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A steam turbine locomotive is a steam locomotive which transmits steam power to the wheels via a steam turbine. Numerous attempts at this type of locomotive were made, mostly without success. In the 1930s this type of locomotive was seen as a way both to revitalize steam power and challenge the diesel locomotives then being introduced.
There are two ways to drive the wheels: either directly via gears, or using generator-driven traction motors.
The route from Tucumán to Santa Fe, Argentina goes through mountainous terrain with few opportunities to take on water. In 1925 the Swedish firm NOHAB built a turbine locomotive similar to Fredrik Ljungström's first design. The condenser worked quite well - only 3 or 4% of the water was lost en route and due only to leakage from the tank. The locomotive had reliability problems and was later replaced by a condenser-equipped piston steam locomotive.
Two attempts were made in France. One effort, the Nord Turbine, resembled the LMS Turbomotive in both appearance and mechanical layout. The project was canceled and the locomotive was built as a compound piston steam locomotive instead. The second attempt, SNCF 232.Q.1, was built in 1940. It was unusual in that its driving wheels were not connected by side rods. Each of its three driving axles had its own turbine. It was heavily damaged by German troops in World War II and was scrapped in 1946.
Multiple attempts at this type were made by German locomotive builders. In 1928 Krupp-Zoelly built a geared steam turbine locomotive. The exhaust of the turbine was fed to a condenser which both conserved water and increased the thermal efficiency of the turbine. Draught for the fire was provided by a steam-driven fan in the smokebox. In 1940, this locomotive was hit by a bomb. It was withdrawn from service and not repaired.
A similar machine was built by Maffei in 1929. Despite having a higher-pressure boiler, it was less efficient than the Krupp-Zoelly locomotive. It was hit by a bomb in 1943 and removed from service.
Henschel converted a normal DRG Class 38 steam locomotive to use a steam turbine in 1927. [1] The locomotive itself was little modified, the major changes being to the tender which was fitted with coupled driving wheels in a 2-4-4 layout, driven by separate forward and reverse turbines. Both turbines were driven by intermediate pressure exhaust steam from the original cylinders. A condenser in the tender provided a vacuum for the turbine exhaust, increasing thermal efficiency. As the final exhaust was at negligible pressure, the original smokebox blastpipe had to be replaced by an electric draught fan in the smokebox.
Performance was disappointing, and the turbine tender was removed in 1937.
Giuseppe Belluzzo of Italy designed a number of experimental turbine locomotives. [2] [3] None were ever tested on main lines. His first was a small locomotive with four wheels, each fitted with its own small turbine. Reverse movement was accomplished by feeding steam into the turbines via a backwards-facing inlet. Steam turbines are designed to rotate in only one direction, making this method very inefficient. No one else appears to have attempted it.
Belluzzo contributed to the design of a 2-8-2 locomotive built by Ernesto Breda in 1931. It used four turbines in a multiple expansion arrangement. Belluzzo's US patent from that period shows the turbine driving a jackshaft through a gearbox in front of the locomotive's drivers. [4] This locomotive was never completely fitted out.
In 1933, a FS Class 685 2-6-2 locomotive was the object of a curious experiment, in which the piston engine was removed and a turbine fitted in its place, leaving the locomotive otherwise completely unchanged. Tests run were however a failure, as its performance proved to be well below that of a normal 685; the turbine soon broke up, and that signalled the end of the attempt. In 1936 the locomotive was refitted with a normal piston engine. [5]
Swedish engineer Fredrik Ljungström designed a number of steam turbine locomotives, some of which were highly successful. His first attempt in 1921 was a rather odd-looking machine. [6] Its three driving axles were located under the tender, and the cab and boiler sat on unpowered wheels. As a result, only a small portion of the locomotive's weight contributed to traction. In the mid-1920s, Ljungström filed a patent on a quill drive for a steam turbine locomotive. [7]
The second design was a 2-8-0 similar to a successful freight design. Built in 1930 and 1936 by Nydqvist & Holm, these locomotives replaced conventional ones on the Grängesberg-Oxelösund Railway. No condenser was fitted, as its complexity outweighed its thermodynamic advantages. The wheels were driven by a jackshaft. These engines were not retired until the 1950s when the line was electrified. Three engines of this type were built, all three of which have been preserved. These can currently be seen in the Railway Museum of Grängesberg, two (71 and 73) being owned by the Grängesbergbanornas Järnvägsmuseum (GBBJ) and the third (72) by the Swedish Railway Museum.
The Swiss firm Zoelly built a turbine locomotive in 1919. It was a 4-6-0 locomotive fitted with a condenser. It was fitted with a cold-air blower feeding into the firebox grate rather than a suction fan in the smokebox. This avoided the complexity of building a fan that could withstand hot, corrosive gases, but introduced a new problem. The firebox was at positive pressure, and hot gases and cinders could be blown out the firebox doors if they were opened while the blower was operating. This potentially dangerous arrangement was eventually replaced with a smokebox fan.
One of the more successful turbines operated in the United Kingdom, the LMS Turbomotive, built in 1935, [8] was a variation of the Princess Royal 4-6-2 large passenger express locomotive. There was no condenser. Although a disadvantage for thermal efficiency of the turbine, it allowed the turbine exhaust to still be used through a blastpipe to draw the fire, as for a conventional steam locomotive and avoiding the separate draught fans that caused so much trouble for other turbine locomotives. See paper by Roland Bond J. Instn Loco. Engrs., 1946, 36 (Paper 458) via Despite this limitation, it had greater thermal efficiency than conventional locomotives. The high efficiency mainly resulted from the fact that there were six steam nozzles directed into the turbine which could be turned on and off individually. Each nozzle could thus be allowed to operate, or not, at full power, rather than being inefficiently throttled to a lower pressure. A certain amount of inspiration appears to have come from Fredrik Ljungström's turbines in Sweden.
The main turbine failed after eleven years in heavy service. The Turbomotive was converted to piston drive in 1952, renamed "Princess Anne" and shortly after entering service was withdrawn following the deadly Harrow and Wealdstone rail crash in 1952.
Another locomotive was built by Beyer, Peacock and Company, using the Ljungström turbine by Fredrik Ljungström. Like one of Ljungström's early designs, the driving wheels were under the tender. Performance was disappointing, however, partly because of poor heating of the boiler.
The Reid-Ramsey locomotive (described below) was rebuilt by the North British Locomotive Company, replacing its electrical transmission with a direct drive from the turbine. Only a few tests were done before it was abandoned due to mechanical failures.
In the waning years of steam, the Baldwin Locomotive Works undertook several attempts at alternative technologies to diesel power. In 1944, Baldwin built the sole example of the S2 class for the Pennsylvania Railroad, delivering it in September 1944. It was the largest direct-drive steam turbine locomotive in the world and had a 6-8-6 wheel arrangement. It was originally designed as a 4-8-4, but due to shortages of lightweight materials during World War II, the S2 required additional leading and trailing wheels. Numbered 6200 on the PRR roster, the S2 had a maximum power output of 6,900 HP (5.1 MW) and was capable of speeds over 100 mph (160 km/h). With the tender, the unit was approximately 123 feet (37 m) long. The steam turbine was a modified marine unit. While the gearing system was simpler than a generator, it had a fatal flaw: the turbine was inefficient at slow speeds. Below about 40 mph (64 km/h) the turbine used enormous amounts of steam and fuel. At high speeds, however, the S2 could propel heavy trains almost effortlessly and efficiently. The smooth turbine drive put far less stress on the track than a normal piston-driven locomotive. However, poor efficiency at slow speeds doomed this turbine, and with diesel-electrics being introduced, no more S2s were built. The locomotive was retired in 1949 and scrapped in May, 1952.
The Reid-Ramsey turbine, built by the North British Locomotive Company in 1910, had a 2-B+B-2 (4-4-0+0-4-4) wheel arrangement. Steam was generated in a standard locomotive boiler, with superheater, and passed to a turbine generator. Exhaust steam was condensed and recirculated by small auxiliary turbine pumps. [9] The armatures of the motors were mounted directly on the four driving axles. It was later rebuilt as a direct-drive turbine locomotive as noted above.
The Armstrong Whitworth turbine, built in 1922 (image right), had a 1-C+C-1 (2-6-6-2) wheel arrangement. It was fitted with a rotary evaporative condenser, in which the steam was condensed by passing it through a rotating set of tubes. The tubes were dampened and cooled by the evaporation of water. The loss of water from evaporation was far less than what it would have been with no condenser at all. The airflow in the condenser had to take a convoluted path, reducing the condenser's efficiency. The locomotive was overweight and a poor performer. It was returned in 1923 and scrapped.
General Electric built two steam turbine-electric locomotives with a 2+C-C+2 (4-6-6-4) wheel arrangement for the Union Pacific in 1938. These locomotives essentially operated as mobile steam power plants and were correspondingly complex. They were the only condensing steam locomotives ever used in the United States. A Babcock & Wilcox boiler provided steam, which drove a pair of steam turbines which powered a generator, providing power to the electric traction motors that drove the wheels, as well as providing head-end power for the rest of the train. Boiler control was largely automatic, and the two locomotives could be connected together into a multiple unit , both controlled from a single cab. The boiler was oil-fired, and the fuel was "Bunker C" heavy fuel oil, the same fuel used in large vessels, and also the fuel which was later used in Union Pacific's gas turbine-electric locomotives. Union Pacific accepted the locomotives in 1939, but returned them later that year, citing unsatisfactory results. The GE turbines were used during a motive power shortage on the Great Northern Railway in 1943, and appear to have performed quite well. However, by the end of 1943, the wheels of both locomotives were worn to the point of needing replacement, and one of the locomotive's boilers developed a defect. The locomotives were returned to GE and dismantled. [10]
In 1947–1948 Baldwin built three unusual coal-fired steam turbine-electric locomotives for passenger trains on the Chesapeake & Ohio Railway (C&O). Their designation was M1, but because of their expense and poor performance they acquired the nickname "Sacred Cow". The 6,000 horsepower (4,500 kW) units, which had Westinghouse electrical systems, had a 2-C1+2-C1-B wheel arrangement. They were 106 feet (32 m) long. The cab was in the center with a coal bunker ahead and a conventional boiler behind it, with the tender only carrying water. [11] These locomotives were intended for a route from Washington, D.C. to Cincinnati, Ohio but could never travel the whole route without some sort of failure. Coal dust and water frequently got into the traction motors. While these problems could have been fixed given time, it was obvious that these locomotives would always be expensive to maintain and all three were scrapped in 1950.
In May 1954 Baldwin built a 4,500 horsepower (3,400 kW) steam turbine-electric locomotive for freight service on the Norfolk & Western Railway (N&W), nicknamed the Jawn Henry after the legend of John Henry, a rock driller who famously raced against a steam drill and won, only to die immediately after. Length including tenders was 161 ft 1-1/2 inches, probably the record for a steam locomotive; engine-only length was 111 ft 7-1/2 inches, perhaps the record for any single unit. [12] [13]
The unit looked similar to the C&O turbines but differed mechanically; it was a C+C-C+C with a Babcock & Wilcox water-tube boiler with automatic controls. The boiler controls were sometimes problematic, and (as with the C&O turbines) coal dust and water got into the motors. The Jawn Henry was retired from the N&W roster on January 4, 1958.
A locomotive or engine is a rail transport vehicle that provides the motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, motor coach, railcar or power car; the use of these self-propelled vehicles is increasingly common for passenger trains, but rare for freight trains.
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.
A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,700 times. Functionally, it is a steam engine on wheels.
A tender or coal-car is a special rail vehicle hauled by a steam locomotive containing its fuel and water. Steam locomotives consume large quantities of water compared to the quantity of fuel, so their tenders are necessary to keep them running over long distances. A locomotive that pulls a tender is called a tender locomotive. Locomotives that do not have tenders and carry all their fuel and water on board the locomotive itself are called tank locomotives or tank engines.
The London, Midland and Scottish Railway (LMS) Princess Royal Class is a class of express passenger 4-6-2 steam locomotive designed by William Stanier. Twelve examples were built at Crewe Works, between 1933 and 1935, for use on the West Coast Main Line. Two are preserved.
Steam power developed slowly over a period of several hundred years, progressing through expensive and fairly limited devices in the early 17th century, to useful pumps for mining in 1700, and then to Watt's improved steam engine designs in the late 18th century. It is these later designs, introduced just when the need for practical power was growing due to the Industrial Revolution, that truly made steam power commonplace.
Main components found on a typical steam locomotive include:
The Pennsylvania Railroad's S2 class was a steam turbine locomotive designed and built in a collaborative effort by Baldwin Locomotive Works and Westinghouse Electric & Manufacturing Company, as an attempt to prolong the dominance of the steam locomotive by adapting technology that had been widely accepted in the marine industry. One was built, #6200, delivered in September 1944. The S2 was the sole example of the 6-8-6 wheel arrangement in the Whyte notation, with a six-wheel leading truck, eight driving wheels, and a six-wheel trailing truck. The S2 used a direct-drive steam turbine provided by the Westinghouse Electric & Manufacturing Company, geared to the center pair of axles with the outer two axles connected by side rods; the fixed gear ratio was 18.5:1. Such design was to prevent energy loss and S2 achieved a mechanical efficiency of 97% which means only 3% of steam energy was lost within the propulsion equipment. The disadvantage of a direct-drive steam turbine was that the turbine could not operate at optimal speeds over the locomotive's entire speed range. The S2 was the largest, heaviest and fastest direct-drive turbine locomotive design ever built.
A jackshaft is an intermediate shaft used to transfer power from a powered shaft such as the output shaft of an engine or motor to driven shafts such as the drive axles of a locomotive. As applied to railroad locomotives in the 19th and 20th centuries, jackshafts were typically in line with the drive axles of locomotives and connected to them by side rods. In general, each drive axle on a locomotive is free to move about one inch (2.5 cm) vertically relative to the frame, with the locomotive weight carried on springs. This means that if the engine, motor or transmission is rigidly attached to the locomotive frame, it cannot be rigidly connected to the axle. This problem can be solved by mounting the jackshaft on unsprung bearings and using side-rods or chain drives.
A condensing steam locomotive is a type of locomotive designed to recover exhaust steam, either in order to improve range between taking on boiler water, or to reduce emission of steam inside enclosed spaces. The apparatus takes the exhaust steam that would normally be used to produce a draft for the firebox, and routes it through a heat exchanger, into the boiler water tanks. Installations vary depending on the purpose, design and the type of locomotive to which it is fitted. It differs from the usual closed cycle condensing steam engine, in that the function of the condenser is primarily either to recover water, or to avoid excessive emissions to the atmosphere, rather than maintaining a vacuum to improve both efficiency and power.
A triplex Mallet locomotive is a steam locomotive that divides the driving force on its wheels by using three pairs of cylinders to drive three sets of driving wheels. Any such locomotive will inevitably be articulated. All triplex locomotives built were of the Mallet type, but with an extra set of driving wheels under the tender. The concept was extended to locomotives with four, five or six sets of drive wheels. However, these locomotives were never built, except for one quadruplex locomotive in Belgium.
Fredrik Ljungström was a Swedish engineer, technical designer, and industrialist.
The South African Railways Class 25 4-8-4 of 1953 was a condensing steam locomotive.
The South African Railways Class 19D 4-8-2 of 1937 was a steam locomotive.
The South African Railways Class MA 2-6-6-0 of 1909 was a steam locomotive from the pre-Union era in the Natal Colony.
The South African Railways Class MD 2-6-6-2 of 1910 was a steam locomotive from the pre-Union era in Transvaal.
The South African Railways Class MG 2-6-6-2 of 1911 was a steam locomotive from the pre-Union era in Transvaal.
The South African Railways Class GM 4-8-2+2-8-4 of 1938 was an articulated steam locomotive.
A steam motor is a form of steam engine used for light locomotives and light self-propelled motor cars used on railways. The origins of steam motor cars for railways go back to at least the 1850s, if not earlier, as experimental economizations for railways or railroads with marginal budgets. These first examples, at least in North America, appear to have been fitted with light reciprocating engines, and either direct or geared drives, or geared-endless chain drives. Most incorporated a passenger carrying coach attached to the engine and its boiler. Boiler types varied in these earlier examples, with vertical boilers dominant in the first decade and then with very small diameter horizontal boilers. Other examples of steam motor cars incorporated an express-baggage or luggage type car body, with coupling apparatus provided to allow the steam motor car to draw a light passenger coach.
A compound engine is an engine that has more than one stage for recovering energy from the same working fluid, with the exhaust from the first stage passing through the second stage, and in some cases then on to another subsequent stage or even stages. Originally invented as a means of making steam engines more efficient, the compounding of engines by use of several stages has also been used on internal combustion engines and continues to have niche markets there.
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