Composite steam locomotive
A compound steam locomotive has a steam engine with dual use of steam expansion in separate cylinders , which is referred to as compound action . A composite steam locomotive has at least two cylinders, and more advanced designs have two pairs of cylinders.
Operational characteristics
In the first cylinder, the high-pressure cylinder with a smaller diameter, part of the heat gradient of the steam is converted into work by expansion and piston movement . The steam escaping after the expansion is directed into an intermediate container (sensor or receiver), which releases the steam to the low-pressure cylinder. If the crank offset angles between the drive wheel rods of the high and low pressure cylinders are 90 °, the transducer must have a fairly large capacity in order to avoid back pressure on the high pressure piston. If, on the other hand, the movements of the high-pressure and low-pressure pistons are the same or exactly opposite, a simple steam pipe is sufficient instead of the intermediate container. By using the steam expansion in two steam cylinders one behind the other, substantial savings are achieved. The efficient use of the composite effect is linked to a high vapor pressure, the application at boiler pressures of less than 13 atm. Overpressure seems inappropriate.
For operation with wet steam from 12 to 16 atm. Pressure was found to reduce steam consumption by 15 to 25% and fuel consumption to the same extent. When compared with a locomotive with simple steam expansion, the increase in profitability is often even greater, since the less stressed boiler of the composite locomotive has a better degree of efficiency. On locomotives with highly superheated steam, however, the gain due to the composite effect is less pronounced, since the cooling losses in the steam cylinder are less noticeable with superheated steam. The profit from the composite effect is limited to 10 to 15% on superheated steam locomotives.
Special start-up devices enable live steam to be fed into all cylinders at the highest pressure in order to achieve the greatest possible pulling force at the start of a journey or at low speeds.
The main disadvantages of composite steam locomotives are that starting up requires special equipment and that, due to their weak points, the maximum cylinder pulling force is lower than with comparable twin locomotives. The optimal distribution of the work to both cylinders is only possible under certain operating conditions. However, in operation it has been shown that even severe irregularities on two-cylinder compound locomotives do not have any significant disadvantages. Four-cylinder compound locomotives are even less sensitive in this regard.
An undesirable consequence of the large volume of the cylinder space in the low-pressure cylinders is the greater resistance to running when idling, which is particularly important in fast-moving locomotives. Effective methods of reducing the otherwise considerable air pumping work must be used here.
Since the benefits of composite effect are limited, successful four-cylinder composite locomotives are much more difficult to design than locomotives with single steam expansion. This fact has not always been taken into account for an all-round satisfactory construction.
Development history
Anatole Mallet carried out the first tests on steam locomotives with the composite technology already introduced in stationary steam engines from 1876 . He equipped a two-cylinder locomotive for the Biarritz-Bayonne railway with a high-pressure and a low-pressure cylinder, in which the steam expansion took place one after the other. This vehicle achieved a fuel saving of 25% compared to locomotives with simple steam expansion.
In 1880, the Prussian State Railways first used a T 0 twin-cylinder compound steam locomotive designed by August von Borries . In England in 1879 Francis William Webb built a three-cylinder compound locomotive on the London and North Western Railway with two high-pressure cylinders and one low-pressure cylinder, each of which powered a special, uncoupled axle, which, however, was unsuccessful. A three-cylinder and three-coupled compound locomotive, the StEG II 581 , built in Austria in 1892 , was also not a convincing success.
Around 1876, Alfred de Glehn in France investigated the possibilities of the composite effect for use on steam locomotives. This resulted in the first four-cylinder compound locomotive North No. 701, developed together with Gaston du Bousquet in 1886, with two high-pressure cylinders for the rear drive wheel set and two low-pressure cylinders for driving the front drive wheel set. The locomotives of the 2'B-1 '- "Atlantic" type with four cylinders, built in series for the French Chemins de fer du Nord from 1890 onwards, proved to be very successful, and their design principle was adopted by many other railway companies. The Prussian State Railways ordered 79 machines of this type, which were classified as the Prussian S 7 class.
In southern Germany, the compound steam locomotive was introduced in Baden by Courtin, in Bavaria by Joseph Anton von Maffei , in Saxony by Lindner, in Württemberg by Kittel. In Prussia, after initially extensive procurement and use of compound locomotives, the compound principle is almost completely abandoned, as hot steam and the superheater have meanwhile been used.
In contrast, more sophisticated developments as well as high fuel costs in France, southern Germany, Austria and Switzerland lead to further preference for the composite principle, also with superheated steam, in order to achieve the highest possible increase in the profitability of the locomotive. In 1908 a. a. Karl Gölsdorf for maintaining the composite effect. This is followed by numerous superheated steam composite locomotives on the Austrian state railways. Some of them are powerful mountain locomotives with five and six coupled axles. In Russia, Alexander Borodin and Albert Czeczott ensured that the composite principle was applied.
In England, a "Class 3CC" machine on the North Eastern Railway was successfully converted into a three-cylinder compound locomotive by Walter Mackersie Smith (1842–1906) in 1898 . Based on this model, five 2'B n3v machines as Class 1000 were designed by Samuel W. Johnson at the Midland Railway . Of these, Richard Deeley (1855–1944) built another 45 of a more powerful type and from 1914 these were equipped with a superheater for superheated steam operation. Starting in 1924, a total of 195 composite machines of almost identical type were delivered by several English locomotive factories for the London, Midland and Scottish Railway .
The high points of the performance development of compound locomotives were reached in the 1940s with the huge mallet types in North America, as well as in Europe with the "reconstructions" of individual locomotives carried out by André Chapelon . In France in 1943, André Chapelon converted the former 2'D1 'h3 locomotive 241-101 of the Compagnie des chemins de fer de l'État into the 2'D2' h3v type SNCF 242 A 1 , which was equipped with a indexed power of 3900 kW is considered to be the most powerful steam locomotive ever built in Europe.
Significant variants
De Glehn design
In the de Glehn (1890) design, one pair of pistons drives the first, the other the second drive axis , so the work is distributed over two axes. The main external feature of the de Glehn design were the high-pressure cylinders for the second drive axle that were attached to the outside of the frame and relatively far back. The two low-pressure cylinders for driving the first drive axle were located further forward within the frame. Above all, this division should enable the axes to move laterally in relation to each other when cornering. With the first version, the mechanical coupling of the drive wheel sets, which are to a certain extent " single-axle drive ", was dispensed with by means of coupling rods. However, since the locomotive tended to skid, the following constructions received the usual coupling rods again .
A special operating feature are the completely separate controls for the high and low pressure cylinders, which can be set individually by the locomotive driver with special reversals. This has the advantage of using the most advantageous fillings in both cylinder groups, which are dependent on the degree of stress and the driving speed. The starting device associated with the design has a switching cylinder operated from the driver's cab; in addition, throttled live steam can be let into the low-pressure valve boxes through thin pipelines. This results in four different operating states:
- Composite effect as a rule for the steady state;
- Quadruple effect with live steam in all four cylinders for start-up;
- Twin effect of the high pressure cylinders alone;
- Twin effect of the low pressure cylinder alone.
The last two circuits were only considered in the event of damage to one of the two expansion stages. A similar starting device from Borsig uses changeover cocks in place of the rotary valve; the live steam supply to the low-pressure slide valve is inevitably opened when the cocks are set to high-pressure exhaust.
The design of numerous other German, French and other steam locomotives can be traced back to de Glehn: for example the Baden locomotives of type IV e , the Bavarian CV , the locomotives of the Reichseisenbahnen in Alsace-Lorraine S 12 , S 5 and T 17 , the Prussian locomotives of Genera P 7 , S 10 , S 5 and S 7 , the Saxon X V , the Württemberg classes D and F 1c , as well as the GDR conversions of former French locomotives DR 07 1001 and DR 08 1001 . The locomotives on the Jura – Simplon Railway A 3/5 were also “de Glehn” machines.
Borries type
De Glehn locomotives with individually controllable cylinders require the locomotive driver to be particularly familiar with these special characteristics and require more attention to machine operation than to route monitoring. In addition, with this operational design, there is a large number of parts in the controls on an already complex structure of four-cylinder locomotives. These were reasons why the de Glehn type was not consistently used as the only type of compound locomotive. For example, in the four-cylinder locomotive developed by August von Borries in 1897 , the controls of both cylinder groups were combined in such a way that only two external control rods are available. All four pistons act on the crankshaft of the first drive axle, the inner and outer crank webs of which are directed in opposite directions, so that the pistons work in opposite directions, the acceleration forces of the engine masses largely balance each other out and therefore no longer require counterweights. For this purpose, von Borries improved the starting devices and also created the theoretical basis for an appropriate calculation of the cylinder dimensions and the controls.
In Germany, the Prussian locomotive types S 5 and S 7 , which were already available as the “de Glehn” type, were also designed as the “von Borries” type, in the case of the S7 with 159 units, twice as many as the “de Glehns”. The Badische IV f and the Palatinate P 4 were also "von Borries" types with 35 and 11 copies respectively.
Mallet and Meyer types
In bogie locomotives of the Mallet type , the compound effect is advantageously used in such a way that one frame carries the high-pressure cylinder, the other the low-pressure cylinder. The leading movable bogie frame is coupled to the main frame like a drawbar. The latter also carries the boiler, which rests on the bogie at the front and is movable. The main frame is driven by the high pressure cylinders, the front bogie by the low pressure cylinders. Since the boiler is firmly connected to the main frame, there are no movable steam pipes that are difficult to seal. The relatively long steam pipe between the high and low pressure cylinders can be made sufficiently flexible for the not very large deflection angle. The exhaust steam from the low-pressure cylinders is guided through movable pipes to the blower pipe in the boiler smoke chamber. The controls of both racks are operated simultaneously.
With the Meyer type , both bogies are movable, so that the advantage of fixed high-pressure steam pipes is eliminated.
Vauclain type
With this type of construction, which is particularly widespread in the USA, one high-pressure and one low-pressure cylinder were combined into one casting on each side of the locomotive. The two piston rods worked on a common crosshead . The advantage of this type of construction was the good accessibility and that it managed without the use of goiter shafts. The main disadvantage was the poor mass balance, as the acceleration forces of the high and low pressure pistons could not balance each other.
Tandem compound locomotives
Based on the successful land and ship steam engines developed by Arthur Woolf, attempts with tandem compound locomotives went back to the year 1868. Tandem steam engines had high and low pressure cylinders arranged one behind the other, which either acted on a common crosshead or a continuous piston rod. The first such locomotives ran in Europe on British routes. There were three experimental machines from 1885 and 1886 with internal engines. Some 2`C tank locomotives were running in France from 1902 and Hungary used 2`B tandem locomotives from 1890. With 93 Ie purchased , they remained the most successful tandem compound locomotives. The Russian П series with 169 and the Russian Р series with 477 units were produced more numerically . This design was also tried in the USA without it being able to gain acceptance. With their construction, a composite effect could be achieved without having to use a bolster axis . The main reason for their lack of acceptance was the unwieldy repair of the vehicles.
Three-cylinder composite steam locomotives
While Webb's attempt at a three-cylinder compound locomotive mentioned above did not prove successful, later designs with a centrally located high-pressure cylinder and two low-pressure cylinders were carried out several times, particularly on English railways, with great success in some cases. Peak of development was resulting from a conversion French 2'D2 'H3V -Schnellzuglok SNCF 242 A 1 with three-cylinder compound engine, which is an indexed peak capacity of 5,300 PSI and 3,900 kW reached.
The working points of the two low-pressure cylinders of the 242 A 1 were offset from one another by 90 ° during one drive wheel revolution, the working point of the central high-pressure cylinder is indicated with an offset of 135 ° in the center of the two 90 ° working points opposite. An intermediate container was available to receive and distribute the low-pressure steam of 14 bar from the high-pressure cylinder fed with 20 bar to the low-pressure cylinders.
An individual valve control made it possible to supply all three cylinders with live steam of 14 bar at the same time with simple steam expansion. At a speed of around 25 km / h, the low-pressure regulator was closed and the high-pressure regulator opened, and the machine then ran in regular interconnected operation.
This drive configuration was not very popular with the German railway administrations. Only the Royal Württemberg State Railways maintained two series with a three-cylinder compound engine, with their classes E (passenger train locomotives , produced by Cockerill in Seraing in Belgium) and G (freight locomotives from the Esslingen machine factory, chief designer Emil Kessler), and only those were valid Freight locomotives with the nickname "Württemberg Elephants" as a successful design.
In 1902 the Prussian T 6 with two-axle drive, designed by Gustav Wittfeld , was built for the Berlin Stadtbahn ; the inner cylinder acted on the first drive axle and the outer cylinder on the second. It did not prove itself, and only its external design deserves praise.
Two test machines with the 2'B2 'wheel arrangement by the designers Wittfeld and Kuhn were built by the Henschel company in 1904 and classified as the Prussian S 9 Altona 561 and Altona 562 , they turned out to be a faulty design and were scrapped around 1918.
literature
- Brückmann: Contribution to the history of the composite locomotive. Organ 1890, p. 294 and 1891, p. 192; The composite locomotive in North America. Ztschr.Dt. Ing. 1894, p. 1213.
- Sanzin: The composite locomotive in England. Negotiating des Gewerbefleißes 1896, p. 91.
- Ludwig Troske : General railway knowledge. Part II, p. 222.
- Guillery-Stockert: Handbook of Railway Engineering . Vol. I, p. 251.
- Gölsdorf: starting device. Organ 1894.
- Kühl: New efforts in locomotive construction.
- Mallet: Étude sur les locomotives de montagne. Mémoires de la société des ingénieurs civiles. August 1912.
- Erich Metzeltin : The new Prussian compound locomotives. Ztschr. Dt. Ing. 1909, p. 641.
- Dawner: Four-cylinder compound superheated steam locomotives for the Württemberg State Railways. Ztschr. Dt. Ing. 1909, p. 2069. [⇐88]
- SR Wood, David P. Morgan: The thrifty compound . In: Trains . Kalmbach Publishing Co., September 1951, ISSN 0041-0934 , p. 4448-Y .
Web links
Individual evidence
- ↑ a b c d Roell: Encyclopedia of the Railway System. Berlin, Vienna 1912
- ↑ Explanation of the construction in Spanish under "Tracción repartida" ( Memento of the original from May 10, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ The Locomotive 1906, no. 5, p. 78, fig. 8
- ↑ The Locomotive 1904, no. 5, p. 103
- ^ French Compound Locomotives, 242 A 1
- ↑ Maedel, K.-E .: "The German steam locomotives yesterday and today", 4th edition, Berlin 1966, p. 184
- ↑ Maedel, K.-E .: "The German steam locomotives yesterday and today", 4th edition, Berlin 1966, p. 148
