolling stock(Locomotives),and so along with improvements to the ALCO 251 engines, The GM EMD engines were also enhanced in performance...Many of the GM's engine and Locomotive properties were incorporated into the ALCO engine and locos..like the AC-AC Traction, enhanced braking circuit, Microprocessor controlled Fuel Injection and Electronic Braking control,increased Turbo charger RPM and efficiency,etc...Similarly at later stages for heavy load hauling in WDG GM Locos, the ALCO wheel set configuration was found to be better and the GM's Bo1-1oB was changed to ALCO type Co-Co..
Since the GM engine was covered by the TOT agreement between IR and GM, no immediate modification could be done . So IR looked for other area, and found that replacing the GTO type of Traction Controller with IGBT type will not only reduce power dissipated as heat in the TCC, but also enable improvement in max HP due to conservation of wasted energy by using efficient TCC management...
This led to the design and development of the 4,500 HP Loco to be named as WDP 4 B., and IR also made another change of having leading front end cab at both ends of Loco and was known as the WDP 4 D.(Dual Cab).
By changing the gearing ratio between Drive Motor and the Wheel gear , The same engine was made into a Goods Hauling engine and Identified as WDG 4, & 4 B..These became the workhorse of the emerging IR.
The First WDG with IGBT Technology was number 12102...and rolled out of Kashi on 4 th November 2006.....



1.Lowering of TCC temperature meant that cooling blower was redundant for IGBT TCC,,This saved 1 LAKH for every Loco produced.The TCC controller which was a 16 bit for GTO TCC was replaced with a 32 bit type for the IGBT TCC. This further gave much better load and overall performance improvement.
The 16 bit TCC controller



the 32 bit IGBT TCC controller...



GTO TCC with Blower ............................... IGBT TCC without blower



..............

2. The IGBTs were smaller and less bulky..this saved space inside Loco and the space was used up for housing Hotel Load generator...generator to supply the coaches with power when it is not moving, below is the pic., of the IGBT TCC with plenty of space at top of cabinet for the Hotel Load generator.(solid state).





The whole TCC unit getting installed on to the Loco chassis...notice the gaps all around....




With the power improvement to 4,500 HP the driven wheels were increased in WDG 4B to improve Tractive effort to pull more wagons and load.
So from Bo 1-1 oB the wheel allocation became Co-Co..ie., from 4 pairs of wheels with traction power to 6 pairs of wheels with traction power

Here is a Video of Starting the GM EMD GT46 PAC engine.Notice there is no smoke at all from the engine...

Cranking of a WDP4!! - YouTube

Here are some more pictures..Of the control deck,and some important internal areas of the GM EMD GT 46 PAC diesel electric engine...























The Electronics of GM EMD Locos are the fore runner for the up gradation of the 4,000 + ALCO 251 Locos which are now more powerful , and Efficient ,thanks to Microprocessor management of these Locos.

But even with all these Upgradation and Microprocessor management, the Diesel Locos are only 65 % Efficient....The Most Efficient of the Locomotives are the Electric Ones with upto 95 % efficiency.

We are now at the end of the Diesel Loco Infos, and ready to explore the Electric Locomotives.

Queries on Diesel Locos are most welcome....

@ psr : how do you knw so much about locomotives ??

really wanna know..

If you are really hungry you desperately search for food..till you get it...
I did the same..

Over head Power..

Direct and alternating current:

The most fundamental difference lies in the choice of direct (DC) or alternating current (AC). The earliest systems used direct current as, initially, alternating current was not well understood and insulation material for high voltage lines was not available. Direct current locomotives typically run at relatively low voltage (600 to 3,000 volts); the equipment is therefore relatively massive because the currents involved are large in order to transmit sufficient power. Power must be supplied at frequent intervals as the high currents result in large transmission system losses.

As alternating current motors were developed, they became the predominant type, particularly on longer routes. High voltages (tens of thousands of volts) are used because this allows the use of low currents; transmission losses are proportional to the square of the current (e.g. twice the current means four times the loss). Thus, high power can be conducted over long distances on lighter and cheaper wires. Transformers in the locomotives transform this power to a low voltage and high current for the motors. A similar high voltage, low current system could not be employed with direct current locomotives because there is no easy way to do the voltage/current transformation for DC so efficiently as achieved by AC transformers.

Rectifier locomotives, which used AC power transmission and DC motors, were common, though DC commutators had problems both in starting and at low velocities. Today's advanced electric locomotives use brushless three-phase AC induction motors. These polyphase machines are powered from GTO-, IGCT- or IGBT-based inverters. The cost of electronic devices in a modern locomotive can be up to 50% of the total cost of the vehicle.

Most systems have a characteristic voltage and, in the case of AC power, a system frequency. Many locomotives over the years were equipped to handle multiple voltages and frequencies as systems came to overlap or were upgraded.

Electrical circuits require two connections (or for three phase AC, three connections). From the very beginning, the trackwork itself was used for one side of the circuit. Unlike model railroads, however, the trackwork normally supplies only one side, the other side(s) of the circuit being provided separately.

However, railways generally tend to prefer overhead lines, often called "catenaries" after the support system used to hold the wire parallel to the ground. The most popular Contact collecting system on top of Locomotive,is the Pantograph: a hinged frame that holds the collecting shoes against the wire in a fixed geometry.

Modern electric locomotives, like their Diesel-electric counterparts, almost universally use axle-hung traction motors, with one motor for each powered axle. In this arrangement, one side of the motor housing is supported by plain bearings riding on a ground and polished journal that is integral to the axle. The other side of the housing has a tongue-shaped protuberance that engages a matching slot in the truck (bogie) bolster, its purpose being to act as a torque reaction device, as well as a support. Power transfer from motor to axle is effected by spur gearing, in which a pinion on the motor shaft engages a bull gear on the axle. Both gears are enclosed in a liquid-tight housing containing lubricating oil. The type of service in which the locomotive is used dictates the gear ratio employed. Numerically high ratios are commonly found on freight units, whereas numerically low ratios are typical of passenger engines.

India, where routes are electrified fully, operate under the 25 kV AC overhead wire. As of 2006, Indian railways haul 80% of freight and 85% of passenger traffic with electric locomotives.