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Saxon XII H, HV and H1
German Reichsbahn classes 176, 177 and 178
Germany | 1906 | 55 produced
Die Lokomotive, November 1913

Around the turn of the century, class X V locomotives with a 4-4-2 wheel arrangement were developed in Saxony for use in front of express trains. Since these had too little traction in the hilly country, the XII H with a 4-6-0 wheel arrangement was developed a few years later. They were among the first Saxon locomotives to use superheated steam and were built in three different types to compare the suitability of different power plants.

The actual XII H was made in 1906 in six units and had a four-cylinder engine with simple steam expansion, which was rarely found in Germany, as it was also tested a few years later on the Prussian S 10. In line with the spirit of the times, the locomotives were built with a cone-shaped cladding on the smokebox door and a wind cutter on the front of the cab. With a maximum speed of 100 km/h it was possible to tow trains of 300 tonnes. Despite this performance, it turned out that consumption was very high due to the greater heat loss through the four cylinders. In addition, it was later realized that aerodynamic optimizations in steam locomotives only brought measurable advantages at speeds of significantly more than 100 km/h.

Die Lokomotive, November 1913

From 1908 the XII HV was developed, fitted with a four-cylinder compound engine. In order to be able to make better use of the two-stage steam expansion, the boiler pressure was increased to 15 bars. The aerodynamic optimizations of the XII H were also used on it, but they were dispensed with on the later locomotives and the fairings were later removed from the older locomotives as well. Despite the higher boiler pressure, it turned out that the XII HV had a lower output than the XII H. While the latter could move 300 tonnes at 100 km/h, the compound version only managed 270 tonnes at the same speed. However, significantly lower fuel consumption values were now achieved, which is why series production of the XII HV was started. By 1914, 42 locomotives had been built.

While production of the composite version was already underway, the XII H1 was developed in view of the positive experiences with the P 8 in Prussia. Seven of them were already being built in 1909 and they only had two large cylinders. Despite the same wheel arrangement and similar dimensions, it was structurally less related to the other two variants than to the class X H1 Atlantic locomotive developed at the same time. Thus, it had a larger boiler and had the largest grate surface of all variants, but at the same time it was the lightest.

Die Lokomotive, November 1913

The result of the two cylinders was a fuel consumption that was between that of the other two versions and running characteristics which could not keep up with locomotives with four cylinders, with significantly cheaper production and simpler maintenance. However, due to its boiler, it was considerably more powerful than its sisters and could tow up to 450 tonnes at top speed. Although there was no series production, this experience was used in the development of the later XII H2 passenger locomotives and the two-cylinder engine was used there in conjunction with smaller coupling wheels, also with the 4-6-0 wheel arrangement.

After the takeover by the Reichsbahn, the three sub-types each received the class designations 176, 177 and 178. Due to their smaller numbers, the XII H and XII H1 were retired by 1928 and 1929, respectively. The decommissioning of the XII HV began as early as 1925, but one could not do without all of them right from the start and kept the last pieces until 1936. Outside of regular operational service, a single XII H with the number 17 604 survived until 1956. It was used as a heating locomotive in Dresden-Altstadt.

Axle config4-6-0 (Ten-wheeler) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length65 ft 1 in66 ft 4 in65 ft 1 in
Wheelbase27 ft 10 5/8 in27 ft 8 11/16 in28 ft 4 9/16 in
Fixed wheelbase13 ft 5 7/16 in
Empty weight146,166 lbs149,253 lbs143,080 lbs
Service weight161,599 lbs164,244 lbs160,276 lbs
Adhesive weight108,026 lbs106,042 lbs105,160 lbs
Total weight264,554 lbs267,200 lbs263,232 lbs
Axle load36,156 lbs35,715 lbs35,053 lbs
Water capacity5,548 us gal
Fuel capacity11,023 lbs (coal)
Power sourcesteam
Estimated power1,180 hp (880 kW)
Optimal speed27 mph30 mph26 mph
Top speed62 mph
Starting effort28,333 lbf25,046 lbf28,510 lbf
with start valve30,055 lbf
Power Plant
Driver diameter74.2 in75 in74.2 in
Boiler pressure174 psi218 psi174 psi
Expansion typesimplecompoundsimple
Cylindersfour, 16 15/16 x 24 13/16 infour, HP: 16 15/16 x 24 13/16 in
and LP: 26 3/4 x 24 13/16 in
two, 24 x 24 13/16 in
Grate area29.8 sq ft29.6 sq ft30.6 sq ft
Firebox area140.3 sq ft138.2 sq ft144.5 sq ft
Tube heating area1,432.7 sq ft1,436.1 sq ft1,703.3 sq ft
Evaporative heating area1,572.9 sq ft1,574.3 sq ft1,847.7 sq ft
Superheater area471.5 sq ft441.3 sq ft507 sq ft
Total heating area2,044.4 sq ft2,015.6 sq ft2,354.7 sq ft
Calculated Values
steam locomotive
De Glehn compound
last changed: 01/2022

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