GUIDE TO LOCOMOTIVES AND TRAINS

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There are to major suppliers of traction to the american railroads: General Motors Electro Motive Division (EMD) and General Electric (GE). Below is a guide to distinguish between the different american locomotives.

But first a little about how builders and railroads designate locomotives as this sometimes can be a little confusing.

EMD: EMD 4 axle locomotives are called GP (General Purpose), EMD 6 axle locomotives are called SD (Special Duty). The number that follows do not indicate the power of the locomotive, but the higher the number, the newer and more powerful is the locomotive as a basic rule. The suffix behind the number has the following meaning: AC = AC traction, M = Safety Cab, T = Tunnel motor.

GE: "B" indicates a 4 axle locomotive, "C" indicates a 6 axle locomotive. The number is the number of horsepower divided by 100 (so 44 is a 4400 horsepower locomotive). The number after the dash gives som kind of indication of how old the model is - but the newest locomotives doesn't follow this rule. A "W" means widecab or safety cab.

Besides, the railroads often use another classification.

Another way to find the model if you have the railroad and the locomotive number is to use a roster like The Diesel Shop.

GE C40-8W

The DASH 8 can be found with both the traditionel cab and the new safety cab, and also with two power outputs (C40 = 4000 hp, C41 = 4100 hp). The newest DASH 8 are very similar to the DASH 9 - but look at the trucks, the DASH 9 has high adhesion trucks.
1. Trucks - not the new high adhesion type.
2. "Wingshaped" cooling air intakes.
3. GE characteristic angular fuel tanks
3. GE wide cab (but some models have the traditionel cab).

GE C44-9W

1. "Wingshaped" cooling air intakes.
2. High adhesion truck - these are found on DASH 9, AC4400 and AC6000.
3. GE wide cab
4. GE characteristic angular fuel tanks - on the right side is two air tanks for the braking system.

GE AC4400

1. GE wide cab
2. Large AC equipment box on the left side of the locomotive - the GE C44-9W has a smaller equipment box, also on the left side.
3. "Wingshaped" cooling air intakes.
4. High adhesion truck.
5. GE characteristic angular fuel tanks.

GE ES44DC

The new Evolution Series is very similar to C44-9W and AC4400 locomotives, but look for:

1. Cooling air intakes are larger than on C44-9W and AC4400.
2. Large equipment box on the left side (also found on the AC4400).

GE AC6000

The AC6000 is a very long locomotive, but else quite similar to DASH 9 and AC4400 in appearence. But the extra large "wings" and the position of the air tanks on the right side, and a large AC equipment box on the left side reveals a AC6000.

1. Extra large cooling air intake "wings"
2. The position of the air tanks.

I have found that UP and CSX seems to have different trucks on their AC6000's, so this isn't a unique feature.

GE AC4400CW vs GE C44/60CW

Air intakes on a GE AC4400 CW (front) versus a GE C44/60CW (back, very much identical to AC6000) - the difference is noticeable.

GE P42DC

P42DC is used for passenger trains. Most are owned by Amtrak, but also a few local companies use this locomotive. A P42 looks completely different from most other american locomotives. The most significant design features must be 1) no nose and 2) a very "boxy" design.

EMD GP30

This model is quite easy to recognize because of the special roof design. The type on the picture is a GP30u

1. Traditional nose.
2. Roof design - this is not found on any other EMD.
3. 2 axle trucks.

EMD SD40T-2

The T-model is a speciel version of the SD40 designed for operation in long tunnels (T = tunnel). The air intake is placed lower than the normal SD40. As the warm exhaust gasses is exhausted at the top of the locomotives, a high placed air intake is more likely to cause the engine to overheat. Therefore the T-model has lower placed air intakes.

1. Traditional nose.
2. EMD rounded fuel tanks.
3. Low placed cooling air intakes - this is only found on SD40T-2 and SD45T-2.

EMD SD60

EMD SD60 has a traditional cab. More "clean" appearance than a SD40-2 and GE's.

1. 3 radiator cooling fans.
2. 3 axle trucks.
3. Traditional cab.
4. Location of central air intake, dynamic brake intake and rounded blower duct on the left side.

EMD SD70

EMDs SD70 has only been bought by Norfolk Southern and Illinois Central. It's basically a SD70M with a traditionel cab.

1. Traditional cab
2. Box on the left side just after the cab.
3. Blower duct with a different appearence than on SD60.
4. Relatively "clean" appearance.
5. 3 axle trucks of a more modern design than SD60.
6. Rounded fueltanks.

EMD SD70M

Especially Union Pacific has a very large roster of EMD SD70M. Very similar to the SD70MAC (below)

1. Modern wide-cab with two-piece windshield.
2. No blower duct on the left side.
3. Notice the cooling air intakes, on some SD70M's they are slighly slanted (like this on), on others they are not.
4. 3 axle trucks.

EMD SD70MAC

EMD SD70MAC is an AC-version of SD70M. BNSF has almost 800 of these locomotives for use on heavy coal trains. The SD70MAC is very similar to the SD70M, but notice 3) and 4), they can tell a MAC from a normal SD70M.

1. Modern wide-cab with two-piece windshield.
2. EMD rounded fuel tanks.
3. Extra air intake on each side for the inverters.
4. Rounded blower duct on the left side.

EMD SD70ACe

One of EMDs newest locomotives with a very "boxy" design. This locomotive in many ways look more like a GE than an EMD (nose and fueltanks).

1. Very "boxy" wide-cab.
2. Angular fueltanks like GE locomotives.
3. Roof detail.
4. Large cooling air intakes, like EMD SD90MAC/SD9043MAC.
5. Large equipment box on left side.

EMD SD90MAC

1. Wide cab EMD style - however some EMD SD90MAC's have a different cab (like the SD70M-2 and SD70ACe).
2. Roof detail - different on EMD SD9043MAC.
3. Large cooling air intakes.
4. The characteristic rounded EMD fuel tanks.

EMD SD9043MAC

EMD SD9043 is basically a SD90MAC with a smaller engine.

1. Wide cab EMD style.
2. The cooling air intakes.
3. The characteristic rounded EMD fuel tanks.

Specifications

General Motors Electro Motive Division (EMD)
Model	Wheel arr.	Power	Cyls.	Weight	Tractive effert (start/cont.)	Max. speed	Built
GP38-2	B-B	1500 kW /2000 hp	16	114 t	?/26 t
SD40-2	C-C	2200 kW / 3000 hp	16	167 t	?/38 t
SD45-2	C-C	2650 kW / 3600 hp	20	167 t	? / 38 t		from 1965
SD50	C-C	2575 kW/ 3500 hp		167 t	? / 44 t		1981-1985
SD60	C-C	2800 kW/ 3800 hp	16	167 t	? / 45 t		from 1984
SD70M	C-C	2900 kW / 4000 hp	16	167 t	72 t/49 t
SD70MAC	C-C	2900 kW / 4000 hp	16	189 t	80 t/62 t	75 mph / 120 kmh	from 1993
SD70ACe	C-C	3204 kW / 4300 hp	16		87 t/69 t	70 mph / 113 kmh
SD80MAC	C-C	3700 kW / 5000 hp	20	191 t	? t/67 t	75 mph / 120 kmh
SD9043MAC	C-C	3160 kW / 4300 hp		191 t	? /70 t
SD90MAC	C-C	4400 kW / 6000 hp	16	193 t	91 t/77 t	75 mph / 120 kmh

General Electrics
Model	Wheel arr.	Power	Cyls.	Weight	Tractive effert (start/cont.)	Max. speed	Built
C40-8W	C-C	2900 kW / 4000 hp	16	177 t	?/49 t	65 mph / 105 kmh	from 1989
C44-9W	C-C	3200 kW / 4400 hp	16	185 t	64 t/48 t	73 mhp / 117 kmh	from 1993
ES44DC	C-C	3240 kW / 4400 hp	12	188 t	75 t/?	75 mph / 120 kmh	from 2004/2005
AC4400	C-C	3240 kW / 4400 hp	16	187 t	82 t/?	75 mph / 120 kmh	from 1994
AC6000	C-C	4400 kW / 6000 hp	16	187 t	90 t/83 t	75 mph / 120 kmh
Genesis I / P42DC	B-B	3100 kW / 4200 hp	16	122 t	? / 18 t	110 mhp / 176 kmh

A little about train physics

Above is data for different locomotives. Let's use these data. Basic physics says that power = force X speed. For a locomotive force is the tractive effort. A modern locomotive has for example 4400 hp ~ 3200 kW. If we put this power into the equation we get: 3200 kW = force X speed. With a speed of 50 km/h (= 31 mph = 13.9 m/s) we get force (tractive effort) = 3200 kW / 13.9 m/s = 230 kN ~ 23 ton.

Higher speed means lower tractive effort. And lower speed means higher traction effort - until the maximal friction limit between wheel and rail is reached. For a typical locomotive the friction coefficient is about 0.3 - this means the tractive effort of a locomotive weighing 180 ton can't exceed 0.3 X 180 ton = 48 ton ~ 480 kN. In the diagram on the right is the schematic relation between speed and tractive effort for a typical (fictive) locomotive.

The tractive effort is used to haul a train. A train running with constant speed has a resistance that is the sum of rolling friction, air resistance and the gravity (= the grade). On a train going uphill, the grade component (or the gravity component) is by far the most important (if the uphill grade is significant)

An example: a 5000 ton train including locomotives is travelling over Goffs Hill in the Mojave Desert, California. Needles (altitude 160 m) is about 45 km from the summit (altitude 792 m). This gives a grade of 1.4% - this isn't extreme, but a very normal grade. This also means that trains don't need extra locomotives (helpers) as in for example the Tehachapi Mountains.

To haul a train up this 1.4% grade the locomotives must produce a force or tractive effort of 1.4 of 5000 ton = 0.014 X 5000 ton = 70 ton = 700 KN.

A typical train on Goffs Hills is hauled by 3 modern GE C44-9W's. This gives a total effect of 3 X 3200 kW = 9600 kW. If we put this and the needed tractive effort of 700 kN into the equation power = force X speed => speed = power / force, we get speed = 9600 kW / 700 kN = 13.7 m/s = 49 km/h = 31 mph.

AC versus DC

In the "old days" all diesel-electric locomotives were DC (= the current to the traction motors were DC), but in later years locomotives with AC traction motors have become available. AC-locomotives (as they are called) offers a better control over the traction motors, this eliminates or reduces wheelslip. This means more tractive effort at low speeds because the friction coefficient is higher. But the price for an AC locomotive is about 1,4 million USD higher than for a DC locomotive.

The railroads use these differences. On trains with high speed such as container and intermodal trains the locomotives is normally of DC-type. There is no need for the advantages of AC-traction and certainly no need for the higher cost of the AC-locomotive. On coal trains (= high weight, low speed) only AC-power is used. On such trains the advantages of AC-traction can reduce the number of locomotives needed for hauling til train, and this justifies the higher price pr. locomotive.

Examples of this can be seen on BNSF - they have a large fleet of GE C44-9W (DC-traction) that is used for many types of trains, including high-priority container and intermodal trains. On coal trains BNSF use EMD SD70MAC, GE AC4000W and GE44AC. On Union Pacific the same pattern can be seen; the standard locomotives is EMD SD70M (DC-traction), but on coal trains GE AC4000W, GE ES44AC and EMD SD9043 is used.

Types of trains and rolling stock

Below is a short description of the different types of trains and rolling stock found on american railroads.

Container trains ("stacktrains")

Containers are almost always transported in decicated container trains, often combined with trailers on flatcars (TOFC or "piggyback"). Container trains are often called "stacktrains" og "doublestack" because the containers are stacked on top of each other. Container trains use special cars like the examples on the pictures.

USA has a large import of goods from the Far East, these goods are transported in containers that enter the american continent via container ports like Los Angeles Harbour and Long Beach. From here the containers are transported by rail (and also some on trucks) to the Midwest and Eastern USA.

On container trains you will see containers from Mærsk/APM, APL (American President Line), China Shipping, J.B Hunt, OOCL, Evergreen, Hyundai and many more companies.

Double stack TTX car 75022.

Double stack car BNSF 236095C.

Double stack car Brandon Rail 5002.

"Grain-train" / covered hopper

A covered hopper is used for transporting goods that needs protection from wind and weather - this can be corn, cement, plastic pellets etc. Covered hoppers can be found in several different designs but can always be recognized by the discharge gates underneath. It is very common to see covered hoppers on block trains (trains that only have one type of rolling stock).

Autorack

An autorack is a specialized type of boxcar used for transporting cars. This is typically new cars being transported from a production plant or harbour to dealers/distribution centers. They normally have 2 or 3 levels, depending the size of cars being transported.

To protect the cars from damage, theft, vandalism etc. modern autoracks are closed.

Tank car

Tank cars are used for transportation of various forms of liquids or gases. Often it is possible to guess what's inside from the inscriptions on the car, but just as often is is not possible to see.

Procor PROX 23280 tank car

Cargill CRGX 5612 tankvogn

Cargill Foods CRGX 5612 tank car - it is written on the car, that it contains corn sweetener.