Compound locomotive
A composite steam locomotive has a steam engine with dual use of the vapor expansion in separate cylinders, which is referred to as a composite effect. A compound steam locomotive has therefore at least two cylinders, advanced designs had two pairs of cylinders.
Operating characteristics
In the first cylinder, the high-pressure cylinder having a smaller diameter, a portion of the thermal gradient of the steam is realized by expansion and reciprocating movement in the work. The exiting steam after expansion is introduced into an intermediate vessel ( receiver or receiver) that delivers the vapor to the low pressure cylinder. Amount to the crank angle of offset between the Treibradgestängen of the high - and low-pressure cylinder 90 ° to the transducer must have a fairly large capacity to avoid a back pressure on the high pressure piston. The movements of the high-pressure and low-pressure piston on the other hand exactly the same or in opposite directions, it is sufficient, instead of the intermediate container a simple steam pipe. By taking advantage of the steam expansion in two steam cylinders consecutively significant savings can be achieved. The efficient utilization of the composite effect is tied to a high vapor pressure, the application for tank pressures of less than 13 atm. Pressure does not seem appropriate.
For use with wet steam 12 to 16 atm. Pressure, a reduction of the steam consumption of 15 to 25% and found to the same degree, a reduced fuel consumption. For comparison with a locomotive with a simple steam expansion to increase the cost-effectiveness is often even greater, because the less stressed the compound locomotive boiler has a better efficiency. On locomotives with highly superheated steam of the gain by the composite effect, however, is less pronounced, as do the cooling losses in the steam cylinder for hot steam less noticeable. The win by the composite action is limited to hot steam locomotives to 10 to 15%.
Special Anfahrvorrichtungen allow to pass live steam at the highest pressure in all cylinders to achieve the maximum tractive effort at start or low speeds.
The main disadvantages of the compound steam locomotives are considered that the start-up requires special facilities, and that by their weak points, the maximum cylinder tractive force is lower than comparable twin locomotives. The optimal distribution of work on both cylinders is only possible under certain operating conditions. However, it has been shown in operation that even stronger irregularities remain at two-cylinder compound locomotives without significant drawbacks. Four-cylinder compound locomotives are even less sensitive in this respect.
An undesirable consequence of the large cylinder chamber contents of the low-pressure cylinder is the larger running resistance at idle, which will work in particular in fast-moving locomotives. Here effective methods must be used to reduce the otherwise considerable air pumping work.
Since the impact of the benefits of composite action only within certain limits, the design of successful four-cylinder compound locomotives is much more difficult than steam locomotives with simple stretching. This fact has not always been observed for a mutually satisfactory construction.
History of development
First attempts at steam locomotives with the already introduced for stationary steam engines composite technology led by Anatole Mallet in 1876. He equipped a two-cylinder locomotive for the railroad Biarritz -Bayonne with a high and a low pressure cylinders in which the steam expansion took place one after another. This vehicle achieved a fuel saving of 25 % compared to locomotives with simple steam expansion during operation.
1880 was the first time in the Prussian state railways is designed by August von Borries two-cylinder compound steam locomotive T 0 are used. In England in 1879 Francis William Webb built on the London and North Western Railway, a three-cylinder compound locomotive with two high-pressure cylinders and a low-pressure cylinders, each of which drives a special uncoupled axis, but had no success. One built in Austria in 1892 three-cylinder and six-coupled compound locomotive, the StEG II 581, was also granted no convincing success.
Year 1876 examined Alfred de Glehn in France the possibilities of composite action for use on steam locomotives. This resulted in 1886 developed together with Gaston du Bousquet first four-cylinder compound engine No. 701 North with two high-pressure cylinders for the rear Antriebsradsatz and two low-pressure cylinders for driving the front Treibradsatzes. The with this principle in 1890 for the French Chemins de fer du Nord series-built locomotives 2'B -1 ' - "Atlantic" type with four cylinders proved to be very successful, and their principle of construction has been adopted by many other railway companies. The Prussian State Railways ordered 79 machines of this type which were classified as class Prussian S 7 in the stock.
In southern Germany, the compound steam locomotive in Baden by Courtin, in Bavaria by Joseph Anton von Maffei, in Saxony by Lindner, in Württemberg introduced by Kittel. In Prussia, the composite principle abandoned after initially extended procurement and use of composite locomotives almost completely again because now hot steam and superheater were used.
More sophisticated developments as well as high fuel costs lead the other hand, in France, southern Germany, Austria and Switzerland to further favor the composite principle with hot steam to achieve the highest possible increase in the cost of the locomotive. So stepped et al 1908 Karl Gölsdorf for the retention of a composite action. It follow from the Austrian State Railways numerous steam locomotives composite, which in part powerful mountain locomotives with five and six axes are coupled.
In England in 1898 was the successful conversion of a "Class 3CC " machine of the North Eastern Railway for three-cylinder compound locomotive by Walter Mackersie Smith ( 1842-1906 ). Following this example, five 2'B N3V machines were designed as Class 1000 by Samuel W. Johnson at the Midland Railway. Of which under Richard Deeley (1855-1944) for an additional 45 pieces of a stronger type were built and these fitted from 1914 with a superheater for steam operation. In 1924 a total of 195 composite machines of almost identical type supplied by several English locomotive factories for the London, Midland and Scottish Railway.
Highlights of the performance development of composite locomotives were in the 1940s reached with the giant mallet types in North America and in Europe, the results of André Chapelon " reconstructions " of individual locomotives. Thus took place in 1943 in France, the single-piece conversion of the former 2'D1 ' h3 locomotive 241-101 of the Compagnie des chemins de fer de l' État for 2'D2 ' h3v -Type SNCF 242 A 1 by André Chapelon, with a indicated power output of 3900 kW as the strongest ever built in Europe steam locomotive applies.
Significant variations
Type de Glehn
In the design de Glehn (1890), a piston drives the first pair, the other the second driving axle, the work is thus divided into two axes. The outer main feature of the design de Glehn were the outside of the frame and relatively far rear-mounted high-pressure cylinders for the second driving axle. The two low-pressure cylinder for the drive of the first driving axle lying further forward within the frame. This division should in particular allow a lateral movement of the axes in the curve running against each other. The first version was sacrifice the mechanical coupling of a certain extent with " Einzelachsantrieb " drive axles provided by coupling rods. However, since the locomotive tended to spin, the following structures were again the usual coupling rods.
A special feature is the operating completely separate controllers for high - and the low-pressure cylinder, which can be set individually by the locomotive engineer with special reversals. This has the advantage that in each case apply the most advantageous fillings in the two cylinder groups, and the degree of stress on the driving velocity. The starting device associated with the type has one of the driver's cab -operated shift cylinders, also can be embedded into the low pressure valve boxes by thin pipes throttled steam. This leads to four different Bert actuator states:
The last two circuits were considered only for emergency damage one of the two expansion stages .. A similar starting device of Borsig used in place of the rotary slide cocks; the live steam feed to the low-pressure valves is this necessarily opens in position of taps on the high-pressure exhaust.
The design and construction of numerous other German, French and other steam locomotives is to de Glehn returned: so the Baden locomotives of Class IV e, the Bavarian CV, the locomotives of the Imperial Railways in Alsace-Lorraine S 12, S 5 and T 17, the Prussian locomotives 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 former French locomotives DR 07 and DR 08 1001 1001. the locomotives of the Jura -Simplon Lane A 3/5 were " de - Glehn " machines.
Type of Borries
Locomotives to de Glehn with individually controllable cylinders presuppose a special closeness of the engine driver with these specific characteristics and captured the attention of the pure machine operation in relation to the distance observation to a greater degree to complete. In addition, in this operation a large multipartite interpretation of the controls on an already complex nature of four-cylinder engines. These were the reasons that the type de Glehn not consistently found as the only type of compound locomotive use. So in 1897 by August von Borries developed four cylinder loco controls both cylinder groups became so merged that only two external control rods are available. All four pistons act while on the crankshaft of the first driving axle, the inner and outer crank arms are opposite, so that the pistons are working in opposite direction to compensate the acceleration forces the engine masses thereby largely and therefore do not require balancing by counterweights more. Von Borries to improved Anfahrvorrichtungen and also created the theoretical basis for an appropriate calculation of the cylinder dimensions and the controls.
In Germany, the existing than " de Glehn " -type Prussian locomotive classes were S 5 and S 7 are designed as " von Borries " type, in the case of S7 with 159 pieces in a double number as the " de Glehns ". The Baden IV f and the Palatine P 4 were also " von Borries " types with 35 or 11 copies built.
Types Mallet and Meyer
Bogie for locomotives Mallet, the composite effect is used to advantage in such a way that the one frame, the high-pressure and the other carries the low pressure cylinder. The leading bogie frame is moveable tiller- like coupled to the main frame. The latter also carries the boiler, which rests on the front moveable bogie. The main frame is driven by the high pressure, the front bogie of the low-pressure cylinders. Since the boiler with the main frame is fixed, account for the difficult to seal, vapor pipes here. The relatively long steam pipe between the high - and the low-pressure cylinders can be made sufficiently portable for the not very large deflection angle. The exhaust steam from the low pressure cylinder is performed by moving pipes to blow pipe into the boiler smoke box. The controls of both racks are operated simultaneously.
In the design Meyer Both trucks are mobile, so the advantage of the solid high-pressure steam pipes is eliminated.
Type Vauclain
In this spread, especially in the United States each type of the locomotive a high and a low pressure cylinders were combined to form a casting on each side. The two piston rods working on a common crosshead. The advantage of this design was the good accessibility and that they did without the use of Kropfachswellen. The main disadvantage was the poor mass balance, as the acceleration forces of the high - and low-pressure piston could not offset each other.
Tandem compound locomotives
Based on the developed by Arthur Woolf successful land and marine steam engines, attempts went with tandem compound locomotives up back in the year 1868. Tandem steam engines had arranged one behind another high and Nierderdruckzylinder who worked on a joint cross-head or a through rod either. The first such locomotives ran in Europe on British lines. These were three test machines from the years 1885 and 1886 with internal engines. In France ran from 1902 some 2 ` C tank locomotives and Hungary continued from 1890 2` B- tandem locomotives. With 93 procured Ie they remained the most successful tandem compound locomotives. In the U.S., this design was tried without which they could prevail.
Three -cylinder compound steam locomotives
While Webb's mentioned above attempt at a three-cylinder compound locomotive did not prove successful, subsequent constructions with centrally disposed high-pressure cylinder and two low-pressure cylinders, especially on English railways were run multiple times with some great success. The highlight of this development was the resultant of a tag French 2'D2 ' h3v - express train SNCF 242 A 1 with three -cylinder compound engine, which reached an indexed peak power of 5,300 PSI or 3,900 kW.
, The operating points of the two low-pressure cylinder 242 of the A 1 were added, during a Treibradumdrehung 90 ° to each other, the operating point of the central high-pressure cylinder is provided centrally opposite with an offset of 135 ° to 90 °, the two operating points. From the bar to 20 bar high pressure cylinder fed to the low pressure cylinders was an intermediate container available for the recording and distribution of the low-pressure steam of 14.
An individual valve control made it possible to provide for starting all three cylinders simultaneously with steam of 14 bar with simple steam expansion. At a speed of 25 km / h, the low-pressure regulator was closed and the high pressure regulator, the machine then ran in the regular network operation.
In the German railway authorities this drive configuration was not very popular. Only the Royal Württemberg State Railways talked with their classes E ( passenger locomotives produced at Cockerill in Seraing in Belgium ) and G ( freight locomotives from the Maschinenfabrik Esslingen, chief designer Emil Kessler ) two series with a three -cylinder compound engine, and it also only were the freight locomotives nicknamed " Württemberg Elephants " as a successful design. Two test machines with the wheel arrangement 2'B2 ' the designers Wittfeld and Kuhn, built by Henschel and classified as Prussian S 9, turned out to be a bad design and were soon scrapped.