Early Development Steps of the Iconic Baureihe 52, or DRG Class 52
Steam locomotives were the logistical backbone of all military operations in the early 20th century. Certainly, the logistics of WW1 show this in great detail. Train tracks, wagons and locomotive counts exploded during these years. While Prussian P8s were the backbone of the ‘Länderbahnen’ in these years, the DRG Class 52, turned out to be the P8s counterpart in WW2. The BR 52 development is a topic that will take us on a tour through various articles in the following weeks.
A Brief Look at some Railway Developments in the 30s
The German Reich met ever-increasing logistical demands to support the front in the East during the Second World War. In December 1941 for instance, the frontline was 2400km east of the center of the Reich. Undoubtedly, this led to supply chain problems at home as well as at the front due to the failure of locomotive construction. Above all, bear in mind that the Reich only issued between 120 and 170 locomotives annually in the six years after 1933. Shockingly, this is not net of retired engines and less than 2% of the total stockpile. In further comparison, in 1924 some 90,000t, or 600 locomotives were delivered, compared to 50,000t and 120 locomotives in 1935.
Numbers picked up and reached 703 in 1939 and 945 in 1940. So why did the Reich neglect the railroad? After all, the Wehrmacht and High Command constantly neglected the Reichsbahn with their steel allocation plans up to 1941. In fact, it expected a fast victory and mostly based its supply line of their advance on aircraft and trucks. The total bombing of all railroad equipment in Poland in 1940 may have hinted at this already. That is to say, the OKW (Oberkommando der Wehrmacht) even rejected an increased steel allocation request by the Reichsbahn as late as December 1940.
This proved fatal in the winter of ’41 and consequently resulted in a shift of resources allocation and logistics management. The lack of locomotives, wagons and tracks culminated in the transport crisis of 1942. Closed factories due to coal shortage, lack of supplies and more were the result. Without a question, there will be a detailed article about this topic soon, but let’s get familiar with steam locomotives first, in order to understand war department requirements and shortcomings.
Steam Locomotive Engineering Basics
Without digging deeper, we can now move on to the development of medium load and weight locomotives. Because this is the field of operation the DRG Class BR 52 locomotives serviced. To clarify, Class 52 locomotives are freight and goods haulers with medium axle load, to be used on side tracks and lesser quality infrastructure. To demonstrate some of the essential thoughts behind locomotive designs, we need to look at some physics now.
Traction surface and wheel size
Freight locomotive designs focus on traction and a higher driving wheel count. To pull and push freight and personnel trains at mediocre speeds, five axles of medium diameter are better than three axles with massive diameter wheels. To clarify, more and smaller wheels increase the surface friction on the tracks and thereby the load capacity in tons. High-speed passenger steam locomotives, on the other hand, try to minimize friction.
The above graph shows this in an exaggerated and simplified way with hexagons. The total surface contact of the five hexagon wheels is larger than the three hexagon wheels. As such the lower train has more traction than the above one. Evidently, this is why the BR 52 locomotives have five driving axles and not 4 or 3.
Axle load and the distribution of weight
Additionally, more powered wheels lead to more weight distributed among them. More weight per axle increases the axle load, further increasing the force the locomotive can bring to the tracks. For this reason, a three-axle locomotive will have more weight spread to non driven axles and loses axle load. You can spot the driven axles by the red drive rod connecting them in my simple drawing.
Axle Load Explained with Wheel Size and Amount
Overall, the two graphs explain why most heavier goods locomotives have four or five wheels. Contrary to that, most passenger locomotives, like the DRG Class 01 have three driving axles with huge wheels of 2000mm diameter, in contrast to the 1400mm of the BR 52. It weighed 90t and had a friction mass of only 53t and a pulling force of 135kN compared to 75t and 214kN of a BR52. Its maximum speed of 130km/h surpassed the 80km/h of BR 52 by far, however.
BR 52 and 50 Developments
The same principles apply to Class 52 and its predecessor, Class 50. Hence both of them share an axle arrangement of 1’E. Development of the efficient goods hauling ‘Einheitslokomotive’ Class 50 took place between 1937 and 1939. The German Reich needed a standardized locomotive for branch and secondary lines to replace the hundreds of unique ‘Länderbahnen’ locomotives. Many were needed, but only a few allotted, as stated earlier.
The German Reich had around 20,000 locomotives in the 1920s, classified into 400 classes, with most classes having less than 10 locomotives. Repairing a Saxonian locomotive in Bavaria proved difficult to impossible, due to a lack of standardization of tools. Additionally, spare parts were only available at the manufacturer’s plant, if at all. This led to the development of the Einheitslokomotiven (standardized locomotives) in the 30s. Unquestionably the efforts were mainly based on the achievements of Richard F. P. Wagner, head of the ‘Reichsbahn Zentralamt’ (Reichsbahn Central office) from 1923 to 1942. His influence is notable to this day by locomotive classifications in Germany. The BR 50 and BR 52 development, amongst others, progressed swiftly owing to Wagner.
Refinement and the BR 50 ÜK
The manufacture of Class 50 locomotives still required a vast amount of special machinery. For the most part the ‘Reichsministerium für Bewaffnung und Munition’ (Reich Ministry of Armaments and War Production) or RMfBuM needed them for tank and airplane manufarturing in the early 40s. Consequently, this resulted in a refinement of Class 50 and many other ‘Einheitslokomotiven’. Firstly, a higher grade of standardization reduced the number of tools needed. Secondly, it freed up capacities and man-hours, as nonessential parts were omitted. Last but not least, vast amounts of forced labor filled the factories.
Übergangs Kriegslok – ÜK
A gradual implementation of these simplifications and modifications resulted in a vast amount of different Class 50 ÜK and early BR 52s. Actually, ÜK stands for ‘Übergangs Kriegslok’ (interim war locomotive) and is the transition lot between Class 50 and BR 52.
The Class 50 ÜK is a hermaphrodite between BR 50 and BR 52, sharing features with various degrees. This is a result of local stockpiles in the various factories which determined the composition of the first 328 interim locomotives. These locomotives had a mix of bar frames and any of the following could be present or not, like wind deflectors, spoked leading wheels, advanced frost protection compressor, and many more.
Bar and Plate Frame Development of the BR 52
Plate and bar frames are the basic design of the frame structure of all steam locomotives. The latter appeared fairly late at the turn of the 20th century thanks to advances in steel rolling technology. Ultimately, the warship armament industry was the main driver behind these changes. Let’s take a closer look at each of their features.
Bar frame design
Bar frames require more tooling and allow access to components for repairs. As such, the Class 50 and most modern locomotives in the 1920s to 1940s used the bar frame, if the machinery was available. Additionally, they are usually 100 to 120mm thick and have lots of gaps to save steel and weight. Moreover, bar frames are lower than plate frames, giving them more flexibility. Flexibility leads to smoother driving characteristics on uneven ballast works. However, lifting a bar frame without superstructure usually leads to a bending of the frame, as it could not support its own weight alone lengthwise. It was bolted or riveted together with its support structure.
Plate frame design
The plate frame on the other hand was thinner and could support its own weight but was susceptible to warping. As such, it always needed its interior support structure. Cheap and easier to manufacture plate frames are more rigid than bar frames but have lower shock absorption and running smoothness qualities. They are usually about 30mm thick and bolted, riveted as well as welded together. The increase in and technological advances in welding made plate frames more attractive again after the war. Therefore all Neubaulokomotiven (post-war locomotives in Germany) used plate frame designs, due to the superior welding possibilities.
BR 50 vs BR 52 – Basic Comparison
After we have established some basics about steam locomotive design, lets take a look into some BR 50 and BR 52 details. The table below summarizes some basic info about the two locomotives.
|Locomotive||52 001||50 001|
|Speed forwards / backwards||80 / 80km/h||80 / 80km/h|
|Length of locomotive||13,600mm||13,600mm|
|Length including tender||22,975mm||22,940mm|
|Empty / Duty weight locomotive||75.9 / 84.0t||78.6 / 86.9t|
|Locomotive and full tender weight||130t-139t||146.4t|
|Average coal usage per 1000km||19.5t||23.0t|
|Driving wheel diameter||1,400mm||1,400mm|
|Frame type||95% plate frame||Bar frame|
A reduction in weight of the BR 52 from 146t to 139t during the first months of development is rather significant. Further weight reductions later in the war, pushed the weight down to 130t while the total parts count remained at 5,000. The manhours saved amount to 40%. According to the Henschelstern, a propaganda paper run by Henschel & Sohn GmbH, the new production methods ‘saved 26t of materials and 6,000 man hours’. If you do the maths on the table below, 16t are apparent, the other 10t of savings are questionable.
BR 50 ÜK a Closer Look
Locomotives 52 002 to 349 were the so called Class 50 ÜK and manufactured by Henschel, Jung, Krauss-Maffei, BMAG (Schwarzkopff) and WLF. They mostly feature the Class 50 bar frame and some a modified kind of bar frame. However many of them show the development which leads to the DRG Class 52. They rolled off the plants from September 1942 till March 1943. By January and February 1942 however, Skoda, Schichau, MBA and Esslingen already rolled out Class 52s. Manufacturing of all three kinds, the Class 50s, 50 ÜK and BR 52s happened simultaneously for some time during the production shift, to use up the old stockpile.
There are reasons for the allocation of Class 50 ÜK allocations to the above-mentioned manufacturers. Businesses like Esslingen and MBA lacked the technology for bar frame manufacturing. As such, they were only able to produce the plate frame variants. The difference of allotted to delivered locomotives below is explained by two factors. Firstly, the constant bombing of factories and secondly by the requirements to produce tanks and artillery pieces. Manufacturing shifts hit Borsig and ‘Kanonenkönig’ (Canon king) Krupp the most. Krauss-Maffei later fell victim to the resources allocation cut of 20% in 1943 and shut down their locomotive factory.
Total Factory Output until the End of the War
|350 – 1099 Borsig LM||750||176|
|1100 – 1349 DWM Posen||250||369|
|1350 – 1599 Esslingen||250||283|
|1600 – 1849 Graffenstaden||250||139|
|1850 – 2089 Henschel (Kondens)||240||169|
|2090 – 3099 Henschel||1010||949|
|3100 – 3349 Jung||250||221|
|3350 – 4049 Krauss-Maffei||700||274|
|4050 – 4749 Krupp||700||0|
|4750 – 5124 MBA||375||472|
|3125 – 5374 Krenau||250||424|
|5375 – 5874 Schichau||500||529|
|5875 – 6624 BMAG||750||639|
|6625 – 6684 Skoda||60||60|
|6685 – 7434 WLF||750||1115|
|7435 – 7559 Warschau (Skoda)||125||93|
The 6,029 BR 52s include 150 locomotives for export.
- 100 CFR – Câile Ferate Române – Romanian National Railway
- 25 HDZ – Hrvatske Zeljeznice – Croatian Railways
- 15 SDZ -Serbian Railways
- 10 TCDD – State Railways of the Republic of Turkey
In addition to all this, we must add the 338 Class 50 ÜK and this equals a total war output of 6,359 locomotives. Griebl/Wenzel claim 6209 whicle Gottwald states 6161. Another 86 were manufactured post-war. All sources mention the abstract listing of locomotives and parts as well as propaganda influence as possible margins of error.
Further photos and interesting information may be found here. In conjunction with the BR 52, our article about the 2cm Flakvierling 38 on K4T30 is also an interesting further topic.
Have a good day and feel free to share your input. Alex
Sources and further reading
- Griebl / Wenzel – Geschichte der Deutschen Kriegslokomotiven 1971
- Gottwald – Deutsche Kriegslokomotiven 1939-1945 1973
- Gottwald – Räder müssen Rollen, 2nd Edition 1974
- Eisenbahnmagazin 2. Februar 1979
- Eisenbahnjournal Sonderausgabe II, 1996
- Dampflokomotive – Technik und Funktion, VGB Verlag, 2016
How many BR 52s were actually built?
338 BR50ÜK, 6029 BR52 before 1945 and another 89 post war are the numbers cited from most recent research. They differ slightly from Gottwald and other scholars and their publications form the 70s and 80s. The article covers all this in detail.
Where were the locomotives built?
There were a total of 16 manufacturers involved in the planned production, while only 15 actually produced them. That is, Krupp never made a single locomotive as the constant bombing of their facilities and their required focus on tank production led to WLF and others taking over their allotted slots.
What does BR 52 stand for?
BR is the baureihe, or class of the locomotive. German standardization of nomenclature separated locomotives into various categories. All BRs between 40 and 59 were goods hauling locomotives. 60-79 were passenger locomotives and 01-19 high speed locomotives, for example.