Locomotive Power, is the driving or pulling power of railroads. The Locomotive or engine pulls and/or pushes the train. It seems the word Locomotive and engine are completely interchangeable.
the word engineer comes from the steam engine. It literally means that "the controller of the steam engine." It was a time when there was a great mystic around the steam engine during the industrial revolution and well there should have been, it was changing the world. With the advent of trains the guy who drove the train engine was an engineer, Think about it, this guy could magically transport you to the other end of the world, at a time when the second fastest transportation was the horse and when most people still rarely traveled far from where they were born.
Locomotives/engines come in three general types. divided by how the tractive power is generated.
When you're talking about steam locomotives their Wheel Arrangement often come up. What this means is just as it sounds the way the wheels are arranged under the engine. There are often three sets to this, for the three functions of the wheels sets. While all steam engines have driver wheels, they are the big powered wheels, there are usually steering wheels in front on the pilot truck. It was learned early on in the history of railroads that having smaller wheels in front of the drivers made the engine safer, they helped to steer or piloted the engine in to curves. Then as engines got bigger and the cab end usually the back end, where the engineer and stoker are, began to extend out farther from the drivers, wheels were needed to support the cab. They are usually the same smaller size as the pilot wheels. So when talking about the wheel arrangement the pilot wheels are the first set, then the drivers, and the final set are those supporting the cab, in the trailing truck. Now looking at the wheel arrangement numbers, an engine such as a Yard Goat, which would rarely go fast but might be strong would be a 0-8-0. This engine has no steering wheels eight drive wheels on 4 axles and no back wheels, from one side it would look like this OOOO. In the case of a heavy passenger engines like a "Mountain," we would call it a 4-8-2, looking like this ooOOOOo. Having four steering wheels on two axles, eight drive wheels on 4 axles and two wheels under the cab. There are several steam locomotives so big and long that they have to articulate in order to handle turns in the tracks. The most powerful engine ever made was one of these, the Allegheny, 2-6-6-6, had wheels like this oOOO OOOooo. The Big Boy, 4-8-8-4 was the heaviest engine built and looked like this ooOOOO OOOOoo. All these Articulated steam engines are often called Mallets. Very unusual was the Triple Articulated engine, 2-8-8-8-2, oOOOO OOOO OOOOo, a very long engine, very complex to build and run. Most of these Mallet engines came about only at the end of the steam era, the 1940s, as they tried to get more power out of the locomotives. Sadly for the steam engines, they could not compete with the economies of the diesel electric engines quickly improving since their introduction in the 1930s. By 1950 it was the time of the diesel engines/
The Allegheny 2-6-6-6
The Chesapeake and Ohio (C&O) Railroad’s 2-6-6-6 Class H-8 Alleghenies were the most powerful reciprocating steam locomotives to be built anywhere in the world. Designed by the Lima Locomotive Works, sixty Alleghenies were delivered to the C&O from December 1941 until December 1948.
With a weight of more than 775,000 lbs and a boiler pressure of 260 psi, they could develop a tractive effort of 110,200 lbs and generate 7500 horsepower at 40 miles per hour. Their boilers were capable of delivering 8000 horsepower. This, coupled with their 67-inch diameter drivers, gave them a wonderful turn of speed however they were rarely used in high-speed operations.
While most of American industry was in a terrible economic slump during the 1930’s, the C&O was busy constructing new tunnels, laying double track, rebuilding bridges and generally upgrading their system. This fortuitous situation was because of the main product that they transported – coal. Some of the finest bituminous coal deposits in America were adjacent to the C&O routes and coal was needed even during a poor economic climate.
In the late 1930’s, it became evident that the C&O would need additional motive power for the 80 mile coal run between Hinton, West Virginia and Clifton Forge, Virginia. This route crossed the Allegheny mountains and included a 0.58% 13 mile grade up to a 2,072 foot summit and a descent of 1.14% into Clifton Forge. The C&O was currently operating Texas class 2-10-4s and planned to procure additional locomotives of this class until Lima approached them with their new and somewhat novel 2-6-6-6 design.
The new locomotive was to weight over 775,000 lbs and would utilize four 22.5-inch diameter cylinders with a 33-inch stroke. The articulated chassis would carry a huge boiler with a 9 ft x 15 ft firebox containing 135 square foot grate. The resulting rear weight required a six-wheel trailer truck to support it. The tender would be the largest ever designed for the C&O, weighing over 430,000 lbs, and would have a 25,000-gallon water tank and a 25-ton coal bunker.
The over all length of the locomotive and tender was limited by the length of existing turntables so the tender was designed to be short and its rear section was designed “high” to carry a great deal of weight. This configuration required an eight-wheel rear tender truck to distribute the load to the rails. The forward tender truck had six wheels.
The final length of the locomotive and tender was slightly over 125 feet. The increased power and improved economics of the new design over the Texas class was the deciding factor. The C&O selected it and never regretted their decision, as it would prove to be one of the finest locomotive designs in American railroad history. The name “Allegheny” was given to the new giants in honor of the mountain range over which they would be operated.
Standard operating procedure for the coal run was to use two Alleghenies, one pulling and one pushing, to haul a 140-car train. Starting at Hinton, the train would climb the steep grade up the mountain to the summit when the pushing locomotive would be uncoupled and turned for its descent back to Hinton. The lead locomotive would then proceed down grade with the train into Clifton Forge. There it was turned and sent back to Hinton hauling a string of empties.
The first ten locomotives were delivered in December 1941 and were immediately pressed into service to meet the demands of World War II. The performance of the Allegheny was so impressive that the C&O ordered an additional ten locomotives, Numbers 1610 through 1619, which were delivered in 1943 and another 25, Numbers 1620 through 1644, which were delivered in 1944.
During the war, the C&O had 23 of its Alleghenies modified to include steam heat and signal lines for passenger service but used them only rarely to haul a troop train or heavy mail train. Their more normal assignment was to haul a 10,000-ton freight train at the slow rate of 15 miles per hour. This is in stark contrast to their design goal of hauling a 5000-ton train at 45 miles per hour. Thus the Alleghenies were never given the opportunity to demonstrate their full potential.
A final fifteen locomotives, Numbers 1645 through 1659, were delivered in 1948 making a total of sixty Alleghenies on the C&O roster. They continued to give faithful service over the post war years but they were eventually replaced by diesels staring in 1952. The last Allegheny was removed from service in 1946.
The Virginian Railway also operated eight 2-6-6-6 Lima built locomotives during World War II, which were essentially identical to those of the C&O however they were know as the Class AG Blue Ridge. Delivered in 1945, they were used in coal hauling operations. They operated well into the 1950s but were all scrapped by 1960.
The Big Boy 4-8-8-4
Eventually, every railroad faces the same problem: how to move trains over mountains? Small logging and mining railroads purchased geared locomotives -- Heislers, Climaxes and Shays -- which could pull trains at low speed up steep hills. Medium railroads, like the Delaware, Lackawanna & Western, bought lots of medium-sized engines -- 4-6-2s, 4-8-2s and 4-8-4s -- and put as many as ten engines on one train. Large railroads like the Union Pacific Railroad, stretching from Kansas City, Missouri, to Omaha Nebraska in the east to Seattle, Washington in the northwest and Los Angeles, California in the southwest, preferred a different solution. The Union Pacific ordered larger, more powerful engines such as the 4-12-2 Union Pacific type and the 4-6-6-4 Challengers. The trend toward size and power culminated in the 1.2 million pound, 6,200 horsepower 4-8-8-4 Big Boy.
The Big Boys were built for power. They did the work of three smaller engines, pulling 120-car, 3800 ton freight trains at forty miles per hour in the mountains of Utah and Wyoming.
With power though, comes weight -- larger cylinders, pistons, drive rods, boiler, firebox. Steam locomotive manufacturers added more wheels, both powered drive wheels and unpowered idlers.
The extra wheels added length. Long engines had difficulty squeezing through the sharp corners in mountains. A French designer named Anatole Mallet added a hinge to the middle of a locomotive to allow it to bend. Two pairs of cylinders supplied power to the two sets of drive wheels.
The Big Boys were built in Schenectady, New York by the American Locomotive Company (ALCo) to the Union Pacific's design. ALCo delivered the first batch of 20 (including the 4012 in the Steamtown NHS collection) in 1941 and the remaining 5 in 1944.
Big Boys had over one mile of tubes and flues inside the boiler. Their firebox grate measured 150 square feet. The Big Boys had sixteen drive wheels, each measuring 68 inches. From coupler to coupler they measured 132 feet 9 inches. The tender held 24,000 gallons of water and 28 tons of coal and the engine and tender weighed 1,189,500 pounds in working order. The engines well deserved the name 'Big Boy' which was written on one of the drive rods by an unknown worker at ALCo.
The 25 Big Boys were built to pull long fast freight trains over the Wasatch Mountains of Utah and Sherman Hill in Wyoming. They served there until 1959 when the new diesel-electric locomotives took over. The Big Boys were not the most powerful engines, though they were the heaviest. But no engine ever came close to matching Big Boy's combination of speed, power and agility.
The Challengers 4-6-6-4
Challenger: Union Pacific at one time owned 105 Challenger locomotives. Built between 1936 and 1943, the Challengers were nearly 122 feet long and weighed over one million pounds. Articulated like their big brother, the Big Boy, the Challengers had a 4-6-6-4 wheel arrangement. They operated over most of the Union Pacific system, primarily in freight service, but a few were assigned to passenger trains operating through mountain territory to California and Oregon.
Union Pacific Challenger No. 3985 was designed by Union Pacific and built in 1943 by the American Locomotive Company. It is one of 105 Challengers built for Union Pacific between 1936 and 1943 and is the only operating engine of its class in the world today--the largest and most powerful operating steam locomotive.
The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. Each set of driving wheels has its own steam cylinder. The result, in essence, is two engines under one boiler.
The frame of the locomotive is "articulated," or hinged, to allow it to go through curves. When watching the approaching locomotive go through a curve, you can see the boiler swing out left or right independently of the lower half of the engine, as the rear half of the locomotive remains in a straight direction until its wheels and frame are halfway through the curve.
The Challengers were designed for fast freight service, but occasionally pulled passenger trains. No. 3985 originally burned coal and pulled a tender with a 32-ton capacity. In 1990, it was converted to use No. 5 oil. The top speed of No. 3985 is about 70 miles an hour.