DR series 99.77–79

Class 99.77–79
Numbering:	DR: 99 771-794 99 1771-1794 (from 1970) 099 736-757 (from 1992) MKWP : 12 and 13
Number:	26th
Manufacturer:	VEB Lokomotivbau Karl Marx
Year of construction (s):	1952-1956
Type :	1'E1 'h2t
Genre :	K 57.9
Gauge :	750 mm
Length over coupling:	11 300 mm
Length:	10,000 mm
Height:	3550 mm
Fixed wheelbase:	4000 mm
Total wheelbase:	7600 mm
Smallest bef. Radius:	50
Empty mass:	41.5 t
Service mass:	55.0 t
Friction mass:	45.0 t
Wheel set mass :	9.0 t
Top speed:	30 km / h
Indexed performance :	441 kW (600 hp)
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:	3200 mm
Grate area:	2.57 m²
Radiant heating surface:	8.50 m²
Tubular heating surface:	68.40 m²
Superheater area :	28.80 m²
Evaporation heating surface:	76.90 m²
Water supply:	5.8 m³
Fuel supply:	3.6 tons of coal
Locomotive brake:	Knorr compressed air brake (originally controlled by suction air) with additional brake
Train brake:	Hardy suction air brake , Körting suction air brake , Knorr compressed air brake
Train heating:	steam
Coupling type:	Scharfenberg coupling , on Rügen and at the Trusebahn compensating coupling

The vehicles of the 99.77-79 series are narrow-gauge tank locomotives of the Deutsche Reichsbahn for 750 mm gauge , which were built from 1952 to 1956, especially for the narrow-gauge railways in Saxony . They resemble in their parameters largely to the 1928 to 1933 built unit locomotives of the series 99.73-76 . Of the 26 locomotives built, 22 are still preserved today.

Together with the standard locomotives, these locomotives are often referred to as Saxon VII K as a continuation of the old Saxon generic names . This designation is not formally correct as it was no longer procured by the Saxon State Railways .

history

The narrow-gauge railways in the area of ​​what was later to become the GDR survived the Second World War without significant damage, only a few lines were dismantled as reparations . However, the Saxon narrow-gauge railways in particular lacked powerful machines. On the one hand, more than 20 locomotives of the series 99.51-60 , 99.61 and 99.64-71 were lost due to war missions, on the other hand, the SMAD had another 30 machines of the series 99.51-60, 99.64-71 and 99.73-76 confiscated as reparations for the USSR and after Transport east. The class 99.64–71 and 99.73–76 locomotives, some of which were not even 20 years old, represented an enormous loss, as they were the most modern of the 750 mm narrow-gauge railways.

Locomotive 99 772 as an exhibit at the Leipzig trade fair , 1952

The situation was made worse by the start of uranium mining in the Ore Mountains by Wismut AG , which significantly increased the transport services on the Cranzahl-Kurort Oberwiesenthal , Grünstädtel-Oberrittersgrün , Schönfeld-Wiesa-Meinersdorf and Wilischthal-Thum routes . But traffic also increased on the other narrow-gauge routes after the Second World War. In addition, there was the lack of hard coal , so that it had to be switched to lignite firing. This brought with it some disadvantages , as the existing locomotives were not designed for this.

In 1950, VEB Lokomotivbau Karl Marx was commissioned to develop a new locomotive. The design basis was the standard locomotives of the class 99.73-76 designed in the 1920s , which had proven themselves. The only differences are essentially the increased capacity of the coal box and the design of the frame. The external differences are limited to the now completely closed driver's cab and the missing Knorr surface preheater in front of the chimney.

From 1952 to 1957 a total of 24 locomotives were delivered to the Deutsche Reichsbahn. They were given the company numbers 99 771 to 99 794. The locomotives were located in the Thum , Wilsdruff and Meiningen ( Trusebahn ) depots. Two more locomotives were delivered to the VEB Mansfeld Kombinat "Wilhelm Pieck" (MKWP).

As early as the early 1980s, the repair and maintenance costs of the new locomotives rose sharply, due to the wear and tear of the undersized sheet metal frames and damage to the steam boiler. Initially, the long-term procurement of 30 Romanian diesel locomotives was planned, and the planned closure of the Zittau narrow-gauge railway as part of the expansion of lignite mining in the Lusatian lignite district would have freed up more standard locomotives that could have replaced the 99.77-79 series. Since the demand for machines continued to decline, including the re-gauging of the remnants of the Thumer network from Schönfeld-Wiesa to the Schönfeld paper mill in 1985, several particularly badly worn machines were shut down at the end of the 1980s.

A sticker identifies the locomotive 99 771 as the first locomotive built in the DR new build program, 2015

Such plans were stopped by the change in the GDR . The freight transport services declined sharply, but since the Zittau narrow-gauge railway continued to operate and the changes there made it no longer possible to buy diesel locomotives from Romanian production, the DR was threatened with a shortage of locomotives in the future. However, due to the decline in traffic, the responsible Reichsbahn repair works in Meiningen and Görlitz had sufficient opportunities for fundamental repairs to the machines. In addition to the boilers, the sheet metal frames should also be replaced. Basically, the renovation was tantamount to a new building. In 1990, the construction of the first new boilers began in Meiningen based on the construction plans for the two-part boilers from 1956, which were only changed in small details. Fundamental construction weaknesses such as the sheet metal frame were left unchanged during the general overhaul. First, the parked and other heavily worn machines were repaired for about seven million DM ; A total of 14 machines were equipped with new vessels and frames in 1991/92.

technical features

According to the then modern construction principles, the locomotives are completely welded constructions. Outwardly noticeable differences to the predecessor series 99.73-76 are the lack of a preheater with a piston feed pump and the high doors that completely close off the driver's cab.

boiler

The four domes on the boiler are clearly visible on 99 783, 2005

The long boiler of the 9.7 t heavy, steel- made steam locomotive boiler is welded from one shot (ie one piece). Only in the machines made in 1956 were two shots used. On the boiler with a 1400 mm diameter and 13 mm wall thickness, which is approved for 14  bar pressure , sits the feed dome behind the chimney , followed by a sand dome , then the steam dome and finally another sand dome.

Two suction steam jet pumps are available as a feed device. For the use of lignite, the grate area has been enlarged compared to the standard locomotive.

Frame and chassis

In contrast to the 99.73–76 series, a 30 mm thick sheet metal frame had to be used for the DR series 99.77–79 , as was already used in the class 52 war locomotives . The Lokomotivbau Karl Marx Babelsberg had lost the milling machine intended for processing the bar frames to the Soviet Union as a reparation payment and therefore no alternative in terms of design.

As with the standard locomotives, the third coupling axle is the driving axle and the running axles are guided in Bissel racks with ± 120 mm lateral displacement. The first, third and fifth coupling axles are firmly mounted in the frame, the second and fourth coupling axles can be shifted ± 24 mm laterally and the drive axle has no flange. This results in a fixed wheelbase of 4000 mm.

Others

The vehicles carry max. 5.8 m³ of water and 3.6 tons of coal with. The alternators are different. The machines on Rügen are equipped with standard turbo generators with a power of 0.5 kW. In Saxony, where all of the energy for the train is generated by the locomotive, significantly larger alternators with an output of 10 kW are used.

99 787 was equipped with a main oil firing system as a test vehicle in the 1990s. Although the machine proved itself in use, the oil furnace was dismantled after a few years because of the fuel costs.

commitment

Play media file

99 787 in Bertsdorf train station , 2015

The first operational areas were the routes Schönfeld-Wiesa-Thum-Meinersdorf and Wilischthal-Thum , the route Cranzahl-Kurort Oberwiesenthal (Fichtelbergbahn) and the route Freital-Hainsberg-Kurort Kipsdorf ( Weißeritztalbahn ). Some locomotives were also located in Thuringia near the Trusebahn .

After the closure of the Thumer network in the early 1970s, the locomotives were also used on the Lößnitzgrundbahn (Radebeul Ost – Radeburg). It was not until the 1980s that some locomotives came to the Rügen narrow-gauge railway and the Zittau network to remedy the local lack of locomotives.

Today, 15 locomotives belong to the Saxon Steam Railway Company (SDG) and - as far as they are operational - are in use on the Cranzahl – Oberwiesenthal, Freital-Hainsberg – Kipsdorf and Radebeul – Radeburg lines . Four locomotives belong to the Rügen bathing railway . A locomotive was sold to the Warthausen - Ochsenhausen ( Öchsle ) museum railway in Baden-Württemberg in 2001 and is now in service there. The Saxon-Upper Lusatian Railway Company (SOEG) has a locomotive, which is currently not operational. In Radebeul Ost station , the decommissioned locomotive 99 791 is parked in front of the train with the historic wagons of the Dresden Transport Museum .

Locomotive list

As of August 11, 2020

Company number	image	owner	Location	Remarks
99 771		SDG	Kipsdorf	switched off
99 772		SDG	Oberwiesenthal	operational
99 773		SDG	Oberwiesenthal	Intermediate examination
99 774		-	-	Retired in 1976 due to frame damage; last place of work: Thum
99 775		SDG	Radebeul East	Cultural monument of the city of Radebeul , parked
99 776		SDG	Oberwiesenthal	switched off
99 777		SDG	Kipsdorf	switched off
99 778		SDG	Nossen	Cultural monument of the city of Radebeul , not operational, permanent loan as a museum exhibit to IG Dampflok Nossen eV
99 779		SDG	Radebeul East	Cultural monument of the city of Radebeul , parked
99 780		SDG	Kipsdorf	switched off
99 781		RüBB	Putbus	switched off
99 782		RüBB	Putbus	operational
99 783		RüBB	Putbus	operational
99 784		RüBB	Putbus	operational
99 785		SDG	Oberwiesenthal	inoperable
99 786		SDG	Oberwiesenthal	parked in cran number
99 787		SOEG	Bertsdorf	switched off
99 788		Öchsle Bahn AG	Warthausen	operational
99 789		SDG	Radebeul East	switched off
99 790		SDG	Freital-Hainsberg	monument
99 791		TRR eV	Radebeul	Cultural monument of the city of Radebeul , inoperable exhibit at the narrow-gauge railway museum in Radebeul
99 792		-	-	Retired in 1972 in Thum, sold on May 31, 1973 to the “Panther” shoe factory in Ehrenfriedersdorf as a heating locomotive , dismantled in 1985
99 793		SDG	Freital-Hainsberg	Cultural monument of the city of Radebeul , operational
99 794		SDG	Oberwiesenthal	operational
12 "Patriot"		-	Mansfeld	scrapped
13 "pioneer"		-	Mansfeld	scrapped

literature

• 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 .
• Dirk Endisch: Class 99.77–79 . transpress Verlag, Stuttgart 2001, ISBN 3-613-71178-8 .

Web links

Commons : DR Class 99.77-79  - Collection of Pictures, Videos and Audio Files

• New construction locomotive of the DR on saechsische-schmalspurfahrzeuge.de ( Memento from September 2, 2013 in the web archive archive.today )

Individual evidence

1. ↑ Manfred Weisbrod, Wolfgang Petznick: Steam Locomotive Archive Volume 4: Series 97, 98 and 99. transpress-Verlag, Berlin 1981
2. ^ Vehicle lists from the companies mentioned
3. ↑ Vehicles in the Nossen depot ( memento of the original from September 23, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.