In the allocation of operating numbers up to 1970 the Deutsche Bundesbahn and the Deutsche Reichsbahn in East Germany took care for the most part, to ensure that they did not overlap with one another.
The locomotives were grouped together into classes of the same or similar design. Locomotives were given the range of numbers from 5000 - 7000. However the numbering was not consecutive, but was based on two technical aspects.
The first two figures gave the axle load in Mp. However in order to ensure numbers fell within the allocated range, the number 50 had to be added. So, for example, locomotives with an axle load of 10 Mp were given the serial number 60.
The last two figures were based on whether the locomotive used saturated or superheated steam. Saturated steam locomotives were given the numbers 01 to 75 and superheated locomotives the numbers 76 to 99.
For narrow gauge locomotives with the class number 99 a similar scheme was chosen. Here however, there were additional rules which were supposed to be followed when allocating the operating numbers (Betriebsnummer). Due to their complexity, these rules were not always adhered to. The first digit gave the rail gauge: 3 = 600 mm, 4 = 750 mm, 5 and 6 = 1,000 mm. The next digit indicated the axle load, with a '0' being used for 10 Mp and a '1' for 11 Mp. The last two digits indicated whether the engine was a tank locomotive (01 to 50) or a tender locomotive (from 51).
As part of the nationalisation of private railways on 1 January 1950, railbuses also had to be integrated into the numbering scheme. The spare numbers from 500 were used for this purpose. The railbuses were, however, given different class numbers (Stammnummern) from those in the DRG's system. Class 133 was allocated to light, rail-omnibus-like, two-axled vehicles without standard drawbars or buffers. All other twin-axled railbuses were given the class number 135. Petrol-driven vehicles were given serial numbers 501 to 503, diesel-motored ones numbers 509 to 550 and diesel-electric vehicles the numbers 551 to 553.
All four-, five- and six-axled railbuses were organised into Class 137. Those with diesel-mechanical drives were given serial numbers 511 to 532, diesel-electrics were number from 551 to 566 and diesel-hydraulic vehicles were given numbers from 571 onwards.
The electric railbuses that were taken over were designated as Class ET 188 and the steam railbuses acquired from the Oderbruchbahn were grouped into Class DT 151.
Modified railbuses used their previous DRG wagon numbers, but these were prefixed by the DR with the letters VT.
For new vehicles another scheme was used. In 1954 a new system was introduced for the fast Ganz (DR Class VT 12.14) railbuses imported from Hungary. After the class letters 'VT' the next two digits indicated the top speed divided by 10. The average axle load followed, separated by a full stop. After a second full stop, were the two digits of the vehicle's serial number.
Yet another system was used from 1956. With this one the first gropu of numbers gave the motor power divided by 100, the second group the top speed/10 and the third group the 2- or 3-digit serial number. Trailer coaches, driving coaches and centre coaches were designated with the letters VB, VS and VM. Examples are Classes VT 2.09 and VT 18.16.
So by 1970 the DR had three different classification systems.
For the steam locomotives the previous class numbers remained largely unchanged and were left as two-digit numbers. Because, however, the first figure had to be a 1 for diesel locomotives and a 2 for electric locomotives, those classes affected had to be renumbered.
The following classes were changed:
The serial number which followed the two-digit class number was generally four digits long and the first one was used to distinguish between the different locomotive types.
The following rules applied to the serial numbers of standard gauge locomotives (Classes 01 to 98):
The following rules applied to the serial numbers of narrow gauge locomotives (Class 99):
Only grate-fired narrow gauge locomotives were renumbered, but if a narrow gauge locomotive was to be converted to oil-firing in subsequent years it would be given a:
In case an oil-fired locomotive was rebuilt to grate-firing, the first number was to be changed as follows:
The class numbers for internal combustion engined locomotives generally comprised 3 digits with a leading 1. The subsequent numbers were borrowed from their previous class numbers.
The serial numbers for internal combustion engined locomotives were retained as far as possible or reduced to the required three digits by dropping the first figure.
The small locomotives (Kleinlokomotiven) were given the class number 100. The serial numbers of locomotives in power group I were given a leading 0; power group II were given leading figures ranging from 1 to 7. The remaining small locomotives and narrow gauge locomotives were given a leading 9. In 1973 the narrow gauge engines were reclassified to Class 199.
On subsequent rebuilding the designation of locomotives was changed. This led to new classes being formed or sometimes just to the first digit of the serial number being changed.
The class numbers for electric locomotives generally consisted of 3 digits with a 2 as the first number. The following digits were borrowed from their previous class numbers.
To distinguish between different types, a 0, 2 or 9 was used as the leading digit of the 3-digit serial number.
Railbus class numbers usually had 3 digits which started either with a 1 or a 2 depending on the type of traction.
For internal combustion engined railbuses, the following system was chosen:
Narrow-gauge and works railbuses were organised into Classes 187 and 188.
To distinguish between the different types of railbus the serial numbers had a 0, 1 or 2 in the first position. Saloon railbuses were given serial numbers from 251, centre wagons leading digits 3 to 5, driving cars 6 and 7 and trailers a number 8.
For electric railbuses the following leading digits were used:
To distinguish between types the serial numbers began with 0, 2 or 9. Power cars were given odd numbers and driving, centre and trailing cars, even numbers.
Horst J. Obermayer, Manfred Weisbrod: Dampflok-Report Band Nr. 2. Hermann Merker Verlag Fürstenfeldbruck 1995, ISBN 3-922404-72-3