The reference for locomotives and railcars
Saxon XV HTV
German Reichsbahn class 79
Germany | 1916 | 2 produced
Eisenbahnstiftung Joachim Schmidt

Since the Saxon state railways in the Ore Mountains had steep routes, the increased weight of the trains in the years before the First World War meant that a powerful tank locomotive had to be developed to push or pull freight trains. The result was the XV HTV with an unusual and complex design of the chassis, which was only built twice.

Since people in Saxony were not convinced of the suitability for everyday use of the Gölsdorff design with six coupled axles, a different path was taken in the development. Two three-axle bogies were used, but they were not mounted on bogies, but firmly in the frame. Each inner axle could be shifted sideways by 28 mm, while the outer axles were designed as Klien-Lindner hollow axles and could be radially deflected by up to 37 mm. The latter were mounted in outer frames, which gave the locomotive an unusual appearance.

A cylinder block was located in the center of the locomotive on each side, in which a high-pressure cylinder drove the rear chassis and a low-pressure cylinder drove the front chassis. This resulted in a short distance between the cylinders, but a long way for the steam to travel from the boiler to the cylinder blocks and back to the blastpipe. This construction proved to be very successful in terms of running characteristics in curves and wear, but required a great deal of maintenance. In addition, the frequent slipping of the wheels resulted in different levels of wear on the wheel tires of the two engines. As a result, the synchronization of the high and low pressure cylinders was quickly lost, so that frequent readjustment of the control was necessary.

Despite this, the two units did their job reliably, with the smooth running being particularly noticeable and with a top speed of 70 km/h they were relatively fast for freight trains. They were taken over by the Reichsbahn and given the numbers 79 001 and 79 002. However, their service life ended in 1932, since such maintenance-intensive locomotives could not be used economically in this small number.

Axle config0-6-6-0T (Duplex) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length48 ft 1 3/16 in
Wheelbase36 ft 5 in
Fixed wheelbase24 ft 7 1/4 in
Empty weight164,465 lbs
Service weight203,266 lbs
Adhesive weight203,266 lbs
Axle load34,061 lbs
Water capacity2,245 us gal
Fuel capacity4,850 lbs (coal)
Power sourcesteam
Estimated power872 hp (650 kW)
Optimal speed16 mph
Top speed43 mph
Starting effort35,211 lbf
with start valve42,253 lbf
Power Plant
Driver diameter55.1 in
Boiler pressure218 psi
Expansion typecompound
Cylindersfour, HP: 17 5/16 x 24 13/16 in
and LP: 26 3/4 x 24 13/16 in
Grate area26.9 sq ft
Firebox area121.5 sq ft
Tube heating area1,247.6 sq ft
Evaporative heating area1,369.2 sq ft
Superheater area440.2 sq ft
Total heating area1,809.4 sq ft
Calculated Values
steam locomotive
tank locomotive
double cylinders compound
last changed: 04/2022

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