DR series 99.73-76

Class 99.73–76
Numbering:	DR: 99 731–762 from 1970: 99 1731–1762 from 1992: 099 722–735
Number:	32
Manufacturer:	Saxon machine factory , Berliner Maschinenbau AG
Year of construction (s):	1928, 1929, 1933
Type :	1'E1 'h2t
Genre :	K 57.9
Gauge :	750 mm
Length over coupling:	10,540 mm
Height:	03,570 mm
Fixed wheelbase:	04,000 mm
Total wheelbase:	07,600 mm
Smallest bef. Radius:	50
Empty mass:	44.3 t
Service mass:	56.7 t
Friction mass:	46.1 t
Top speed:	30 km / h
Indexed performance :	600 PSi, 441 kW
Starting tractive effort:	83.35 kN
Driving wheel diameter:	800 mm
Impeller diameter:	550 mm
Control type :	Heusinger
Number of cylinders:	2
Cylinder diameter:	450 mm
Piston stroke:	400 mm
Boiler overpressure:	14 bar
Number of heating pipes:	92
Number of smoke tubes:	28
Heating pipe length:	3500 mm
Grate area:	01.74 m²
Radiant heating surface:	06.70 m²
Tubular heating surface:	73.60 m²
Superheater area :	29.00 m²
Evaporation heating surface:	80.30 m²
Water supply:	05.80 m³
Fuel supply:	2.5 tons of coal
Locomotive brake:	Knorr compressed air brake, originally controlled by suction air, with additional brake
Train brake:	Körting vacuum brake initially Heberlein brake today Knorr -Druckluftbremse
Train heating:	steam
Coupling type:	Scharfenberg coupling

The locomotives of the class 99.73-76 were standard locomotives of the Deutsche Reichsbahn for the Saxon narrow-gauge railways . Together with the successor series 99.77-79 , the locomotives represent the most powerful narrow-gauge locomotives for 750 mm gauge in Germany.

history

99 757 in Oybin, 1981

Although the five-way coupled class 99.67-71 was already a very powerful locomotive for operation on the mountain routes in the Ore Mountains, there was still a need for a particularly powerful design. The newly founded Reichsbahndirektion Dresden succeeded in procuring a standard locomotive for 750 mm gauge. The standardization office of the German Locomotive Association in Berlin-Tegel developed the design for the construction.

The first series of 13 locomotives was manufactured by the Sächsische Maschinenfabrik formerly Richard Hartmann in Chemnitz . According to the delivery agreement, the Sächsische Maschinenfabrik was supposed to deliver more locomotives. Due to the bankruptcy and liquidation of the company in 1930, this order was transferred to Berliner Maschinenbau AG formerly Schwartzkopff (BMAG). In 1928 seven and in 1933 a further twelve locomotives were delivered by BMAG. The locomotives, which were ultra-modern at the time, corresponded in their design to the standard-gauge standard locomotives. The locomotives met expectations. With the leader it was now possible to transport long, narrow-gauge trains with up to 56 axles uphill.

In 1945 ten locomotives had to be given to the Soviet Union as reparations . On the other hand, there was an enormous increase in traffic on the narrow-gauge railways in the Ore Mountains due to the newly started uranium mining of SDAG Wismut . In order to remedy the resulting shortage of locomotives, a similar successor type was created from 1952 at VEB Lokomotivbau Karl Marx in Babelsberg as the 99.77-79 series .

At the end of the 1960s, the first locomotives had to be retired due to damage to the boilers. Ten locomotives received new, welded boilers and continued to be used on their regular routes. The 99 1760 was converted to main oil firing in 1992.

Together with the successor design, these locomotives are often referred to by railway fans as "Saxon VII K", although this designation is incorrect because they were no longer procured by the Saxon State Railways .

technical features

The five-way coupled locomotives had a bar frame and had running axles mounted in Bissel racks. The fixed third axle, which initially had weakened wheel flanges, serves as the driving axle. After 1945 the wheel flanges were then completely removed in order to further improve the arc stability. The second and fifth coupling axles were laterally movable. The fixed wheelbase was initially 3000 millimeters, but was later extended to 4000 millimeters. As is typical for all standard locomotives, the locomotives 99 731 to 99 750 were supplied with a piston feed pump and a Knorr surface preheater installed across the smoke chamber . The 99 751 to 99 762, on the other hand, were supplied with Friedmann exhaust steam injectors, but were later also converted to Knorr preheaters. The second boiler feed device is a suction steam jet pump . The long boiler consisted of two shots.

Because the lever brake was still in use at the time , the locomotives were also fitted with the necessary equipment with roller guides and reels ex works. The locomotive itself was equipped with a Knorr compressed air brake , which is controlled via the suction air brake for the train. When the first locomotives were delivered in 1928, it was already planned to replace the outdated funnel coupling with the Scharfenberg coupling . The first locomotives were initially given funnel couplings. These were later exchanged for the new couplings without any problems.

commitment

Play media file

99 731 with a passenger train between Bertsdorf and Jonsdorf

Initially, the locomotives were used sporadically in the Wilsdruffer network and until they were replaced by the 99.77-79 series on the Schönfeld-Wiesa-Thum-Meinersdorf and Wilischthal-Thum routes. On the steep slopes of Hainsberg – Kipsdorf , Cranzahl – Oberwiesenthal and Zittau – Oybin / Jonsdorf , the powerful machines became regular locomotives. They have also been used on the Radebeul-Ost – Radeburg route since 2002 .

In August 2020, 14 locomotives were still available, which were owned equally by the Saxon Steam Railway Company (SDG) and the Saxon-Upper Lusatian Railway Company (SOEG) , seven of which were operational.

Road no.	Construction year	Manufacturer	Factory no.	owner	Location	operational
99 731	1928	Hartmann	4678	SOEG	Zittau	Yes
99 734	1928	Hartmann	4681	SDG	Oberwiesenthal	No
99 735	1928	Hartmann	4682	SOEG	Bertsdorf	No
99 741	1928	Hartmann	4691	SDG	Oberwiesenthal	No
99 746	1929	BMAG	9535	SDG	Kipsdorf	No
99 747	1929	BMAG	9536	SDG	Oberwiesenthal	Yes
99 749	1929	BMAG	9538	SOEG	Zittau	Yes
99 750	1929	BMAG	9539	SOEG	Trixi Park, Großschönau	No, monument
99 757	1933	BMAG	10148	SOEG	Zittau	No
99 758	1933	BMAG	10149	SOEG	Zittau	Yes
99 759	1933	BMAG	10150	SDG	Knight green	No, museum locomotive
99 760	1933	BMAG	10151	SOEG	Zittau	Yes
99 761	1933	BMAG	10152	SDG	Radebeul	Yes
99 762	1933	BMAG	10153	SDG	Freital-Hainsberg	Yes

gallery

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  99 734 in Spechtritz

• 

  99 735 at Teufelsmühle

• 

  99 746 in Dippoldiswalde

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  99 758 at Teufelsmühle

literature

• Erich Preuss , Reiner Preuss : Narrow gauge railways in Saxony . transpress Verlag, Stuttgart 1998, ISBN 3-613-71079-X .
• Jürgen U. Ebel, Bernd Seiler: The class 99.73–79 - standard locomotive on a narrow track . EK-Verlag, Freiburg 1994, ISBN 3-88255-119-4 .
• Wolfram Wagner, Reiner Scheffler: The Saxon VII K. The history of the 99.73–79 series . Bufe-Fachbuchverlag, Egglham 1993, ISBN 3-922138-47-0 .

Web links

Commons : DR Series 99.73–76  - Collection of pictures, videos and audio files

Individual evidence

1. ↑ Vehicle inventory of the Zittau network on zittauer-schmalspurbahn.de
2. ↑ Vehicle list SDG locomotives on sdg-bahn.de